JP6160221B2 - Vehicle steering control device and vehicle steering control method - Google Patents

Description

  The present invention relates to a vehicle steering control device and a vehicle that are assisted by an actuator such as a steering motor in accordance with a steering operation of the steering wheel in a state where the torque transmission path between the steering wheel and the steered wheel is mechanically connected. The present invention relates to a steering control method.

  Conventionally, in a state where the torque transmission path between the steering wheel (steering wheel) and the steered wheel is mechanically separated, the steered wheel is set to an actuator such as a steered motor at a target steered angle according to the operation of the steering wheel. There is a steering control device that steers through the wheel. Such a steering control device generally forms a system (SBW system) referred to as steer-by-wire (SBW: Steer By Wire, which may be described as “SBW” in the following description). For example, it is described in Patent Document 1.

  The SBW system described in Patent Document 1 does not include a sensor (such as a rotary encoder) that detects an actual turning angle of a steered wheel (in the following description, may be described as “actual turning angle”). The purpose is to calculate the turning angle of the steered wheels. For this reason, the sum of the absolute angle within the steering angle range of the steering wheel and the deviation between the absolute angle of the steered wheels detected over a plurality of periods and the steered angle range The difference from the initial value obtained by detecting the angle within a plurality of periods is obtained as an offset amount. Then, the sum of the steering absolute angle and the offset amount, which are detected over a plurality of cycles within the steering angle range of the steered wheels, is calculated as a relative steered wheel steer angle, and the steered wheels are steered. Calculate the corner.

JP 2011-005933 A

By the way, in the conventional SBW system including the technique described in Patent Document 1, the torque transmission path between the steering wheel and the steered wheel may be configured to include a universal joint. This is configured according to the layout of various components between the steering wheel and the steered wheels.
However, in the technique described in Patent Document 1, the relative turning angle of the steered wheels is determined without considering the change of the steering angle input by the steering wheel and transmitted by the universal joint in the torque transmission path. The turning angle of the steered wheels is calculated.

Therefore, in a state where the torque transmission path is mechanically connected, such as when an abnormality occurs in a part of the SBW system, it is possible to appropriately detect the correspondence relationship between the steering angle of the steering wheel and the turning angle of the steered wheels. A difficult situation occurs. As a result, it is difficult to appropriately control the actuator that outputs the assist torque for assisting the turning of the steered wheels in accordance with the steering operation of the driver in a state where the torque transmission paths are mechanically connected. There is a problem of becoming.
The present invention has been made paying attention to the above-described problems, and provides a vehicle steering control device and a vehicle steering control method capable of appropriately controlling an actuator that outputs assist torque. Let it be an issue.

In order to solve the above problems, the present invention provides a torque transmission path between a steering wheel and a steered wheel, an open state in which the torque transmission path is mechanically separated, and a connection state in which the torque transmission path is mechanically coupled. And a clutch that switches between, a steering-side universal joint that mechanically connects between the steering wheel and the clutch, and a steering-side universal joint that mechanically connects between the steered wheels and the clutch, switching the command value of the assist torque is the torque for assisting the steering of steered wheels from the actuator in response to a steering operation of a driver, a steering torque applied to the steering wheel, the output torque ratio, the clutch connected state It is calculated based on the input / output torque ratio calculated in the above state . Here, the input / output torque ratio is a ratio between the steering angle input to the universal joint and the output angle output from the universal joint based on the input steering angle. The actuator that outputs the assist torque is a turning actuator that turns the steered wheels.
Further, the steering side clutch angle, which is the rotation angle on the steering wheel side of the torque transmission path, is calculated based on the detected steering angle, which is the rotation angle transmitted to the clutch via the steering side universal joint. The turning actuator rotation angle that is the rotation angle of the steering actuator is detected, and the detected turning actuator rotation angle is converted to the turning-side reverse output angle that is the rotation angle transmitted to the clutch through the turning-side universal joint. Based on this, a steering side clutch angle that is a rotation angle on the steered wheel side of the torque transmission path is calculated, and a clutch angle deviation that is a deviation between the calculated steering side clutch angle and the calculated steering side clutch angle is calculated.

In addition, the input / output torque ratio is the output angular velocity based on the change amount of the steered wheel side output angle within the angular velocity calculation time that is a preset time and the steering angular velocity based on the change amount of the steering angle of the steering wheel within the angular velocity calculation time. Ratio of the steering angle input to the universal joint and the output angle output from the universal joint based on the input steering angle, and the calculated clutch angle deviation is added to the calculated steering clutch angle Calculation is performed based on the value input to the universal joint output angular velocity calculation model with the steering angle for turning angle calculation as the steering wheel side input angle . Here, the steered wheel side output angle is an angle obtained by outputting the steered wheel side input angle, which is an angle based on the steering angle input to the universal joint, to the steered wheel side via the universal joint. The output angular velocity is a model equation indicating the relationship between the steering angular velocity and the output angular velocity, and is based on a value obtained by inputting the steering angle of the steering wheel and the output angle on the steered wheel side to a preset universal joint output angular velocity calculation model. calculate.

According to the present invention, the torque fluctuation that occurs in the torque transmission path due to the inconstant velocity of the universal joint and fluctuates with the change of the steering angle is based on the input / output torque ratio that is the ratio of the steering angular speed and the output angular speed. Can be estimated.
For this reason, it is possible to calculate the command value of the assist torque based on the input / output torque ratio according to the torque fluctuation, and even if the torque fluctuation occurs in the torque transmission path, the driver's steering operation can be performed. On the other hand, the actuator can be appropriately controlled.

1 is a diagram illustrating a schematic configuration of a vehicle including a vehicle steering control device according to a first embodiment of the present invention. 1 is a block diagram illustrating a schematic configuration of a vehicle steering control device according to a first embodiment of the present invention. FIG. It is a figure which shows the steering structure of a SBW system. It is a block diagram which shows the structure of a command calculating part. It is a block diagram which shows the process in which a clutch angle deviation calculation part calculates a clutch angle deviation. It is a figure which shows a waveform map. It is a block diagram which shows the process in which a turning angle calculation part calculates the turning angle of a steered wheel. It is a block diagram which shows the structure of an EPS control block. It is a figure which shows an input-output torque ratio map. It is a figure which shows the relationship between the rotating shaft which a single universal joint has, and the rotational motion around a rotating shaft. It is a figure which shows the relationship between the axis | shaft of the input side in an universal joint, and the axis | shaft of an output side. It is a figure which shows the relationship between the axis | shaft of the input side in an universal joint, the axis | shaft of an output side, and a phase angle. It is a flowchart which shows the process performed before shipment of a vehicle. It is a flowchart which shows the process which calculates and memorize | stores a clutch angle deviation among the processes performed with respect to the vehicle after shipment. It is a flowchart which shows the process which calculates the steering angle of a steered wheel among the processes performed with respect to the vehicle after shipment, and the process which correct | amends the relationship between a steering angle and a steering motor rotation angle. It is a flowchart which shows the process which a torque ratio calculating part calculates an input-output torque ratio. It is a block diagram which shows the process in which a torque ratio calculating part calculates the output angular velocity in each universal joint, and the process which calculates an integrated speed ratio. It is a time chart which shows operation | movement of the vehicle using the steering control apparatus for vehicles of 1st embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
(Constitution)
FIG. 1 is a diagram illustrating a schematic configuration of a vehicle including a vehicle steering control device 1 according to the present embodiment. FIG. 2 is a block diagram showing a schematic configuration of the vehicle steering control device 1 of the present embodiment.
The vehicle provided with the vehicle steering control device 1 of the present embodiment is a vehicle to which the SBW system is applied.

  Here, in the SBW system, by driving and controlling an actuator (for example, a steering motor) in accordance with a steering operation of a steering wheel (steering wheel) by a driver of the vehicle, by performing control to steer the steered wheel, Change the direction of travel of the vehicle. For the drive control of the steering motor, the clutch that is interposed between the steering wheel and the steered wheel is switched to the open state, which is the normal state, and the torque transmission path between the steering wheel and the steered wheel is mechanically separated. Perform in the state.

For example, when an abnormality occurs in a part of the SBW system, such as a disconnection, the driver is connected to the steering wheel by switching the clutch in the released state to the engaged state and mechanically connecting the torque transmission path. Steering of the steered wheels is continued using the applied force. In addition to this, EPS (Electric Power Steering) control for outputting assist torque from the steered motor is performed in accordance with the operation state (steering amount, steering torque, steering speed, etc.) of the steering wheel by the driver. Note that, for example, the configuration of the vehicle includes a control changeover switch arranged in the passenger compartment, and the driver switches the control from the SBW system to the EPS control by operating the control changeover switch. It is good also as a structure which can be performed to.
As shown in FIGS. 1 and 2, the vehicle steering control device 1 according to the present embodiment includes a steered motor 2, a steered motor control unit 4, a clutch 6, a reaction force motor 8, and a reaction force motor. A control unit 10 is provided.

The steered motor 2 is an electric motor that is driven according to the steered motor drive current output by the steered motor control unit 4 and rotates according to the target steered angle described above to steer the steered wheels. A steering actuator is formed. The steered motor 2 outputs a steered torque for turning steered wheels by being driven according to the steered motor drive current. As the steering actuator, it is possible to use a power cylinder, a hydraulic circuit including a solenoid, or the like in addition to the electric motor.
The steered motor 2 has a rotatable steered motor output shaft 12.
A steered output gear 12 a formed using a pinion gear is provided on the tip side of the steered motor output shaft 12.
The steered output gear 12a meshes with a rack gear 18a provided between both ends of the rack shaft 18 inserted through the steering rack 14.

The steered motor 2 is provided with a steered motor angle sensor 16 and a steered motor torque sensor 2t.
The steered motor angle sensor 16 detects the steered motor rotational angle that is the rotational angle of the steered motor 2, and sends an information signal including the detected steered motor rotational angle via the steered motor control unit 4. Output to the reaction force motor control unit 10.
The steered motor torque sensor 2t detects a steered motor torque that is a torque generated by the steered motor 2 during driving. Then, the steered motor torque sensor 2t outputs an information signal including the detected steered motor torque to the reaction force motor control unit 10. In the following description, the steering motor torque may be described as “torque sensor value Vtm”. Further, the steering motor torque detected by the steering motor torque sensor 2t may be converted into steering torque.

In the present embodiment, the steering motor torque detected by the steering motor torque sensor 2t is converted into steering torque that is torque applied by the driver to the steering wheel 32. And the case where the information signal containing this converted steering torque is output to the reaction force motor control part 10 is demonstrated.
The steering rack 14 is formed in a cylindrical shape, and a rack shaft 18 that is displaced in the vehicle width direction according to the rotation of the steering motor output shaft 12, that is, the rotation of the steering output gear 12a is inserted therethrough.
In addition, two stopper portions 14 a that cover the outer diameter surface of the rack shaft 18 from the entire circumference are provided inside the steering rack 14. The two stopper portions 14a are respectively provided on the right side and the left side in the vehicle width direction of the steering output gear 12a inside the steering rack 14. In addition, in FIG. 1, illustration of the stopper part 14a provided in the vehicle width direction right side rather than the steering output gear 12a is abbreviate | omitted among the two stopper parts 14a.

Of the portion of the rack shaft 18 that is inserted into the steering rack 14 and disposed inside, the portions on the right and left sides in the vehicle width direction of the stopper portion 14a are opposed to each other in the axial direction of the stopper portion 14a and the rack shaft 18. An end abutting member 18b is provided. In FIG. 1, of the two end contact members 18b, illustration of the end contact member 18b provided on the right side in the vehicle width direction from the stopper portion 14a is omitted.
Both ends of the rack shaft 18 are connected to the steered wheels 24 via tie rods 20 and knuckle arms 22, respectively. A tire axial force sensor 26 is provided between the rack shaft 18 and the tie rod 20.
The tire axial force sensor 26 detects an axial force that acts in the axial direction (vehicle width direction) of the rack shaft 18, and this detected axial force (may be described as “tire axial force” in the following description). Is output to the reaction force motor control unit 10.

The steered wheels 24 are front wheels (left and right front wheels) of the vehicle. Change the direction of travel of the vehicle. In the present embodiment, a case where the steered wheels 24 are formed of left and right front wheels will be described. Accordingly, in FIG. 1, the steered wheel 24 formed with the left front wheel is denoted as steered wheel 24L, and the steered wheel 24 formed with the right front wheel is denoted as steered wheel 24R.
The steered motor control unit 4 inputs and outputs information signals through the reaction force motor control unit 10 and a communication line 28 such as a CAN (Controller Area Network).
The steered motor control unit 4 includes a steered position servo control unit 30 and a steered side previous process content storage unit MA.
The steered position servo control unit 30 calculates a steered motor drive current for driving the steered motor 2, and outputs the calculated steered motor drive current to the steered motor 2.

Here, the steering motor drive current controls the steering torque described above, calculates a target turning angle according to the operation of the steering wheel, and turns the steering motor 2 according to the calculated target turning angle. This is a current for driving control.
The calculation of the turning motor drive current is performed by calculating a turning motor current command output by the reaction force motor control unit 10 and a command value (hereinafter referred to as a turning motor actual current) energizing the turning motor 2. In the description, it may be described as “steering motor actual current command It”. Specifically, the steered motor current command is corrected using the steered motor actual current command It, and the steered motor drive current is calculated.

The steered position servo control unit 30 measures the steered motor actual current command It, and estimates the temperature Tt of the steered motor 2 based on the measured steered motor actual current command It. Then, an information signal including the estimated temperature Tt of the steered motor 2 is output to the reaction force motor control unit 10. This is to estimate overheating of the motors (the steered motor 2 and the reaction force motor 8) due to resistance heat generation due to current application.
The steered motor actual current command It is measured, for example, by incorporating a substrate temperature sensor (not shown) in the steered motor 2 and using the incorporated substrate temperature sensor.
Here, as a method of estimating the temperature Tt of the steered motor 2 based on the steered motor actual current command It, for example, in a large current range, the steered motor actual current command It is used using the measured actual current value. Ask for. Specifically, the measured actual current value is compared with the current threshold value stored in advance, and when the measured actual current value is larger than the current threshold value, the measured actual current value is converted into the steering motor. Adopted as actual current command It.

On the other hand, in the small current region, the actual motor current command It is estimated based on the rotational speed of the steered motor 2 using the motor NT characteristic that defines the relationship between the rotational speed of the steered motor 2 and the torque. Specifically, the actual current value measured is not adopted as the steering motor actual current command It, and the current value estimated based on the number of revolutions of the steering motor 2 using the motor NT characteristics is used as the actual steering motor actual value. Adopted as current command It.
Then, the temperature Tt of the steered motor 2 is estimated using the steered motor actual current command It adopted as described above.
In addition, the description regarding the steering side last process content storage part MA is mentioned later.
The clutch 6 is interposed between the steering wheel 32 and the steered wheel 24 operated by the driver, and is switched to an open state or an engaged state according to a clutch drive current output from the reaction force motor control unit 10. Note that the clutch 6 is in an open state in a normal state.

Here, when the state of the clutch 6 is switched to the released state, the torque transmission path between the steering wheel 32 and the steered wheel 24 is mechanically separated, and the steering operation of the steering wheel 32 is not transmitted to the steered wheel 24. And On the other hand, when the state of the clutch 6 is switched to the engaged state, the torque transmission path between the steering wheel 32 and the steered wheel 24 is mechanically coupled, and the steering operation of the steering wheel 32 is transmitted to the steered wheel 24. And
A steering angle sensor 34, a steering torque sensor 36, a reaction force motor 8, and a reaction force motor angle sensor 38 are disposed between the steering wheel 32 and the clutch 6.
The steering angle sensor 34 is provided, for example, in a steering column that rotatably supports the steering wheel 32.

The steering angle sensor 34 detects a current steering angle that is a current rotation angle (steering angle) of the steering wheel 32. Then, the steering angle sensor 34 outputs an information signal including the detected current steering angle of the steering wheel 32 to the reaction force motor control unit 10. In the following description, the current steering angle may be described as “current steering angle θH”.
Here, a vehicle in recent years is often equipped with a sensor that can detect the steering angle of the steering wheel 32 as a standard. For this reason, in this embodiment, the case where the sensor which can detect the steering angle of the steering wheel 32 which is an existing sensor in the vehicle is used as the steering angle sensor 34 will be described.
Similarly to the steering angle sensor 34, the steering torque sensor 36 is provided, for example, in a steering column that rotatably supports the steering wheel 32.

The steering torque sensor 36 detects a steering torque that is a torque applied by the driver to the steering wheel 32. Then, the steering torque sensor 36 outputs an information signal including the detected steering torque to the reaction force motor control unit 10. In the following description, the steering torque may be described as “torque sensor value Vts”.
The reaction force motor 8 and the reaction force motor angle sensor 38 will be described later.
The clutch 6 has a pair of clutch plates 40 that are separated from each other in the opened state and mesh with each other in the engaged state. In FIG. 1 and the following description, of the pair of clutch plates 40, the clutch plate 40 disposed on the steering wheel 32 side is referred to as “steering wheel side clutch plate 40a”, and the clutch plate disposed on the steered wheel 24 side. 40 is referred to as a “steered wheel side clutch plate 40b”.

The steering wheel side clutch plate 40 a is attached to a steering shaft 42 that rotates together with the steering wheel 32, and rotates together with the steering shaft 42.
The steered wheel side clutch plate 40 b is attached to one end of the pinion shaft 44 and rotates together with the pinion shaft 44.
The other end of the pinion shaft 44 is disposed in the pinion 46.
The pinion 46 incorporates a steering gear (not shown) that meshes with the rack gear 18a. In addition, the pinion 46 is provided with a pinion shaft torque sensor 46t.
The pinion shaft torque sensor 46 t detects pinion shaft torque that is torque applied to the pinion shaft 44. Then, the pinion shaft torque sensor 46 t outputs an information signal including the detected pinion shaft torque to the reaction force motor control unit 10. In the following description, the pinion shaft torque may be described as “torque sensor value Vtp”.

In the present embodiment, the pinion shaft torque detected by the pinion shaft torque sensor 46t is converted into steering torque that is torque applied by the driver to the steering wheel 32. And the case where the information signal containing this converted steering torque is output to the reaction force motor control part 10 is demonstrated.
The steering gear rotates together with the pinion shaft 44. That is, the steering gear rotates with the steered wheel side clutch plate 40 b via the pinion shaft 44.

  The reaction force motor 8 is an electric motor that is driven according to a reaction force motor drive current output from the reaction force motor control unit 10, and forms a reaction force actuator that can output a steering reaction force to the steering wheel 32. Note that. The steering reaction force is output by rotating the steering shaft 42 that rotates together with the steering wheel 32. Here, the steering reaction force output from the reaction force motor 8 to the steering wheel 32 is calculated according to the tire axial force acting on the steered wheels 24 and the steering state of the steering wheel 32. This calculation is performed in a state where the clutch 6 is switched to the released state and the torque transmission path between the steering wheel 32 and the steered wheel 24 is mechanically separated. Thereby, an appropriate steering reaction force is transmitted to the driver who steers the steering wheel 32. That is, the steering reaction force output from the reaction force motor 8 to the steering wheel 32 is a reaction force acting in the direction opposite to the operation direction in which the driver steers the steering wheel 32. As the reaction force actuator, in addition to the electric motor, a power cylinder, a hydraulic circuit including a solenoid, or the like can be used.

The reaction force motor angle sensor 38 is a sensor provided in the reaction force motor 8.
The reaction force motor angle sensor 38 detects the rotation angle of the reaction force motor 8 and includes an information signal including the detected rotation angle (may be described as “reaction force motor rotation angle” in the following description). Is output to the reaction force motor control unit 10.
The reaction force motor control unit 10 inputs and outputs information signals via the steering motor control unit 4 and the communication line 28. In addition, the reaction force motor control unit 10 receives input of information signals output from the vehicle speed sensor 50 and the engine controller 52 via the communication line 28.
In addition, the reaction force motor control unit 10 drives and controls the reaction force motor 8 based on information signals received via the communication line 28 and information signals received from various sensors.

The vehicle speed sensor 50 is, for example, a known vehicle speed sensor, detects the vehicle speed of the vehicle, and outputs an information signal including the detected vehicle speed to the reaction force motor control unit 10.
The engine controller 52 (engine ECU) outputs an information signal including the state of the engine (not shown) (engine drive or engine stop) to the reaction force motor control unit 10.
In addition, the reaction force motor control unit 10 includes a command calculation unit 54, a reaction force servo control unit 56, a clutch control unit 58, and a reaction force side previous process content storage unit MB.
The command calculation unit 54 inputs information signals output from the vehicle speed sensor 50, the steering angle sensor 34, the engine controller 52, the steering torque sensor 36, the reaction force motor angle sensor 38, the tire axial force sensor 26, and the turning motor angle sensor 16. Receive.
The detailed configuration of the command calculation unit 54 will be described later.

The reaction force servo control unit 56 outputs a reaction force motor drive current for driving the reaction force motor 8 to the reaction force motor 8.
Further, the reaction force servo control unit 56 may describe the value of the current (reaction force motor actual current) that is actually energized to the reaction force motor 8 (in the following description, “reaction force motor current value Ih”). Measure).
Here, the calculation of the reaction force motor drive current is performed based on a reaction force motor current command (described later) output from the command calculation unit 54 and a reaction force motor current value Ih. Specifically, the reaction force motor current command is corrected using the reaction force motor current value Ih, and the reaction force motor drive current is calculated.

Further, the reaction force servo control unit 56 estimates the temperature Th of the reaction force motor 8 based on the measured reaction force motor current value Ih. The estimation of the temperature Th of the reaction force motor 8 is performed in the same procedure as the estimation of the temperature Tt of the turning motor 2 performed by the turning position servo control unit 30, for example.
Based on a clutch current command (described later) output from the command calculation unit 54, the clutch control unit 58 calculates a current necessary for switching the released clutch 6 to the engaged state as a clutch drive current. Then, the calculated clutch drive current is output to the clutch 6.
In addition, the description regarding the reaction force side last process content storage part MB is mentioned later.

Next, a detailed steering structure will be described with reference to FIGS. 1 and 2 and FIG.
FIG. 3 is a diagram showing a steering structure of the SBW system.
The steering wheel 32 is connected to one end of the steering shaft 42.
The steering shaft 42 is rotatably held by the steering column 5.
The other end of the steering shaft 42 is connected to one end of the steering side intermediate shaft 9 via the universal joint 7.
The steering column 5 is provided with a reaction force motor 8 connected to the steering shaft 42.

The reaction force motor 8 applies a reaction torque corresponding to the road surface reaction force transmitted from the steered wheel side toward the steering wheel according to the steered angle to the steering shaft 42. Thereby, even when the clutch 6 is disengaged, the driver can grasp the road surface reaction force according to the steered state.
The other end of the steering side intermediate shaft 9 is connected to one end of the clutch input shaft 13 via the universal joint 11.
The other end of the clutch input shaft 13 is concentrically opposed to one end of the clutch output shaft 17 via the clutch 6, and the clutch 6 disconnects (engages and disconnects) the clutch input shaft 13 and the clutch output shaft 17. Do.

The other end of the clutch output shaft 17 is connected to one end of the steered side intermediate shaft 21 via the universal joint 19.
The other end of the steered side intermediate shaft 21 is connected to one end of a pinion shaft 25 via a universal joint 23, and the other end of the pinion shaft 25 is connected to a rack and pinion type steering gear 27. In addition, although illustration is abbreviate | omitted, the both ends of the rack used as the output side of the steering gear 27 are each connected with the end of a right-and-left tie rod, and the other end of a tie rod is connected with the wheel. As described above, the torque transmission path is connected by the plurality of universal joints (7, 11, 19, 23).

  Therefore, when the clutch 6 is engaged, when the steering wheel 32 is rotated, the pinion 46 and the pinion shaft 25 are rotated. Here, the pinion 46 and the pinion shaft 25 rotate via the steering shaft 42, the steering side intermediate shaft 9, the clutch input shaft 13, the clutch output shaft 17, and the steered side intermediate shaft 21. The rotational movement of the pinion shaft 25 is a rack advance / retreat movement by the steering gear 27, and the wheels are steered by pushing and pulling the tie rods according to the rack advance / retreat.

A reaction force motor 8 is connected to the steering shaft 42. When the reaction force motor 8 is driven in a state where the clutch 6 is disengaged, a reaction force torque is applied to the steering shaft 42. Therefore, the reaction force received from the road surface when the wheels are steered is detected or estimated, and the reaction force motor 8 is driven and controlled in accordance with the detected or estimated reaction force, so that the reaction force against the driver's steering operation is reduced. Power is granted.
Usually, the steering motor 31 is driven and controlled while the clutch 6 is disengaged, and the reaction force motor 8 is driven and controlled to execute steer-by-wire, thereby obtaining desired steering characteristics and turning behavior characteristics. Realized and good operation feeling. On the other hand, when an abnormality occurs in the system, the steer-by-wire is stopped and the clutch 6 is returned to the engaged state as fail-safe to ensure mechanical backup.

The steering column 5 is supported on the vehicle body through a tilt pivot 41 so as to be swingable. The layout is such that the center position of the universal joint 7 between the steering shaft 42 and the steering side intermediate shaft 9 is different from the center position of the tilt pivot 41 when viewed from the side of the vehicle body.
The steering side intermediate shaft 9 and the steered side intermediate shaft 21 are each configured to be extendable and contractable in the axial direction.
The clutch 6 is fixed to the dash panel 45 via the bracket 43.

  As described above, the universal joint 7 and the universal joint 11 form a steering-side universal joint that mechanically connects the steering wheel 32 and the clutch 6. The universal joint 19 and the universal joint 23 form a steered-side universal joint that mechanically connects the steered wheel 24 and the clutch 6. That is, the torque transmission path includes a steering-side universal joint that mechanically connects the steering wheel 32 and the clutch 6, and a steering-side universal joint that mechanically connects the steered wheel 24 and the clutch 6. .

(Detailed configuration of the command calculation unit 54)
Next, the detailed configuration of the command calculation unit 54 will be described with reference to FIGS. 1 to 3 and FIG.
FIG. 4 is a block diagram illustrating a configuration of the command calculation unit 54.
As shown in FIG. 4, the command calculation unit 54 includes a neutral position storage unit 60, a steered motor current command calculation unit 62, and a clutch state switching unit 64. In addition, the command calculation unit 54 includes a steering side clutch angle calculation unit 66, a steering side clutch angle calculation unit 68, a clutch angle deviation calculation unit 70, a clutch angle deviation storage unit 72, and a turning angle storage unit. 74, a turning angle calculation unit 76, and an EPS control block 78.

  For example, the neutral position storage unit 60 sets both the steering angle of the steering wheel 32 and the actual turning angle of the steered wheels 24 at the neutral position: 0 [°] in the adjustment process performed at the time of manufacture of the vehicle or before shipment of the vehicle. The relationship between the steering angle and the turning motor rotation angle in the adjusted state is stored. The relationship between the steering angle and the turning motor rotation angle in a state where both the steering angle of the steering wheel 32 and the actual turning angle of the steered wheel 24 are adjusted to the neutral position is as follows. Deviation (deviation angle [deg]). In the present embodiment, as an example, the relationship between the steering angle and the turning motor rotation angle in a state where both the steering angle of the steering wheel 32 and the actual turning angle of the steered wheels 24 are adjusted to the neutral position is changed with respect to the steering angle. The case where the deviation of the rudder motor rotation angle is set to 0 [°] will be described.

Further, the neutral position storage unit 60 corrects (overwrites) the relationship between the stored steering angle and the steered motor rotation angle in accordance with the steered angle of the steered wheel 24 calculated by the steered angle calculating unit 76. Process. For example, when the turning angle of the steered wheels 24 calculated by the turning angle calculation unit 76 is 10 [°] in the clockwise direction (the direction in which the vehicle turns to the right), this processing is performed by the turning motor for the steering angle. This is a process of correcting (overwriting) the rotation angle deviation counterclockwise to 10 [°].
The steered motor current command calculation unit 62 includes a relationship between the steering angle and the steered motor rotation angle stored in the neutral position storage unit 60, the current steering angle θH detected by the steering angle sensor 34, and the vehicle speed sensor 50. A steering motor current command is calculated based on the detected vehicle speed. Then, an information signal including the calculated turning motor current command is output to the turning position servo control unit 30.
The clutch state switching unit 64 receives an information signal including the state of the engine from the engine controller 52.

  The clutch state switching unit 64 determines that the ignition switch of the vehicle is on when the information signal including the engine state includes the engine drive state, and the clutch current for switching the clutch 6 to the open state. Generate directives. Then, an information signal including the generated clutch current command is output to the clutch angle deviation calculation unit 70, the clutch angle deviation storage unit 72, and the clutch control unit 58. The determination that the ignition switch of the vehicle is on is not limited to the case where the information signal including the engine state includes the engine driving state. In this case, when it is detected that the ignition switch has been operated by the driver or the like, it may be determined that the ignition switch of the vehicle is on even if the engine is stopped. The same applies to the following description. Further, even when the engine is stopped, the ignition switch of the vehicle is in the on state, for example, when the operation position of the ignition switch is ACC (accessory position).

The clutch state switching unit 64 determines that the ignition switch of the vehicle is off when the information signal including the state of the engine includes a state of engine stop, and a clutch current for switching the clutch 6 to the connected state. Generate directives. Then, the information signal including the generated clutch current command is sent to the steering side clutch angle calculation unit 66, the steering side clutch angle calculation unit 68, the clutch angle deviation calculation unit 70, the clutch angle deviation storage unit 72, and the clutch control unit. Output to 58.
The steering side clutch angle calculation unit 66 receives an input of an information signal including a clutch current command from the clutch state switching unit 64. In addition, the steering side clutch angle calculation unit 66 receives an information signal including the current steering angle of the steering wheel 32 from the steering angle sensor 34. Further, the steering side clutch angle calculation unit 66 receives an information signal including the torque sensor value Vts from the steering torque sensor 36.

Then, when the clutch 6 is switched to the connected state, the steering side clutch angle calculation unit 66 is based on the current steering angle θH detected by the steering angle sensor 34 and is the rotation angle on the steering wheel 32 side of the torque transmission path. Calculate the clutch angle. Further, an information signal including the calculated steering side clutch angle is output to the clutch angle deviation calculating unit 70.
Here, the steering side clutch angle calculation unit 66 of the present embodiment sets the current steering angle detected by the steering angle sensor 34 to the steering side output angle that is the rotation angle transmitted to the clutch 6 via the steering side universal joint. Based on this, the steering side clutch angle is calculated. The process in which the steering side clutch angle calculation unit 66 calculates the steering side clutch angle will be described later.

The steered side clutch angle calculation unit 68 receives an input of an information signal including a clutch current command from the clutch state switching unit 64. In addition to this, the turning side clutch angle calculation unit 68 receives an input of an information signal including the turning motor rotation angle from the turning motor angle sensor 16. Further, the steered side clutch angle calculation unit 68 receives an input of an information signal including the torque sensor value Vts from the steering torque sensor 36.
And if the steering side clutch angle calculation part 68 switches the clutch 6 to a connection state, based on the steering motor rotation angle which the steering motor angle sensor 16 detected, the rotation angle in the steered wheel 24 side of a torque transmission path | route. The steered side clutch angle is calculated. Further, an information signal including the calculated steered side clutch angle is output to the clutch angle deviation calculating unit 70. The process in which the steered side clutch angle calculating unit 68 calculates the steered side clutch angle will be described later.

Here, the steered side clutch angle calculating unit 68 of the present embodiment is the rotational angle at which the steered motor rotation angle detected by the steered motor angle sensor 16 is transmitted to the clutch 6 via the steered side universal joint. A steering side clutch angle is calculated based on a certain turning side reverse output angle. The process in which the steering side clutch angle calculation unit 66 calculates the steering side clutch angle will be described later.
The clutch angle deviation calculating unit 70 receives an input of an information signal including a clutch current command from the clutch state switching unit 64. In addition, the clutch angle deviation calculating unit 70 receives an input of an information signal including the steering side clutch angle from the steering side clutch angle calculating unit 66. Further, the clutch angle deviation calculating unit 70 receives an input of an information signal including the steered side clutch angle from the steered side clutch angle calculating unit 68.

Then, the clutch angle deviation calculating unit 70 calculates a clutch angle deviation which is a deviation between the steering side clutch angle and the steered side clutch angle, and sends an information signal including the calculated clutch angle deviation to the clutch angle deviation storage unit 72. And it outputs to the turning angle calculation part 76. A specific process in which the clutch angle deviation calculating unit 70 calculates the clutch angle deviation will be described later.
The clutch angle deviation storage unit 72 receives an input of an information signal including a clutch current command from the clutch state switching unit 64. In addition, the clutch angle deviation storage unit 72 receives an information signal including the clutch angle deviation from the clutch angle deviation calculation unit 70.
And the clutch angle deviation memory | storage part 72 memorize | stores the clutch angle deviation at the time of switching the clutch 6 to a connection state. In addition, when the stored clutch angle deviation is updated (overwritten), the clutch angle deviation storage unit 72 outputs an information signal including the updated content of the clutch angle deviation to the torque ratio map storage unit 84.

The turning angle storage unit 74 receives an input of an information signal including a clutch current command from the clutch state switching unit 64. In addition, the turning angle storage unit 74 receives an input of an information signal including the turning motor rotation angle from the turning motor angle sensor 16.
And the turning angle memory | storage part 74 memorize | stores the turning angle of the steered wheel 24 when an ignition switch will be in an OFF state.
The turning angle calculation unit 76 receives an input of an information signal including a clutch current command from the clutch state switching unit 64. In addition, the turning angle calculation unit 76 receives an input of an information signal including the clutch angle deviation from the clutch angle deviation calculation unit 70. Further, the turning angle calculation unit 76 receives an input of an information signal including the torque sensor value Vts from the steering torque sensor 36.

Then, when the ignition switch is turned on, the turning angle calculation unit 76 determines the turning angle based on the clutch angle deviation calculated by the clutch angle deviation calculation unit 70 and the universal joint change angle before switching the clutch 6 to the released state. The turning angle of the steering wheel 24 is calculated. Further, an information signal including the calculated turning angle of the steered wheels 24 is output to the steered position servo control unit 30.
Here, the universal joint change angle is an angle calculated using a model stored in advance by the turning angle calculation unit 76 on the torque transmission path based on the current steering angle detected by the steering angle sensor 34. . The processing in which the turning angle calculation unit 76 calculates the turning angle of the steered wheels 24 and the model stored in the turning angle calculation unit 76 will be described later.

Here, in the present embodiment, as an example, the structure of the turning angle calculation unit 76 is stored when the current steering angle detected by the steering angle sensor 34 does not change while the ignition switch is in the OFF state. The turning angle stored by the unit 74 is calculated as the turning angle of the steered wheels 24. The turning angle stored in the turning angle storage unit 74 is acquired from the turning angle storage unit 74 when the current steering angle detected by the steering angle sensor 34 does not change while the ignition switch is off. To do.
The EPS control block 78 receives an information signal including the current steering angle of the steering wheel 32 from the steering angle sensor 34. The EPS control block 78 receives an input of an information signal including the turning motor rotation angle from the turning motor angle sensor 16. In addition, the EPS control block 78 receives an information signal including the vehicle speed from the vehicle speed sensor 50. Further, the EPS control block 78 receives an input of an information signal including the torque sensor value Vtp from the pinion shaft torque sensor 46t.

When the EPS control block 78 performs the above-described EPS control, when the clutch 6 in the released state is switched to the connected state, the steering motor current command corresponding to the assist torque is based on each received information signal. Is calculated. Then, an information signal including the calculated turning motor current command is output to the turning position servo control unit 30.
Here, the calculation of the steering motor current command includes the current steering angle θH detected by the steering angle sensor 34, the turning motor rotation angle detected by the steering motor angle sensor 16, the vehicle speed detected by the vehicle speed sensor 50, and This is performed based on the torque sensor value Vtm detected by the turning motor torque sensor 2t.
The detailed configuration of the EPS control block 78 will be described later.

(Process in which the clutch angle deviation calculating unit 70 calculates the clutch angle deviation)
Hereinafter, a specific process in which the clutch angle deviation calculating unit 70 calculates the clutch angle deviation will be described with reference to FIGS. 1 to 4 and FIGS. 5 and 6.
FIG. 5 is a block diagram illustrating a process in which the clutch angle deviation calculation unit 70 calculates the clutch angle deviation.
In the process of calculating the clutch angle deviation, the steering side clutch angle calculation unit 66 calculates the steering side clutch angle θcl_in, and the steering side clutch angle calculation unit 68 calculates the steering side clutch angle θcl_out. Then, a value obtained by subtracting the steering clutch angle θcl_in from the steering clutch angle θcl_out is calculated as the clutch angle deviation dθCL (“dθCL = θcl_out−θcl_in” shown in FIG. 5).

Hereinafter, a process for calculating the steering side clutch angle θcl_in and a process for calculating the steering side clutch angle θcl_out will be specifically described.
The process in which the steering side clutch angle calculation unit 66 calculates the steering side clutch angle In the process in which the steering side clutch angle calculation unit 66 calculates the steering side clutch angle, first, the torque sensor value Vts received from the steering torque sensor 36. An information signal including Then, it is determined whether or not the torque sensor value Vts is within a preset steering-side clutch angle calculation torque threshold value range. Here, the steering-side clutch angle calculation torque threshold is set to a value that provides an appropriate torque for performing the process of calculating the steering-side clutch angle, and is stored in the steering-side clutch angle calculation unit 66. Therefore, if the torque sensor value Vts is within the range of the steering-side clutch angle calculation torque threshold, the steering torque applied by the driver to the steering wheel 32 is appropriate for performing processing for calculating the steering-side clutch angle. Torque.

When the torque sensor value Vts is determined to be within the range of the steering side clutch angle calculation torque threshold, the following processing is performed.
When the ignition switch is turned off, the current steering angle detected by the steering angle sensor 34 is input as the input angle tan θ _In of the universal joint 7 into the following equation (1), and the output angle θ _out of the universal joint 7 is calculated. . In addition, the following formula | equation (1) is a formula which shows a universal joint output angle calculation model which can be used as a model for calculating the output angle of each universal joint. The principle of establishing the universal joint output angle calculation model will be described later.
Here, the universal joint output angle calculation model is set in, for example, an adjustment process performed before shipment of the vehicle, and is stored in the steering clutch angle calculation unit 66 and the turning angle calculation unit 76.

Here, “α” shown in the above formula (1) is the universal joint (7, 11, 19) in a plan view on a preset plane (for example, a plane parallel to the vertical direction and the vehicle longitudinal direction). 23) is an angle formed by the input side axis and the output side axis.
Therefore, the universal joint output angle calculation model is a model formula indicating the relationship between the steered wheel side input angle and the steered wheel side output angle. Here, the steering wheel side input angle is an angle input from the steering wheel 32 side to the universal joint, and the steered wheel side output angle is an angle obtained by outputting the steering wheel side input angle to the steered wheel 24 side via the universal joint. It is.

That is, when calculating the output angle θ _out of the universal joint 7, “α” shown in the above equation (1) is the output of the universal joint 7 (steering shaft 42) and the output of the universal joint 7. This is the angle formed by the side shaft (steering side intermediate shaft 9). In the following description, the angle α formed by the steering shaft 42 and the steering side intermediate shaft 9 may be defined as the joint angle α of the universal joint 7 and may be described as “joint angle α ₁ ”.
Joint angle alpha _1, for example, the current steering angle .theta.H, using the waveform map generated in advance, is calculated in the adjustment process or the like performed before shipment of the vehicle, the steering-side clutch angle calculating section 66, calculates the steering clutch angle Stored in the unit 68 and the turning angle calculation unit 76. The calculation and storing of the joint angle alpha ₁ after shipment of the vehicle, for example, may be performed in the garages and the like.

Further, the calculation of the joint angle alpha ₁ is an actual turning angle of the current steering angle and the steered wheels 24 of the steering wheel 32, the corresponding state of being adjusted to an angle (e.g., the current steering angle and the actual turning angle to each other, Both are performed in the neutral position: adjusted to 0 [°].
Here, the waveform map is a map shown in FIG. 6, and is stored in the clutch angle deviation calculation unit 70, for example. FIG. 6 is a diagram showing a waveform map, which is a map defined by mathematical formulas and the like regardless of the specifications of the vehicle.
In FIG. 6, the horizontal axis represents the steering angle (denoted as “steering angle [deg]” in the figure), and the vertical axis represents the deviation between the angle of the pinion 46 (pinion angle) and the steering angle (see FIG. In the above, it is described as “deviation angle [deg]”).

Here, since each universal joint has inconstant velocity, the relationship between the steering angle and the pinion angle is constant except for the state where the steering angle is 0 [deg], for example, as shown in FIG. The relationship between the pinion angle and the steering angle changes depending on the steering angle.
When calculating the joint angle α1, for example, the steering angle of the steering wheel 32 is changed to change the deviation angle [deg] in the waveform map. In this case, by changing the steering angle detecting upper and lower limit values of the deviation angle [deg], based on these detected upper and lower limits, and it calculates the joint angle alpha _1.
In addition, “θ _offset ” shown in the above formula (1) indicates the twist angle of the output-side shaft with respect to the input-side shaft of each universal joint (7, 11, 19, 23) in the torque transmission path. The phase angle.

That is, when calculating the phase angle θ _offset of the universal joint 7, “θ _offset ” shown in the above equation (1) is a phase angle indicating the twist angle of the steering-side intermediate shaft 9 with respect to the steering shaft 42. . In the following description, the phase angle indicating the twist angle of the steering-side intermediate shaft 9 with respect to the steering shaft 42 is defined as the phase angle θ _offset of the universal joint 7 and may be described as “phase angle θ _offset1 ”.
Since the phase angle θ _offset is a design item of the vehicle, for example, when the vehicle is manufactured, the phase angle θ _offset is stored in the steering side clutch angle calculation unit 66, the steering side clutch angle calculation unit 68, and the steering angle calculation unit 76. Note that the phase angle θ _offset may be detected and stored, for example, before shipment of the vehicle. Further, the detection and storage of the phase angle θ _offset may be performed, for example, at a maintenance shop after the vehicle is shipped.

When detecting the phase angle θ _offset , the current steering angle of the steering wheel 32 and the actual turning angle of the steered wheels 24 are adjusted to mutually corresponding angles (for example, the current steering angle and the actual turning angle). The angles are both adjusted to the neutral position: 0 [°].
Next, the output angle θ _out of the universal joint 7 calculated as described above is input to the above equation (1) as the input angle tan θ _In of the universal joint 11, and the output angle θ _out of the universal joint 11 is calculated. Then, the output angle θ _out of the universal joint 11 is calculated as the steering side clutch angle θcl_in.

Here, when calculating the output angle θ _out of the universal joint 11, “α” shown in the above equation (1) is the same as the input-side shaft (steering-side intermediate shaft 9) of the universal joint 11 and the universal joint. 11 is an angle formed by the output side shaft (clutch input shaft 13). In the following description, the angle α formed by the steering-side intermediate shaft 9 and the clutch input shaft 13 may be defined as the joint angle α of the universal joint 11 and described as “joint angle α ₂ ”.
When calculating the output angle θ _out of the universal joint 11, “θ _offset ” shown in the above equation (1) is the phase angle indicating the twist angle of the clutch input shaft 13 with respect to the steering side intermediate shaft 9. Become. In the following description, the phase angle indicating the twist angle of the clutch input shaft 13 with respect to the steering side intermediate shaft 9 is defined as the phase angle θ _offset of the universal joint 11 and may be described as “phase angle θ _offset2 ”. .

As described above, the steering side clutch angle calculation unit 66 inputs the current steering angle detected by the steering angle sensor 34 to a preset steering side universal joint output angle calculation model, and calculates the steering side clutch angle θcl_in.
Here, the steering-side universal joint output angle calculation model is the following two model formulas (E1, E2).
E1. A model equation E2. _{Where the} joint angle α ₁ is input as “α” and the phase angle θ _offset1 is input as “θ _offset ” in the above equation (1). The above formula (1), "alpha" and enter the joint angle alpha ₂ as "theta _offset" as inputs the phase angle theta _offset2 model equation

The process in which the steered side clutch angle calculating unit 68 calculates the steered side clutch angle In the process in which the steered side clutch angle calculating unit 68 calculates the steered side clutch angle, first, an input from the steering torque sensor 36 is received. The information signal including the torque sensor value Vts is referred to. Then, it is determined whether or not the torque sensor value Vts is within a preset turning threshold clutch angle calculation torque threshold. Here, the steering-side clutch angle calculation torque threshold is set to a value that provides an appropriate torque for performing the process of calculating the steering-side clutch angle, and is stored in the steering-side clutch angle calculation unit 68. Therefore, if the torque sensor value Vts is within the range of the steering-side clutch angle calculation torque threshold, the steering torque applied by the driver to the steering wheel 32 performs processing for calculating the steering-side clutch angle. Appropriate torque.

And if it determines with the torque sensor value Vts being within the range of the torque threshold value for steering side clutch angle calculation, the following processes will be performed.
The turning motor rotation angle at the time when the ignition switch is turned off is input to the following equation (2) as the reverse input angle tan θ _In of the universal joint 23, and the reverse output angle θ _out of the universal joint 23 is calculated. In addition, the following formula | equation (2) is a formula which shows a universal joint reverse output angle calculation model which can be used as a model for calculating the reverse output angle of each universal joint.
Here, the universal joint reverse output angle calculation model is set, for example, in an adjustment process performed before shipment of the vehicle, and is stored in the steered side clutch angle calculation unit 68.

Here, when calculating the reverse output angle θ _out of the universal joint 23, “α” shown in the above equation (2) is the axis on the input side of the universal joint 23 (the steered side intermediate shaft 21). This is the angle formed by the output side axis (pinion shaft 25) of the universal joint 23. In the following description, the angle α formed by the steered-side intermediate shaft 21 and the pinion shaft 25 may be defined as the joint angle α of the universal joint 23 and may be described as “joint angle α ₄ ”.
Therefore, the universal joint reverse output angle calculation model is a model formula indicating the relationship between the steered wheel side reverse input angle and the steered wheel side reverse output angle. Here, the steered wheel side reverse input angle is an angle input from the steered wheel 24 side to the steered side universal joint, and the steered wheel side reverse output angle is the steered wheel side reverse input angle via the steered side universal joint. Is output to the steering wheel 32 side.

Further, when calculating the reverse output angle θ _out of the universal joint 23, “θ _offset ” shown in the above equation (2) is a phase angle indicating a twist angle of the pinion shaft 25 with respect to the steered side intermediate shaft 21. It becomes. In the following description, the phase angle indicating the torsion angle of the pinion shaft 25 with respect to the steered side intermediate shaft 21 is defined as the phase angle θ _offset of the universal joint 23 and may be described as “phase angle θ _offset4 ”. .
Next, the reverse output angle θ _out of the universal joint 23 calculated as described above is input as the reverse input angle tan θ _In of the universal joint 19 to the above equation (2), and the reverse output angle θ _out of the universal joint 19 is calculate. Then, the reverse output angle θ _out of the universal joint 19 is calculated as the steered side clutch angle θcl_out.

Here, when calculating the reverse output angle θ _out of the universal joint 19, “α” shown in the above equation (2) is the axis on the input side of the universal joint 19 and the axis on the output side of the universal joint 19. Is the angle formed by Here, the input side axis of the universal joint 19 is the clutch output shaft 17, and the output side axis of the universal joint 19 is the steered side intermediate shaft 21. In the following description, the angle α formed by the clutch output shaft 17 and the steered side intermediate shaft 21 may be defined as the joint angle α of the universal joint 19 and may be described as “joint angle α ₃ ”.
When calculating the reverse output angle θ _out of the universal joint 19, “θ _offset ” shown in the above equation (2) is a phase indicating the twist angle of the steered intermediate shaft 21 with respect to the clutch output shaft 17. It becomes a corner. In the following description, the phase angle indicating the twist angle of the steered-side intermediate shaft 21 relative to the clutch output shaft 17 is defined as the phase angle θ _offset of the universal joint 19 and may be described as “phase angle θ _offset3 ”. is there.

As described above, the turning side clutch angle calculation unit 68 inputs the turning motor rotation angle detected by the turning motor angle sensor 16 to the preset universal joint reverse output angle calculation model, and turns the turning side clutch angle θcl_out. Is calculated.
In the above description, the processing is performed using the equations (1) and (2), but the present invention is not limited to this. That is, for example, the processing may be performed using a map indicating the relationship between the current steering angle and the steering clutch angle θcl_in and a map indicating the relationship between the turning motor rotation angle and the steering clutch angle θcl_out.

(Process in which the turning angle calculation unit 76 calculates the turning angle of the steered wheels 24)
Hereinafter, a specific process in which the turning angle calculation unit 76 calculates the turning angle of the steered wheels 24 will be described with reference to FIGS. 1 to 6 and FIG. 7.
FIG. 7 is a block diagram illustrating a process in which the turning angle calculation unit 76 calculates the turning angle of the steered wheels 24.
In the process of calculating the turning angle of the steered wheels 24, first, an information signal including the torque sensor value Vts received from the steering torque sensor 36 is referred to. Then, it is determined whether or not the torque sensor value Vts is within a preset turning angle calculation torque threshold. Here, the turning angle calculation torque threshold is set to a value that provides an appropriate torque for performing the process of calculating the turning angle, and is stored in the turning angle calculation unit 76. Therefore, if the torque sensor value Vts is within the range of the turning angle calculation torque threshold, the steering torque applied by the driver to the steering wheel 32 is an appropriate torque for performing the process of calculating the turning angle. is there.

When it is determined that the torque sensor value Vts is within the range of the turning angle calculation torque threshold, the following processing is performed.
The current steering angle detected by the steering angle sensor 34 at the time when the ignition switch is turned on is input as the input angle tan θ _In of the universal joint 7 to the above equation (1). Thereby, the output angle θ _out of the universal joint 7 is calculated.
Next, the output angle θ _out of the universal joint 7 calculated as described above is input to the above equation (1) as the input angle tan θ _In of the universal joint 11, and the output angle θ _out of the universal joint 11 is calculated. Then, the output angle θ _out of the universal joint 11 is calculated as the steering side clutch angle θcl_in.

Here, in the process of calculating the turning angle of the steered wheels 24, the steering-side clutch angle θcl_in calculated as described above is added to the clutch angle deviation dθCL stored in the clutch angle deviation storage unit 72. As a result, the turning angle calculation turning-side clutch angle Pθcl_out is calculated (“Pθcl_out = θcl_in + dθCL” shown in FIG. 7). That is, the turning angle calculation unit 76 acquires information on the clutch angle deviation dθCL stored from the clutch angle deviation storage unit 72 when calculating the turning angle of the steered wheels 24.
Then, the turning angle calculation turning side clutch angle Pθcl_out calculated as described above is input to the above equation (1) as the input angle tan θ _In of the universal joint 19, and the output angle θ _out of the universal joint 19 is calculated. To do.
Next, the output angle θ _out of the universal joint 19 calculated as described above is input to the above equation (1) as the input angle tan θ _In of the universal joint 23, and the output angle θ _out of the universal joint 23 is calculated.

After calculating the output angle theta _out of the universal joint 23, the output angle theta _out of the universal joint 23 which is the calculated, subtracting the offset component of each universal joint (7,11,19,23). Thereby, the influence by the offset component of each universal joint (7, 11, 19, 23) is removed from the output angle θ _out of the universal joint 23, and the turning angle of the steered wheels 24 is calculated.
Here, the offset component of each universal joint (7, 11, 19, 23) is expressed by the following equation (3). In addition, the following formula | equation (3) is a formula which shows a universal joint offset component calculation model which can be used as a model for calculating the offset component of each universal joint. The principle of establishing the universal joint offset component calculation model will be described later.
Here, the universal joint offset component calculation model is set, for example, in an adjustment process performed before shipment of the vehicle, and is stored in the turning angle calculation unit 76.

Therefore, the universal joint offset component calculation model is a model formula indicating a phase angle indicating a twist angle of the output shaft with respect to the input shaft of each universal joint (7, 11, 19, 23).
In addition to this, in the process of calculating the turning angle of the steered wheels 24, the output angle θ _out of the universal joint 23 obtained by dividing the offset component of each universal joint (7, 11, 19, 23) is used as the torque sensor value described above. Correction is performed based on Vtp.
Here, to correct the output angle θ _out of the universal joint 23, the torsion angles of the shafts and the universal joints (7, 11, 19, 23) based on the torque sensor value Vtp are used. The shafts are the steering shaft 42, the steering side intermediate shaft 9, the clutch output shaft 17, the steered side intermediate shaft 21, and the pinion shaft 25.

Moreover, the torsion angle of each shaft and each universal joint is represented by the following formula (4). The following equation (4) is a torque sensor model that can be used as a model for correcting the twist angle of each shaft and each universal joint when calculating the steered angle of the steered wheels 24. It is a formula which shows.
Torsion angle = torque sensor value Vtp [Nm] / torsional rigidity [Nm / rad] of each shaft and each universal joint (4)
Therefore, the torque sensor model is a model showing the relationship between the steering torque based on the pinion shaft torque detected by the pinion shaft torque sensor 46t, the torsional rigidity of each universal joint, and the torsional rigidity of the input shaft and output shaft of each universal joint. It becomes an expression.

Here, the torque sensor model is set, for example, in an adjustment process performed before the vehicle is shipped, and is stored in the turning angle calculation unit 76.
In the present embodiment, as an example, when the output angle θ _out of the universal joint 23 is corrected using the twist angle of each shaft and each universal joint, the twist angle is added to the output angle θ _out of the universal joint 23. The case where it does is demonstrated.
Thus, the turning angle calculation unit 76 calculates the turning angle of the steered wheels 24 based on the change angle at which the turning angle calculation turning-side clutch angle Pθcl_out has changed via the turning-side universal joint.
In addition, the turning angle calculation unit 76 of the present embodiment is configured based on a value obtained by inputting the turning angle calculation turning-side clutch angle Pθcl_out to a turning-side universal joint output angle calculation model set in advance. Calculate the turning angle.

Here, the turning-side universal joint output angle calculation model is the following two model formulas (E3, E4).
E3. The above formula (1), enter the joint angle alpha ₃ as "alpha", "theta _offset" as model inputs the phase angle theta _OFFSET3 expression E4. The above formula (1), enter the joint angle alpha ₄ as "alpha", "theta _offset" model equation thus entered a phase angle theta _OFFSET4 as a steering-side universal joint output angle calculation model, steered side Universal The joint output angle calculation model is a model formula based on the universal joint output angle calculation model shown by the above formula (1).

Further, the turning angle calculation unit 76 of the present embodiment subtracts the offset component of each universal joint from the change angle at which the turning angle calculation turning-side clutch angle Pθcl_out has changed via the turning-side universal joint. Based on this, the turning angle of the steered wheels 24 is calculated.
In addition, the turning angle calculation unit 76 of the present embodiment calculates the change angle at which the turning angle calculation turning-side clutch angle Pθcl_out has changed via the turning-side universal joint using the torque sensor model. Correct using the twist angle of the path. And based on this corrected value, the turning angle of the steered wheels 24 is calculated.

(Detailed configuration of EPS control block 78)
The detailed configuration of the EPS control block 78 will be described below with reference to FIGS. 1 to 7 and FIGS. 8 and 9. FIG.
As shown in FIG. 8, the EPS control block 78 includes a torque ratio calculation unit 80, a torque ratio map generation unit 82, a torque ratio map storage unit 84, and an assist torque calculation unit 86. FIG. 8 is a block diagram showing the configuration of the EPS control block 78.
The torque ratio calculation unit 80 receives input of an information signal including a current steering angle of the steering wheel 32, an information signal including a turning motor rotation angle, and an information signal including a torque sensor value Vtp.

Then, the torque ratio calculation unit 80, based on each input information signal, the ratio between the steering angle input to the torque transmission path and the output angle output from the torque transmission path based on the input steering angle. The input / output torque ratio which is a parameter based on Then, an information signal including the calculated input / output torque ratio is output to the torque ratio map generation unit 82 and the assist torque calculation unit 86. The process in which the torque ratio calculation unit 80 calculates the input / output torque ratio will be described later.
The torque ratio map generator 82 receives an information signal including the current steering angle of the steering wheel 32. In addition, the torque ratio map generator 82 receives an information signal including an input / output torque ratio from the torque ratio calculator 80.

Then, the torque ratio map generation unit 82 generates an input / output torque ratio map indicating the relationship between the current steering angle input to the torque transmission path and the input / output torque ratio corresponding to the current steering angle.
Specifically, the input / output torque ratio corresponding to the current steering angle while the current steering angle changes from 0 [°] to 180 [°], that is, while the current steering angle changes with a change width of 180 degrees. Is detected. Then, the fluctuation of the input / output torque ratio while the current steering angle changes from 0 [°] to 180 [°] is calculated, and the calculated fluctuation of the input / output torque ratio is made to correspond to the current steering angle. An output torque ratio map is generated.
Here, in the input / output torque ratio map, as shown in FIG. 9, the horizontal axis indicates the current steering angle (indicated as “steering angle” in the figure), and the vertical axis indicates the input / output torque ratio (in the figure). Then, it is described as “torque ratio”). FIG. 9 is a diagram showing an input / output torque ratio map.

Further, as shown in FIG. 9, the input / output torque ratio map is a map in which the input / output torque ratio changes in one cycle while the current steering angle changes from 0 [°] to 180 [°]. . That is, the input / output torque ratio with respect to the current steering angle varies for one cycle while the current steering angle changes from 0 [°] to 180 [°].
Further, the input / output torque ratio map is generated by, for example, processing performed before shipment of the vehicle or processing performed after shipment of the vehicle.
The torque ratio map storage unit 84 receives an input of an information signal including an input / output torque ratio map from the torque ratio map generation unit 82. In addition, the torque ratio map storage unit 84 receives an input of an information signal including the updated content of the clutch angle deviation from the clutch angle deviation storage unit 72.

Then, for example, in the state where the input / output torque ratio map is not stored, such as during an adjustment process performed before shipment of the vehicle, the input / output torque ratio map is based on the information signal received from the torque ratio map generator 82. Remember.
Further, when the torque ratio map storage unit 84 receives an input of an information signal including the updated content of the clutch angle deviation, the torque ratio map storage unit 84 stores the input / output stored based on the information signal received from the torque ratio map generation unit 82. Update the torque ratio map.
That is, when the clutch angle deviation dθCL calculated by the clutch angle deviation calculation unit 70 changes, the torque ratio map storage unit 84 converts the stored torque ratio map into an input / output torque ratio map corresponding to the changed clutch angle deviation dθCL. Change to

The assist torque calculation unit 86 receives input of an information signal including the current steering angle of the steering wheel 32, an information signal including the turning motor rotation angle, an information signal including the torque sensor value Vtp, and an information signal including the vehicle speed. . In addition, the assist torque calculator 86 receives an information signal including an input / output torque ratio from the torque ratio calculator 80. Furthermore, the assist torque calculation unit 86 acquires information including the stored input / output torque ratio map from the torque ratio map storage unit 84.
Then, the assist torque calculation unit 86 calculates an assist torque command value based on each input information signal and the input / output torque ratio map stored in the torque ratio map storage unit 84. Then, an information signal including the calculated assist torque command value (shown as “assist torque command value” in the figure) is output to the steered motor control unit 4.

Here, the assist torque is a torque for assisting (assisting) the turning of the steered wheels 24 by the steered motor 2 in accordance with the steering operation of the steering wheel 32 by the driver during the EPS control.
Further, when calculating the command value of the assist torque, the input / output torque ratio included in the information signal received from the torque ratio calculation unit 80 and the input / output torque ratio map stored in the torque ratio map storage unit 84 are stored. At least one of them is used.
That is, the assist torque calculation unit 86 outputs at least one of the torque sensor value Vtp, the input / output torque ratio calculated by the torque ratio calculation unit 80, and the input / output torque ratio map stored in the torque ratio map storage unit 84. Based on this, a command value for assist torque is calculated.
Further, the assist torque calculation unit 86 of the present embodiment corrects the torque sensor value Vtp with the input / output torque ratio calculated by the torque ratio calculation unit 80, and calculates an assist torque command value.

(Principle for establishing universal joint output angle calculation model)
Hereinafter, the principle that the universal joint output angle calculation model is established will be described with reference to FIGS. 1 to 9 and FIGS. 10 to 12. FIG.
FIG. 10 is a diagram illustrating the relationship between the rotation axis of a single universal joint and the rotational motion around the rotation axis. In addition, in FIG. 10, the steering wheel 32 is typically shown for description. That is, the single universal joint shown in FIG.
As shown in FIG. 10, the universal joint has three rotation axes (x axis, y axis, z axis), and the rotation matrix R around each rotation axis is expressed by the following equation (5) ) To (7). Expression (5) is an expression indicating a rotation matrix R (x, θ) around the x axis, and Expression (6) is an expression indicating a rotation matrix R (y, θ) around the y axis. Expression (7) is an expression indicating a rotation matrix R (z, θ) around the z axis.

  The rotation matrices R (x, θ), R (y, θ), and R (z, θ) around the rotation axes shown in the above equations (5) to (7) are expressed by the following equations (8). As shown in FIG. 2, it is possible to convert the rotation matrix R into one.

Further, as shown in FIG. 11, the rotation of the input side shaft is replaced with the symbol “φ” from θ ₀ shown in FIG. 10, and the inclination angle of the output side shaft with respect to the z axis is represented by the symbol “θ _z The rotation angle of the shaft on the output side (which may be described as “output angle” in the following description) is defined by the symbol “Ψ”. Thereby, the definition of the attitude angle in a universal joint is shown by the following formulas (9) to (11). FIG. 11 is a diagram illustrating the relationship between the input side shaft and the output side shaft in the universal joint. In FIG. 11, for the sake of explanation, the flow of force from the input side shaft to the output side shaft is indicated by straight arrows.

Here, when the constraint conditions shown by the following equations (12) and (13) are added to the above equations (9) to (11), the relationship between the input angle tanθ ₀ to the universal joint and the output angle ψ is It is shown by the following formula (14).

In the above equation (14), when the output angle Ψ is replaced with the universal joint output angle θ _out and the input angle tan θ ₀ is replaced with the universal joint input angle tan θ _In , the following equation (15) is established.

Here, the above equation (15) is an equation indicating the relationship between the universal joint input angle tan θ _In and the output angle θ _out in a state where the universal joint phase angle θ _offset does not exist.
In addition, as the configuration of the vehicle, it is rare that the input shaft and the output shaft of each universal joint are arranged in series according to the layout of various components between the steering wheel 32 and the steered wheels 24. For this reason, a configuration in which the phase angle θ _offset of the universal joint exists is common.

That is, as shown in FIG. 12, in a vehicle having a general configuration, there is a phase angle θ _offset between the input angle tan θ _In and the output angle θ _out of the universal joint. FIG. 12 is a diagram illustrating the relationship between the phase angle and the input-side axis and the output-side axis in the universal joint. In FIG. 12, for the sake of explanation, the flow of force from the input side shaft to the output side shaft is indicated by straight arrows.
Therefore, when the phase angle θ _offset is added to the input angle tan θ _In with respect to the relationship between the input angle tan θ _In and the output angle θ _out of the universal joint shown in the above formula (15), the above formula (1) The universal joint output angle calculation model shown is established.

(Principle for establishing universal joint offset component calculation model)
Hereinafter, the principle that the universal joint offset component calculation model is established will be described with reference to FIGS.
When calculating the turning angle of the steered wheels 24, as described above, the output angle theta _out of the universal joint 23, to eliminate the influence of offset component of each universal joint. Therefore, in the above equation (15), when the input angle tan θ _In and the output angle θ _out of the universal joint are 0 [°], the offset component of each universal joint is subtracted by subtracting the offset component from the following equation (16). Remove the effects of ingredients.

Therefore, when the offset component of the universal joint is subtracted from the relationship between the input angle tan θ _In and the output angle θ _out of the universal joint represented by the above equation (15), the universal joint offset component represented by the above equation (3) is obtained. A calculation model is established.

(Steering side previous processing content storage unit MA, reaction force side previous processing content storage unit MB)
Hereinafter, with reference to FIGS. 1 to 12, the configuration of the steered side previous process content storage unit MA and the configuration of the reaction force side previous process content storage unit MB will be described.
The steered side previous processing content storage unit MA is formed using, for example, an EEPROM (Electrically Erasable Programmable Read-Only Memory).
Further, the steered side previous processing content storage unit MA receives an input of an information signal including the state of the engine from the engine controller 52, and further receives an information signal including the current steering angle of the steering wheel 32 from the steering angle sensor 34. Receive input. In addition to this, the steered-side previous processing content storage unit MA receives an input of an information signal including the clutch angle deviation from the clutch angle deviation calculation unit 70, and further turns the steered wheels 24 from the turning angle calculation unit 76. Receives information signal including steering angle.

Then, the steered side previous processing content storage unit MA stores the current steering angle, the clutch angle deviation, and the steered angle of the steered wheels 24 at the time when the ignition switch is turned off.
The reaction force side previous process content storage unit MB is formed by using, for example, an EEPROM, like the steered side previous process content storage unit MA.
The reaction force side previous processing content storage unit MB is similar to the steering side previous processing content storage unit MA from the engine controller 52, the steering angle sensor 34, the clutch angle deviation calculation unit 70, and the turning angle calculation unit 76, respectively. , Receive information signal input.
Then, the reaction force side previous process content storage unit MB, like the steered side previous process content storage unit MA, the current steering angle, the clutch angle deviation, and the steered wheels 24 at the time when the ignition switch is turned off. The turning angle is memorized.

(Processing performed by the command calculation unit 54)
Next, processing performed by the command calculation unit 54 will be described with reference to FIGS. 1 to 12 and FIGS. 13 to 15.
The processing performed by the command calculation unit 54 includes, for example, processing performed before shipment of the vehicle and processing performed on the vehicle after shipment.

Processing Performed Before Shipment of Vehicle FIG. 13 is a flowchart showing processing performed before shipment of the vehicle.
The processing performed by the command calculation unit 54 before the vehicle is shipped includes processing for calculating and storing the joint angle α and processing for storing the phase angle θ _offset .
As shown in FIG. 13, when the process to be performed before the vehicle is shipped (START), first, the process of step S10 is performed.
In step S10, for example, in a maintenance shop or the like, both the steering angle of the steering wheel 32 and the actual turning angle of the steered wheels 24 are adjusted to the neutral position (the “steering angle and actual turning angle shown in the figure are set to the neutral position”). adjust. When the steering angle and the actual turning angle are adjusted to the neutral position in step S10, the process performed by the command calculation unit 54 before the vehicle is shipped moves to step S20.

In step S20, the joint angles α _{1 to} α ₄ are calculated and stored in the steering side clutch angle calculating unit 66, the steered side clutch angle calculating unit 68, and the steered angle calculating unit 76 (see “Joint angle α shown in the figure”). Calculate / store ”). When the joint angle α is calculated and stored in step S20, the process performed by the command calculation unit 54 before the vehicle is shipped moves to step S30.
In step S30, the phase angles θ _{offset1 to} θ _offset4 are _stored in the steering side clutch angle calculation unit 66, the turning side clutch angle calculation unit 68, and the turning angle calculation unit 76 (“phase angle θ _offset shown in the figure is stored”). )). When the phase angle θ _offset is stored in step S30, the process performed by the command calculation unit 54 before the vehicle is shipped moves to step S40.
In step S40, the deviation of the steering motor rotation angle with respect to the steering angle is stored in the neutral position storage unit 60 as the relationship between the steering angle and the steering motor rotation angle ("neutral position storage" shown in the figure). When the relationship between the steering angle and the turning motor rotation angle is stored in step S40, the process performed by the command calculation unit 54 before the vehicle is shipped is ended (END).

Processing performed on the vehicle after shipment The processing performed by the command calculation unit 54 on the vehicle after shipment includes processing for calculating and storing the clutch angle deviation and processing for calculating the turning angle of the steered wheels 24. There is a process of correcting the relationship between the steering angle and the turning motor rotation angle.
FIG. 14 is a flowchart showing a process for calculating and storing the clutch angle deviation among the processes performed on the vehicle after shipment. Note that the command calculation unit 54 performs processing described below at a preset period (for example, 5 [ms]).
As shown in FIG. 14, when the process of calculating the clutch angle deviation is started (START), first, the process of step S100 is performed.

In step S100, a process ("IGN-OFF?" Shown in the drawing) for determining whether or not the ignition switch is in an OFF state is performed.
If it is determined in step S100 that the ignition switch is in the OFF state (“Yes” shown in the drawing), the process of calculating the clutch angle deviation moves to step S110.
On the other hand, when it is determined in step S100 that the ignition switch is not in the OFF state (“No” shown in the figure), the process of calculating the clutch angle deviation repeats the process of step S100.

In step S110, the clutch state switching unit 64 outputs a clutch current command for switching the clutch 6 to the engaged state to the clutch 6. In addition to this, referring to the clutch drive current output to the clutch 6, it is determined whether or not the clutch 6 is in the engaged state (completely engaged state not including the slip engaged state) ("clutch engagement shown in the figure"?")I do.
If it is determined in step S110 that the clutch 6 is in the engaged state (“Yes” shown in the drawing), the process of calculating the clutch angle deviation proceeds to step S120.
On the other hand, if it is determined in step S110 that the clutch 6 is not engaged ("No" shown in the figure), the process of calculating the clutch angle deviation repeats the process of step S110.

In step S120, it is determined whether or not the torque sensor value Vts is within the range of the steering-side clutch angle calculation torque threshold ("Vts is within the range of the steering-side clutch angle calculation torque threshold" shown in the figure). )I do.
If it is determined in step S120 that the torque sensor value Vts is within the range of the steering-side clutch angle calculation torque threshold ("Yes" shown in the figure), the process of calculating the clutch angle deviation proceeds to step S130. .
On the other hand, if it is determined in step S120 that the torque sensor value Vts is outside the range of the steering clutch angle calculation torque threshold ("No" shown in the figure), the process of calculating the clutch angle deviation is performed in step S120. Repeat the process.

In step S130, the steering clutch angle calculator 66 calculates the steering clutch angle θcl_in (“calculates the steering clutch angle θcl_in” shown in the drawing) using the universal joint output angle calculation model. When the steering side clutch angle θcl_in is calculated in step S130, the process of calculating the clutch angle deviation proceeds to step S140.
In step S140, a process for determining whether or not the torque sensor value Vts is within the range of the steering-side clutch angle calculation torque threshold ("Vts is within the range of the steering-side clutch angle calculation torque threshold shown in the figure"). ?")I do.
If it is determined in step S140 that the torque sensor value Vts is within the range of the steering-side clutch angle calculation torque threshold ("Yes" shown in the figure), the process of calculating the clutch angle deviation proceeds to step S150. To do.

On the other hand, if it is determined in step S140 that the torque sensor value Vts is outside the range of the steering clutch angle calculation torque threshold ("No" in the figure), the process of calculating the clutch angle deviation is performed in step S140. Repeat the process.
In step S150, the steering-side clutch angle calculation unit 68 calculates the steering-side clutch angle θcl_out using the universal joint reverse output angle calculation model (“calculates the steering-side clutch angle θcl_out” shown in the figure). Process. When the steered side clutch angle θcl_out is calculated in step S150, the process of calculating the clutch angle deviation proceeds to step S160.

In step S160, the steering side clutch angle θcl_in calculated in step S130 is subtracted from the steered side clutch angle θcl_out calculated in step S150. Thereby, in step S160, the clutch angle deviation calculating unit 70 performs a process of calculating the clutch angle deviation dθCL (“calculate the clutch angle deviation dθCL” shown in the drawing). When the clutch angle deviation dθCL is calculated in step S160, the process for calculating the clutch angle deviation proceeds to step S170.
In step S170, the clutch angle deviation storage unit 72 stores the clutch angle deviation dθCL calculated in step S160 (“stores clutch angle deviation dθCL” shown in the figure). When the clutch angle deviation dθCL is stored in step S170, the process of calculating the clutch angle deviation is ended (END).

Processing for calculating the turning angle of the steered wheels 24 and processing for correcting the relationship between the steering angle and the turning motor rotation angle FIG. It is a flowchart which shows the process which calculates the process which calculates a steering angle, and the relationship between a steering angle and a steering motor rotation angle.
The flowchart shown in FIG. 15 starts (START) when the ignition switch changes from the off state to the on state, and first, the process of step S200 is performed.
In step S200, a process of determining whether or not the torque sensor value Vts is within the range of the turning angle calculation torque threshold (“Vts is within the range of the turning angle calculation torque threshold?” Shown in the figure). Do.

If it is determined in step S200 that the torque sensor value Vts is within the range of the turning angle calculation torque threshold ("Yes" shown in the figure), the process of calculating the turning angle of the steered wheels 24 is step S210. Migrate to
On the other hand, when it is determined in step S200 that the torque sensor value Vts is outside the range of the turning angle calculation torque threshold ("No" shown in the figure), the process of calculating the turning angle of the steered wheels 24 is as follows. The process of step S200 is repeated.

In step S210, the current steering angle when the ignition switch is turned on is input to the universal joint output angle calculation model, and the output angle θ _out of the universal joint 11 is calculated as the steering clutch angle θcl_in. Thereby, in step S210, the process of calculating the output angle of the steering-side universal joint (“calculating the output angle of the steering-side universal joint” shown in the figure) is performed. When the output angle of the steering-side universal joint is calculated in step S210, the process of calculating the turning angle of the steered wheels 24 proceeds to step S220.

  In step S220, the clutch angle deviation dθCL stored in step S170 is added to the steering clutch angle θcl_in, which is the output angle of the steering universal joint calculated in step S210. As a result, in step S220, a steering angle calculation-use turning side clutch angle Pθcl_out is calculated (“calculate the turning angle calculation-use turning-side clutch angle Pθcl_out” shown in the drawing). In step S220, when the turning angle calculation-use turning side clutch angle Pθcl_out is calculated, the processing for calculating the turning angle of the steered wheels 24 proceeds to step S230.

In step S230, the turning angle calculation turning-side clutch angle Pθcl_out calculated in step S220 is input to the universal joint output angle calculation model, and the output angle θ _out of the universal joint 23 is calculated. Thereby, in step S230, the process which calculates the output angle of a steering side universal joint ("calculate the output angle of a steering side universal joint" shown in a figure) is performed. When the output angle of the steered universal joint is calculated in step S230, the process of calculating the steered angle of the steered wheels 24 proceeds to step S240.

In step S240, the output angle theta _out of the universal joint 23 calculated in step S230, the performs processing of subtracting an offset component based on the universal joint offset component calculation model (shown in FIG. "Subtracting the offset component"). Thereby, in step S240, the influence by the offset component of each universal joint (7, 11, 19, 23) is removed from the output angle θ _out of the universal joint 23. When the offset component is subtracted from the output angle θ _out of the universal joint 23 in step S240, the process of calculating the turning angle of the steered wheels 24 proceeds to step S250.

In step S250, a process of correcting the output angle θ _out of the universal joint 23 obtained by subtracting the offset component in step S240 using a torque sensor model (“corrected by the torque sensor model” shown in the figure) is performed. When the output angle θ _out of the universal joint 23 is corrected by the torque sensor model in step S250, the process of calculating the turning angle of the steered wheels 24 proceeds to step S260. Then, the process shifts from the process of calculating the steered angle of the steered wheels 24 to the process of correcting the relationship between the steering angle and the steered motor rotation angle.

In step S260, the relationship between the current steering angle used in step S210 and the output angle θ _out corrected in step S250, and the steering angle and the turning motor rotation angle stored in the neutral position storage unit 60 in step S40 described above. Browse relationships. Then, current and deviation a is shipped after the deviation between the output angle theta _out corrected by the steering angle and the step S250 that used in step S210, whether the pre-shipment deviation which is a deviation stored in the neutral position storage unit 60 are different Processing for determination (“deviation after shipment ≠ deviation before shipment?” Shown in the figure) is performed.

If it is determined in step S260 that the post-shipment deviation and the pre-shipment deviation are different (“Yes” shown in the figure), the process of correcting the relationship between the steering angle and the turning motor rotation angle proceeds to step S270.
On the other hand, if it is determined in step S260 that the post-shipment deviation and the pre-shipment deviation are equal (“No” shown in the figure), the process of correcting the relationship between the steering angle and the turning motor rotation angle proceeds to step S280. To do.
In step S270, the relationship between the steering angle and the turning motor rotation angle stored in the neutral position storage unit 60 in step S40 is corrected to the relationship based on the post-shipment deviation corrected in step S250 ("Neutral position shown in the figure"). Correction ”) is performed. In step S270, when the relationship between the steering angle stored in the neutral position storage unit 60 and the turning motor rotation angle is corrected, the processing for correcting the relationship between the steering angle and the turning motor rotation angle proceeds to step S290.

In step S280, a process of maintaining the relationship between the steering angle and the turning motor rotation angle stored in the neutral position storage unit 60 in step S40 without correcting ("maintain neutral position" shown in the figure) is performed. In step S280, if the relationship between the steering angle stored in the neutral position storage unit 60 and the turning motor rotation angle is maintained, the process of correcting the relationship between the steering angle and the turning motor rotation angle proceeds to step S290.
In step S290, the clutch state switching unit 64 outputs a clutch current command for switching the clutch 6 to the released state to the clutch 6 ("output clutch release command" shown in the figure). In step S290, when a clutch current command for switching the clutch 6 to the disengaged state is output to the clutch 6, the process of correcting the relationship between the steering angle and the turning motor rotation angle ends (END).

(Process in which the torque ratio calculation unit 80 calculates the input / output torque ratio)
Hereinafter, with reference to FIGS. 1 to 15, a process in which the torque ratio calculation unit 80 calculates the input / output torque ratio among the processes performed by the EPS control block 78 will be described using FIG. 16.
FIG. 16 is a flowchart showing a process in which the torque ratio calculation unit 80 calculates the input / output torque ratio.
When the flowchart shown in FIG. 16 is started (START), first, as a process of step S300, the process of setting the clutch 6 to the engaged state ("clutch engagement" shown in the figure) while maintaining the ignition switch in the on state is performed. Do. In step S300, the clutch 6 is processed to be in a completely engaged state that does not include the slip engaged state. In step S300, when the clutch 6 is in the engaged state, the processing for calculating the input / output torque ratio proceeds to step S310.

In step S310, a process of determining whether or not the clutch angle deviation stored in the clutch angle deviation storage unit 72 has been updated to the latest clutch angle deviation dθCL (“Clutch angle deviation updated?” Shown in the figure). )I do.
If it is determined in step S310 that the clutch angle deviation dθCL has not been updated (“No” shown in the figure), the processing for calculating the input / output torque ratio proceeds to step S320.
On the other hand, if it is determined in step S310 that the clutch angle deviation dθCL has been updated (“Yes” shown in the figure), the processing for calculating the input / output torque ratio proceeds to step S340.

  In step S320, the clutch angle deviation calculator 70 calculates the clutch angle deviation dθCL ("clutch angle deviation calculation" shown in the figure). When the clutch angle deviation dθCL is calculated in step S320, the process of calculating the input / output torque ratio proceeds to step S330. The process for calculating the clutch angle deviation dθCL is, for example, the above-described steps S120 to S120 except that the current steering angle and the turning motor rotation angle when the ignition switch is turned on and the clutch 6 is engaged are used. A process similar to S160 is used.

In step S330, the clutch angle deviation stored in the clutch angle deviation storage unit 72 is updated to the clutch angle deviation dθCL calculated in step S320 ("clutch angle deviation update" shown in the drawing). When the clutch angle deviation dθCL is updated in step S330, the process of calculating the input / output torque ratio proceeds to step S310. In addition, as a process which updates clutch angle deviation d (theta) CL, the process similar to step S170 mentioned above is used, for example.
In step S340, the steering angle sensor 34 detects the current steering angle θH when the clutch 6 is engaged (“current steering angle detection” shown in the figure). When the current steering angle θH is detected in step S340, the processing for calculating the input / output torque ratio proceeds to step S350.

  In step S350, the steered angle calculation unit 76 calculates the steered angle of the steered wheels 24 when the clutch 6 is engaged as the current estimated value of the pinion angle ("present pinion angle estimation" shown in the figure). ) Is performed. When the current estimated value of the pinion angle is calculated in step S350, the processing for calculating the input / output torque ratio proceeds to step S360. In the following description, the current estimated value of the pinion angle calculated in step S350 may be indicated as “current pinion angle f (θH)”. Moreover, as a process which calculates the present estimated value of a pinion angle, the process similar to step S200-S250 mentioned above is used.

  In step S360, a preset angular velocity calculation time Δt (for example, 100 [ms]) and a virtual displacement angle ΔθH are input to the following equation (17). Thereby, in step S360, a process of calculating a steering angular velocity based on the amount of change in the steering angle within the angular velocity calculation time Δt ("steering angular velocity calculation" shown in the figure) is performed. When the steering angular velocity is calculated in step S360, the process for calculating the input / output torque ratio proceeds to step S370. In the following description, the steering angular velocity calculated in step S360 may be indicated as “ωθH”. That is, the steering angular velocity ωθH is a velocity based on the amount of change in the angular velocity calculation time Δt of the angle input from the steering wheel 32 side to each universal joint (7, 11, 19, 23).

Here, the angular velocity calculation time Δt is, for example, a value that corresponds to the steering wheel operation by the driver of the vehicle and the amount of change in the angle input to each universal joint from the steering wheel 32 side is about several [deg]. Set.
The virtual displacement angle ΔθH is a parameter corresponding to the amount of change in the steering angle within the angular velocity calculation time Δt.

In step S370, the steering angular velocity ωθH calculated in step S360 is input to the following equation (18), and the output angular velocity at each universal joint (7, 11, 19, 23) is calculated (“output angular velocity calculation shown in the figure”). )) Is performed. When the output angular velocity is calculated in step S370, the processing for calculating the input / output torque ratio proceeds to step S380. In the following description, the output angular velocity calculated in step S370 may be indicated as “ωθP”. In addition, description of processing for calculating the output angular velocity ωθP in each universal joint (7, 11, 19, 23) will be described later.
In addition, the following formula | equation (18) is a formula which shows a universal joint output angular velocity calculation model which can be used as a model for calculating the output angular velocity of each universal joint.

Here, the output angular velocity ωθP is input to each universal joint (7, 11, 19, 23), and is output to the steered wheel 24 side via each universal joint (7, 11, 19, 23). This is a speed based on the amount of change within the angular velocity calculation time Δt.
Therefore, the universal joint output angular velocity calculation model is a model formula showing the relationship between the steering angular velocity ωθH and the output angular velocity ωθP.
In step S380, using the steering angular velocity ωθH and the output angular velocities ωθP used in step S370, the speed ratios in the universal joints (7, 11, 19, 23) are integrated ("integrate each speed ratio" shown in the figure). ) Is performed. In step S380, when the speed ratios at the universal joints are integrated, the processing for calculating the input / output torque ratio proceeds to step S390. In the following description, the speed ratio integrated in step S380 may be indicated as “integrated speed ratio ωθP _int / ωθH”.

In step S390, calculates the reciprocal of the integrated speed ratio ωθP _int / ωθH calculated in step S380, converts the integrated speed ratio ωθP _int / ωθH the output torque ratio ( "converted into output torque ratio" shown in FIG. ) Is performed. That is, in step S390, the input / output torque ratio T _ratio is calculated by the following equation (19). When the input / output torque ratio T _ratio is calculated in step S390, the processing for calculating the input / output torque ratio ends (END).
T _ratio = 1 / (ωθP _int / ωθH) (19)

Here, the speed ratio between the steering angular velocity ωθH and the output angular velocity ωθP is the reciprocal of the input / output torque ratio T _ratio . Therefore, it is possible to estimate the torque amplification factor in the torque transmission path using the input / output torque ratio T _ratio calculated based on the integrated speed ratio ωθP _int / ωθH.
As described above, the torque ratio calculation unit 80 calculates the input / output torque ratio T _ratio based on the value of the turning angle calculation turning-side clutch angle Pθcl_out input to the universal joint output angle calculation model.
Further, the assist torque calculation unit 86 calculates an assist torque command value based on the input / output torque ratio T _ratio calculated by the torque ratio calculation unit 80 with the clutch 6 switched to the connected state.

(Process for calculating output angular velocity ωθP at each universal joint, process for calculating integrated speed ratio ωθP _int / ωθH)
Hereinafter, with reference to FIG. 1 to FIG. 16, the output angular velocity at each of the universal joints (7, 11, 19, 23) in the processing in which the torque ratio calculation unit 80 calculates the input / output torque ratio using FIG. 17. A process for calculating ωθP will be described. Further, a process for calculating the integrated speed ratio ωθP _int / ωθH will be described.
FIG. 17 is a block diagram illustrating a process in which the torque ratio calculation unit 80 calculates the output angular velocity ωθP in each universal joint and a process in which the integrated speed ratio ωθP _int / ωθH is calculated. In FIG. 17, for the sake of explanation, a block diagram (see FIG. 7) showing a process in which the turning angle calculation unit 76 calculates the turning angle of the steered wheels 24 is outside the range surrounded by the broken line. Show.

In the process of calculating the output angular velocity ωθP in each universal joint, first, as shown in FIG. 17, the steering angular velocity ωθH calculated in step S360 is input to the above equation (18).
Then, the current steering angle θH detected by the steering angle sensor 34 when the ignition switch is turned on is inputted as “θ _In ” to the universal joint output angular velocity calculation model corresponding to the universal joint 7. Thereby, the output angular velocity ωθP ₁ at the universal joint 7 is calculated. In FIG. 17, a universal joint output angular velocity calculation model corresponding to the universal joint 7 is shown with a reference “7VR”.

Here, "alpha _1" and "theta _offset1" in universal joint output angular velocity calculating model corresponding to the universal joint 7, the "alpha _1" and "theta _offset1" in universal joint output angle calculation model corresponding to the universal joint 7 Equivalent. The same applies to the other universal joints (11, 19, 23).
Next, the output angle θ _out of the universal joint 7 calculated by the turning angle calculation unit 76 is input to the universal joint output angular velocity calculation model corresponding to the universal joint 11 as “θ _In ”. Thereby, the output angular velocity ωθP ₂ at the universal joint 11 is calculated. In FIG. 17, a universal joint output angular velocity calculation model corresponding to the universal joint 11 is shown with a reference “11VR”.

Then, the turning angle calculation turning-side clutch angle Pθcl_out calculated by the turning angle calculation unit 76 is input as “θ _In ” to the universal joint output angular velocity calculation model corresponding to the universal joint 19. Thereby, the output angular velocity ωθP ₃ at the universal joint 19 is calculated. In FIG. 17, a universal joint output angular velocity calculation model corresponding to the universal joint 19 is shown with a reference “19VR”.
Next, the output angle θ _out of the universal joint 19 calculated by the turning angle calculation unit 76 is input as “θ _In ” to a universal joint output angular velocity calculation model corresponding to the universal joint 23. Thereby, the output angular velocity ωθP ₄ at the universal joint 23 is calculated. In FIG. 17, a universal joint output angular velocity calculation model corresponding to the universal joint 23 is shown with a symbol “23VR”.
After calculating the output angular velocities ωθP ₁ , ωθP ₂ , ωθP ₃ , ωθP ₄ at the universal joints (7, 11, 19, 23) as described above, these calculated output angular velocities are input to the following equation (20). Then, the integrated speed ratio ωθP _int / ωθH is calculated.

As described above, the torque ratio calculation unit 80 is based on the values obtained by inputting the current steering angle θH and the steered wheel side output angle used by the steered angle calculation unit 76 in calculating the steered angle to the universal joint output angular velocity calculation model. The output angular velocity ωθP is calculated. In addition, the input / output torque ratio T _ratio is calculated based on the ratio between the calculated output angular velocity ωθP and the calculated steering angular velocity ωθH.
Further, the torque ratio calculation unit 80 calculates the input / output torque ratio T _ratio based on the value input to the universal joint output angular velocity calculation model using the turning angle calculation turning side clutch angle Pθcl_out as the steering wheel side input angle. To do.

(Operation)
Next, an example of an operation performed using the vehicle steering control device 1 of the present embodiment will be described with reference to FIGS. 1 to 16 and FIG. FIG. 18 is a time chart showing the operation of the vehicle using the vehicle steering control device 1 of the present embodiment.
The time chart shown in FIG. 18 shows a state where the ignition switch is on, such as when the vehicle is running, and the torque transmission path is mechanically separated to control the SBW system (“SBW” shown in the figure). Starts during system control ”). The control of the SBW system is, for example, control of the turning angle in accordance with the vehicle speed, such as control (variable gear control) for reducing the degree of change of the turning angle with respect to the steering angle when traveling at high speed than when traveling at low speed. . In addition, the control of the SBW system includes the relationship between the steering angle stored in the neutral position storage unit 60 and the turning motor rotation angle, the current steering angle θH detected by the steering angle sensor 34, and the vehicle speed detected by the vehicle speed sensor 50. To do.

Then, for example, at the time t1 when the driver operates the control changeover switch to switch from the control by the SBW system to the EPS control, the control of the SBW system is finished, and the process at the start of the EPS control (“ “Processing at the start of EPS control”).
The process performed at time t1 is a process of switching the clutch 6 to the engaged state (“clutch engagement” shown in the drawing) to mechanically connect the torque transmission path, and further calculating and storing the clutch angle deviation dθCL. In addition to this, at time t1, a process of calculating the input / output torque ratio is performed.
And EPS control is implemented using the command value of the assist torque calculated based on the calculated input-output torque ratio.

At the time t2 when the EPS control is being performed ("EPS system control" shown in the figure) is switched from the EPS control to the control by the SBW system, the process at the time of starting the SBW system control (" Processing at the time of starting the SBW system ").
Note that switching from EPS control to control by the SBW system is performed, for example, when the driver operates a control changeover switch.
The processing performed at time t2 is processing performed before switching the clutch 6 to the disengaged state (“clutch disengagement” shown in the figure), processing for calculating the steered angle of the steered wheels 24, steering angle and steered motor. This process corrects or maintains the relationship with the rotation angle.

When the process of calculating the steered angle of the steered wheels 24 and the process of correcting or maintaining the relationship between the steering angle and the steered motor rotation angle are finished, the clutch 6 in the connected state is switched to the released state, and the SBW system Control is started ("SBW system in control" shown in the figure).
Here, in the vehicle steering control apparatus 1 of the present embodiment, at the start of EPS control, the steering angular velocity ωθH and the output angular velocities ωθP ₁ , ωθP ₂ , ωθP ₃ , and the universal joints (7, 11, 19, 23), ωθP ₄ is calculated. In addition to this, the reciprocal of the integrated speed ratio ωθP _int based on the calculated output angular speeds ωθP _{1 to} ωθP ₄ and the integrated speed ratio ωθP _int / ωθH calculated using the steering angular speed ωθH is calculated, and the input / output torque ratio T _ratio Is calculated.

Then, the command value of the assist torque is calculated using at least one of the calculated input / output torque ratio T _ratio and the input / output torque ratio map stored in the torque ratio map storage unit 84, and the calculated assist torque EPS control is performed based on the command value.
That is, in the vehicle steering control device 1 of the present embodiment, the input / output torque ratio T _ratio is set using the relationship between the steering wheel side input angle and the steered wheel side output angle and the relationship between the steering angular velocity ωθH and the output angular velocity ωθP. calculate.

Therefore, even when torque fluctuation occurs in the torque transmission path, the ratio of the steering angular speed ωθH and the output angular speed ωθP is the ratio of the input / output torque ratio T _ratio corresponding to the change in the steering angle input to the torque transmission path. It is possible to calculate. For this reason, it is possible to estimate the torque fluctuation generated in the torque transmission path due to the inconstant velocity of the universal joint, and it is possible to appropriately control the turning angle with respect to the steering operation of the driver in the EPS control. It becomes.
The steering angle sensor 34 described above corresponds to a steering angle detection unit.

Moreover, the steering motor angle sensor 16 mentioned above respond | corresponds to a steering actuator rotation angle detection part.
The pinion shaft torque sensor 46t described above corresponds to a steering torque detector.
In addition, as described above, the vehicle steering control method implemented by the operation of the vehicle steering control device 1 according to the present embodiment determines the command value of the assist torque based on the torque sensor value Vtp and the input / output torque ratio T _ratio. This is a calculation method. Here, the input / output torque ratio T _ratio is calculated based on the integrated speed ratio ωθP _int / ωθH, which is the _ratio of the steering angular speed ωθH and the output angular speed ωθP.

(Effects of the first embodiment)
In the present embodiment, the following effects can be obtained.
(1) The torque ratio calculation unit 80 calculates the input / output torque ratio T _ratio based on the integrated speed ratio ωθP _int / ωθH which is the ratio of the steering angular speed ωθH and the output angular speed ωθP. In addition to this, the assist torque calculation unit 86 assists the turning of the steered wheels 24 in accordance with the steering state of the steering wheel 32 based on the torque sensor value Vtp and the input / output torque ratio T _ratio. The command value of the assist torque output from is calculated.
For this reason, even if a torque fluctuation occurs in the torque transmission path, the ratio of the steering angular speed ωθH and the output angular speed ωθP, and the input / output torque ratio T according to the change speed of the steering angle input to the torque transmission path. Based on the _ratio , the torque fluctuation can be estimated.

As a result, in the EPS control, it is possible to calculate the command value of the assist torque based on the input / output torque ratio corresponding to the torque fluctuation. Thereby, even if a torque fluctuation occurs in the torque transmission path, the steered motor 2 can be appropriately controlled with respect to the driver's steering operation.
Here, the torque fluctuation generated in the torque transmission path is caused by the following factors.
The two shafts connected using the universal joint are in a state in which the phases of the rotation angles are different from each other due to the inconstant velocity of the universal joint. As a result, torque fluctuations that are difficult to predict are generated in the two shafts connected using the universal joint due to the unequal speed of the universal joint. For this reason, the torque transmitted through the torque transmission path varies as the steering angle input to the torque transmission path changes.

(2) The universal joint output angular velocity calculation model is a model equation represented by the above equation (18).
As a result, it is possible to reduce the calculation load when calculating the output angular velocity ωθP, and thus it is possible to reduce the calculation load when calculating the input / output torque ratio T _ratio .

(3) Based on the value input by the torque ratio calculation unit 80 to the universal joint output angle calculation model, the turning angle calculation turning side clutch angle Pθcl_out obtained by adding the clutch angle deviation dθCL to the steering side clutch angle θcl_in. The output torque ratio T _ratio is calculated. In addition, the assist torque calculation unit 86 calculates an assist torque command value based on the input / output torque ratio T _ratio calculated by the torque ratio calculation unit 80 in a state where the clutch 6 is switched to the connected state.
For this reason, even if a torque fluctuation occurs in the torque transmission path, the torque fluctuation is estimated based on the input / output torque ratio T _ratio according to the clutch angle deviation dθCL in a state where the clutch 6 is switched to the connected state. It becomes possible.
As a result, even when the engagement angle in the coupled state of the clutch 6 is changed, the steered motor 2 is appropriately controlled with respect to the driver's steering operation according to the torque fluctuation generated in the torque transmission path. Is possible.

(4) When the clutch angle deviation dθCL calculated by the clutch angle deviation calculating unit 70 is changed by the torque ratio map storage unit 84, the stored torque ratio map is converted to an input / output torque ratio corresponding to the changed clutch angle deviation dθCL. Change to a map. In addition, the assist torque calculation unit 86 calculates an assist torque command value based on the input / output torque ratio map stored in the torque ratio map storage unit 84.
Therefore, it is possible to calculate the assist torque command value according to the characteristics of the input / output torque ratio map that changes depending on the difference in the engagement angle in the engaged state of the clutch 6.
As a result, even when the engagement angle in the connected state of the clutch 6 changes, the steered motor 2 can be appropriately controlled with respect to the driver's steering operation according to the characteristics of the input / output torque ratio map. It becomes possible.

(5) The fluctuation of the input / output torque ratio T _ratio calculated by the torque ratio calculation unit 80 while the current steering angle θH changes with a change width of 180 degrees and the current steering angle θH. Correspondingly, an input / output torque ratio map is generated. In addition, the assist torque calculator 86 calculates an assist torque command value based on the input / output torque ratio map generated by the torque ratio map generator 82.
For this reason, an input / output torque ratio map is generated based on the input / output torque ratio T _ratio with respect to the current steering angle, which causes fluctuations for one cycle while the current steering angle changes from 0 [°] to 180 [°] It becomes possible to do.
As a result, even if a torque fluctuation occurs in the torque transmission path, it is possible to estimate the torque fluctuation based on the input / output torque ratio map showing the fluctuation for one cycle of the input / output torque ratio T _ratio. Become.

(6) The assist torque calculation unit 86 corrects the torque sensor value Vtp with the input / output torque ratio T _ratio calculated by the torque ratio calculation unit 80, and calculates the command value of the assist torque.
Therefore, it is possible to correct the torque applied by the driver to the steering wheel 32 in accordance with the torque fluctuation generated in the torque transmission path, and to calculate the assist torque command value.
As a result, even if torque fluctuation occurs in the torque transmission path, the steering motor 2 is appropriately applied to the steering operation of the driver according to the torque applied to the steering wheel 32 by the driver and the torque fluctuation. It becomes possible to control to.

(7) In the vehicle steering control method of the present embodiment, the input / output torque ratio T _ratio calculated based on the torque sensor value Vtp and the integrated speed ratio ωθP _int / ωθH that is the ratio of the steering angular speed ωθH and the output angular speed ωθP. Based on the above, a command value for the assist torque is calculated.
For this reason, even if a torque fluctuation occurs in the torque transmission path, the ratio of the steering angular speed ωθH and the output angular speed ωθP, and the input / output torque ratio T according to the change speed of the steering angle input to the torque transmission path. Based on the _ratio , the torque fluctuation can be estimated.
As a result, in the EPS control, it is possible to calculate the command value of the assist torque based on the input / output torque ratio corresponding to the torque fluctuation. Thereby, even if a torque fluctuation occurs in the torque transmission path, the steered motor 2 can be appropriately controlled with respect to the driver's steering operation.

(Modification)
(1) In this embodiment, the torque transmission path includes four universal joints (7, 11, 19, 23). However, the present invention is not limited to this, and the number of universal joints is, for example, that of a vehicle. Any number corresponding to the layout may be used.
In this case, for example, when both the steering-side universal joint and the steered-side universal joint are formed by only one universal joint, the steered angle of the steered wheels 24 is calculated using the following formula (21).

(2) In the present embodiment, the vehicle is configured to include the steering side clutch angle calculation unit 66, the steered side clutch angle calculation unit 68, and the clutch angle deviation calculation unit 70. However, the present invention is not limited to this. That is, for example, after the vehicle is shipped, the steering side clutch angle, the steering side clutch angle, and the clutch are adjusted using the equipment outside the vehicle in a maintenance shop with both the current steering angle and the actual turning angle adjusted to the neutral position. An angular deviation may be calculated. In addition, the calculated clutch angle deviation may be input to the clutch angle deviation storage unit 72 by cable connection or the like, and the clutch angle deviation is stored via a storage medium such as a non-volatile memory. You may memorize | store in the part 72. FIG.

(3) In the present embodiment, the steering torque detector is formed by the pinion shaft torque sensor 46t, but the configuration of the steering torque detector is not limited to this. That is, for example, the steering torque detector may be formed by at least one of the steering torque sensor 36 and the steering motor torque sensor 2t. Here, when the steering torque detector 2t is formed by the steering motor torque sensor 2t, steering that is the torque that the driver is applying to the steering wheel 32 the steering motor torque detected by the steering motor torque sensor 2t. Process to convert to torque.

(4) In the present embodiment, in the process of calculating the steered side clutch angle θcl_out, the turning motor rotation angle at the time when the ignition switch is turned off is set as the reverse input angle tanθ _In of the universal joint 23 as described above. Entered in (2). However, the process for calculating the steered side clutch angle θcl_out is not limited to this.
That is, the value obtained by adding the offset component of the steered-side universal joint (19, 23) to the steered-motor universal angle (19, 23) at the time when the ignition switch is turned off is used as the reverse input angle tanθ _In of the universal joint 23 as described above. You may input into Formula (2).

(5) In the present embodiment, in the process of calculating the steering-side clutch angle θcl_out, the turning motor rotation angle at the time when the ignition switch is turned off is set as the reverse input angle tan θ _In of the universal joint 23 as described above. Entered in (2). However, the process for calculating the steered side clutch angle θcl_out is not limited to this.
That is, based on the torque sensor value Vtp and the torque sensor model, the torsion angles of the steered side shaft and the steered side universal joints (19, 23) are subtracted from the steered motor rotation angle when the ignition switch is turned off. The calculated value is calculated. Then, this calculated value may be input to the above equation (2) as the reverse input angle tan θ _In of the universal joint 23. The steered side shaft is the clutch output shaft 17, the steered side intermediate shaft 21, and the pinion shaft 25.

(6) In the present embodiment, the input / output torque ratio T _ratio is calculated using a universal joint output angular velocity calculation model that is a model expression showing the relationship between the steering angular velocity ωθH and the output angular velocity ωθP for one universal joint. However, the present invention is not limited to this. That is, instead of the universal joint output angular velocity calculation model, the input / output torque ratio T _ratio may be calculated using a comprehensive universal joint output angular velocity calculation model represented by the following equation (22).

Here, the general universal joint output angular velocity calculation model is a model equation in which a model equation indicating the relationship between the steering angular velocity ωθH and the output angular velocity ωθP for one universal joint is replaced with an equation for a plurality of universal joints. It is.
The general universal joint output angular velocity calculation model is a model formula showing the relationship between the steering angular velocity and the total output angle velocity. The output angle total speed is a speed based on the total value of the change amount of the steered wheel side output angle within the angular speed calculation time Δt output through all the universal joints (7, 11, 19, 23). In addition, in said Formula (22), the model formula which made object the two universal joints (7,11) among all the universal joints (7,11,19,23) is shown.
In this case, it is possible to reduce the number of processes (steps) performed when calculating the input / output torque ratio T _ratio .

(7) In the present embodiment, the vehicle including the vehicle steering control device 1 is a vehicle to which the SBW system is applied, but is not limited thereto. That is, the configuration of the vehicle may be a configuration in which the torque transmission path is always mechanically connected by the universal joint without applying the SBW system and without the clutch 6.
In this case, the process in which the torque ratio calculation unit 80 calculates the input / output torque ratio does not perform the process from step S300 to step S330 (see FIG. 16). That is, when the torque ratio calculation unit 80 starts the process of calculating the input / output torque ratio, the process of step S340 is performed.

(8) In the present embodiment, in the process in which the torque ratio calculation unit 80 calculates the input / output torque ratio, the turning angle of the steered wheels 24 at the time when the clutch 6 is in the engaged state is used as the current estimated value of the pinion angle. The calculation process was performed (see step S350 in FIG. 16). However, the process by which the torque ratio calculation unit 80 calculates the input / output torque ratio is not limited to this. That is, the steering angle of the steered wheels 24 at the time when the clutch 6 is in the engaged state may be calculated as the current detected value of the pinion angle. In this case, the current detected value of the pinion angle is calculated based on the turning motor rotation angle detected by the turning motor angle sensor 16. However, as in this embodiment, by performing the process of calculating the current estimated value of the pinion angle, the influence of the calculation error is reduced compared to the case of performing the process of calculating the current detected value of the pinion angle. It becomes possible to make it.

(9) In the present embodiment, in the EPS control, the assist torque is output from the steered motor 2 (steered actuator). However, the present invention is not limited to this. That is, in the EPS control, the assist torque may be output from the reaction force motor 8 (reaction force actuator). Moreover, in EPS control, it is good also as a structure which uses the steering motor 2 and the reaction force motor 8, and cooperates the steering motor 2 and the reaction force motor 8, and outputs assist torque.

1 Steering control device for vehicle 2 Steering motor (steering actuator)
2t Steering motor torque sensor 4 Steering motor controller 6 Clutch 7, 11 Universal joint (steering side universal joint)
19, 23 Universal joint (steering side universal joint)
8 Reaction force motor (Reaction force actuator)
DESCRIPTION OF SYMBOLS 10 Reaction force motor control part 16 Steering motor angle sensor 24 Steering wheel 32 Steering wheel 34 Steering angle sensor 40 Clutch plate 42 Steering shaft 44 Pinion shaft 46 Pinion 46t Pinion shaft torque sensor 50 Vehicle speed sensor 52 Engine controller 54 Command calculating part 56 Anti-reverse Force servo control unit 58 Clutch control unit 60 Neutral position storage unit 62 Steering motor current command calculation unit 64 Clutch state switching unit 66 Steering side clutch angle calculation unit 68 Steering side clutch angle calculation unit 70 Clutch angle deviation calculation unit 72 Clutch angle Deviation storage unit 74 Steering angle storage unit 76 Steering angle calculation unit 78 EPS control block 80 Torque ratio calculation unit 82 Torque ratio map generation unit 84 Torque ratio map storage unit 86 Assist torque calculation unit MA Steering side previous processing content storage unit MB anti Power side last processing content storage

Claims (5)

A universal joint that connects a torque transmission path between the steering wheel and the steered wheel, and an actuator that outputs an assist torque that is a torque for assisting the steering of the steered wheel in accordance with the steering operation of the driver. A vehicle steering control device comprising:
The actuator that outputs the assist torque is a steered actuator that steers the steered wheel,
A steering angle detector for detecting a steering angle of the steering wheel;
A steering torque detector for detecting a steering torque that is a torque applied to the steering wheel;
A torque ratio calculation unit for calculating an input / output torque ratio based on a ratio between a steering angle input to the universal joint and an output angle output from the universal joint based on the input steering angle;
An assist torque calculator that calculates a command value of the assist torque based on the steering torque detected by the steering torque detector and the input / output torque ratio calculated by the torque ratio calculator;
A steering wheel side input angle that is an angle based on a steering angle input to the universal joint, and a steered wheel side output angle that is an angle obtained by outputting the steering wheel side input angle to the steered wheel side via the universal joint; The turning angle for calculating the turning angle of the steered wheels based on a value obtained by inputting the steering angle detected by the steering angle detection unit to a preset universal joint output angle calculation model that is a model formula indicating the relationship of A calculation unit;
A clutch that switches between an open state that mechanically separates the torque transmission path and a connection state that mechanically connects the torque transmission path;
A steering-side universal joint that mechanically connects between the steering wheel and the clutch;
A steering-side universal joint that mechanically connects the steered wheel and the clutch;
The steering angle detected by the steering angle detector is a rotation angle on the steering wheel side of the torque transmission path based on a steering output angle that is a rotation angle transmitted to the clutch via the steering universal joint. A steering side clutch angle calculating unit for calculating a certain steering side clutch angle;
A turning actuator rotation angle detector that detects a turning actuator rotation angle that is a rotation angle of the turning actuator;
The torque transmission path is based on a turning-side reverse output angle, which is a turning angle transmitted to the clutch via the turning-side universal joint, by the turning actuator rotation angle detected by the turning actuator rotation angle detection unit. A steered side clutch angle calculating unit that calculates a steered side clutch angle that is a rotation angle on the steered wheel side of
A clutch angle deviation calculation unit that calculates a clutch angle deviation that is a deviation between the steering side clutch angle calculated by the steering side clutch angle calculation unit and the steering side clutch angle calculated by the steering side clutch angle calculation unit; Prepared,
The torque ratio calculating unit is a universal joint output angular velocity in which the steering angle detected by the steering angle detecting unit and the steered wheel side output angle used by the steered angle calculating unit in calculating the steered angle are set in advance. Based on a value input to the calculation model, an output angular velocity based on a change amount of the steered wheel side output angle within an angular velocity calculation time which is a preset time is calculated, and further, the calculated output angular velocity and the angular velocity calculation are calculated. The ratio of the steering angular velocity based on the amount of change in the steering angle of the steering wheel over time and the clutch angle deviation calculated by the clutch angle deviation calculation unit to the steering side clutch angle calculated by the steering side clutch angle calculation unit. before based steering angle calculation steered side clutch angle obtained by adding the value entered in the universal joint output angular velocity calculating model as the steering wheel input angle It calculates the output torque ratio,
The assist torque calculation unit calculates a command value of the assist torque based on an input / output torque ratio calculated by the torque ratio calculation unit in a state where the clutch is switched to a connected state.
The universal joint output angular velocity calculation model is a model formula showing a relationship between the steering angular velocity and the output angular velocity. The universal joint output angular velocity calculation model includes the steering wheel side input angle, the steered wheel side output angle, the output angular velocity, the steering angular velocity, and the input side axis and the output side of the universal joint in plan view. A model equation showing a relationship between a joint angle that is an angle formed by an axis and a phase angle that indicates a torsion angle of an output shaft with respect to an input shaft of the universal joint, where the steering wheel side input angle is θ _in, and When the steering wheel-side output angle is θ _out , the output angular velocity is ωθP, the steering angular velocity is ωθH, the joint angle is α, and the phase angle is θ _offset , the following expression is used. The vehicle steering control device according to claim 1.

The torque transmission path is connected by a plurality of universal joints,
Instead of the universal joint output angular velocity calculation model, the total output angle based on the total value of the steering angular velocity and the change amount of the steered wheel side output angle within the angular velocity calculation time respectively output via the plurality of universal joints The vehicle steering control apparatus according to claim 1 or 2, wherein an overall universal joint output angular velocity calculation model, which is a model formula indicating a relationship between the velocity and the velocity, is used. The assist torque calculation unit corrects the steering torque detected by the steering torque detection unit with an input / output torque ratio calculated by the torque ratio calculation unit, and calculates a command value of the assist torque. The vehicle steering control device according to any one of claims 1 to 3 . A clutch that switches a torque transmission path between a steering wheel and a steered wheel between an open state in which the torque transmission path is mechanically separated and a connection state in which the torque transmission path is mechanically coupled; and the steering wheel And a steering-side universal joint that mechanically connects between the clutch and the clutch, and a steering-side universal joint that mechanically connects between the steered wheel and the clutch. A vehicle steering control method for outputting an assist torque, which is a torque for assisting steering of the steered wheels from an actuator,
The actuator that outputs the assist torque is a steered actuator that steers the steered wheel,
Detecting a steering angle of the steering wheel and a steering torque which is a torque applied to the steering wheel;
A steering wheel side input angle that is an angle based on a steering angle input to the universal joint, and a steered wheel side output angle that is an angle obtained by outputting the steering wheel side input angle to the steered wheel side via the universal joint; The turning angle of the steered wheels is calculated based on a value obtained by inputting the detected steering angle to a preset universal joint output angle calculation model that is a model formula indicating the relationship of
Based on the steering side output angle, which is the rotation angle transmitted to the clutch via the steering side universal joint, the detected steering angle, the steering side clutch angle, which is the rotation angle on the steering wheel side of the torque transmission path. To calculate
Detecting the turning angle of the turning actuator which is the turning angle of the turning actuator;
The rotation angle of the torque transmission path on the steered wheel side based on the steered side reverse output angle, which is the rotation angle transmitted to the clutch via the steered side universal joint. Calculate the steering side clutch angle which is
Calculating a clutch angle deviation which is a deviation between the calculated steering side clutch angle and the calculated steered side clutch angle;
An angular velocity calculation that is a preset time based on a value that is input to a preset universal joint output angular velocity calculation model for the detected steering angle and the steered wheel side output angle used in the calculation of the steered angle. Calculate the output angular velocity based on the change amount of the steered wheel side output angle within the time,
Based on the ratio of the calculated output angular velocity and the steering angular velocity based on the amount of change in the steering angle of the steering wheel within the angular velocity calculation time, the steering angle input to the universal joint, and the input steering The steering angle clutch for turning angle calculation obtained by adding the calculated clutch angle deviation to the ratio of the output angle output from the universal joint based on the angle and the calculated steering clutch angle is the steering wheel side. Calculate the input / output torque ratio based on the value input to the universal joint output angular velocity calculation model as the input angle ,
A command value for the assist torque is calculated based on the detected steering torque, the calculated input / output torque ratio, and the input / output torque ratio calculated in a state where the clutch is switched to a connected state ,
The universal joint output angular velocity calculation model is a model formula showing a relationship between the steering angular velocity and the output angular velocity.

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