JP6774315B2 - Vehicle steering device - Google Patents

Description

The present invention relates to a vehicle steering device capable of setting a steering angle by an electric motor independently of steering input by a driver.

In vehicles such as automobiles, a steering device has been developed that generates an assist torque that assists the driver's steering force in response to the driver's steering, and that automatically steers independently of the driver's steering input. ing.

As disclosed in Patent Document 1, for example, such a steering device transmits the rotation of the steering wheel to the rack and pinion mechanism via a torsion bar, and controls the rack stroke movement amount by an electric motor. Known as a steering device.

Japanese Unexamined Patent Publication No. 2006-199075

As disclosed in Patent Document 1, some electric power steering devices use a DC brushless motor as an electric motor, and this DC brushless motor is based on a signal of a rotation position sensor that detects the rotation position of the motor. Be controlled. Further, the steering angle by the electric motor can be estimated by detecting the motor rotation angle based on the signal from the rotation position sensor.

In this case, the motor rotation angle based on the signal from the rotation position sensor is the rotation angle from the zero point position that is arbitrarily set. Therefore, it is necessary to set the zero point position of the rotation position sensor prior to the start of running of the vehicle. Become. The zero position of the rotation position sensor is usually set in the initialization process prior to the start of traveling when the ignition switch is turned on.

For example, when the ignition switch is turned on, the steering angle sensor detects the rotation angle (steering angle) of the steering wheel as an absolute rotation angle from a predetermined reference position. Then, the zero point position of the rotation position sensor is set so that the steering angle by the electric motor matches the steering angle detected by the steering angle sensor.

However, the rudder angle detected by the rudder angle sensor may include a rudder angle component due to the twist of the torsion bar. If the zero position of the rotation position sensor is set with a steering angle that includes components caused by the twist of the torsion bar, the steering angle of the steering wheel at normal times and the steering angle of the electric motor will deviate, and automatic steering will be used to set the target path. When traveling along the route, an offset may occur with respect to the target route, and the controllability may deteriorate.

The present invention has been made in view of the above circumstances, and is a vehicle steering device capable of eliminating the deviation between the steering angle of the steering wheel and the steering angle of the electric motor and improving the controllability of automatic steering by the electric motor. Is intended to provide.

The vehicle steering device according to the first aspect of the present invention is a vehicle steering device in which the steering angle by the electric motor can be set independently of the steering input by the driver, and the zero point position which is a reference of the motor rotation angle of the electric motor. When it is determined that the zero point position setting unit for setting, the correction execution condition determination unit for determining whether or not the correction execution condition for correcting the steering angle by the electric motor is satisfied, and the correction execution condition for determining the correction execution condition are satisfied. , The correction amount calculation unit that calculates the steering angle difference between the steering angle of the steering wheel and the steering angle by the electric motor estimated based on the zero point position as the correction amount for the steering angle by the electric motor, and the correction execution. When it is determined that the conditions are satisfied, the correction unit includes a correction unit that corrects the steering angle by the electric motor with the correction amount, and the correction execution condition determination unit includes the input torque to the steering wheel and the steering angle of the steering wheel. When at least one of the steering angle difference between the steering angle and the steering angle of the electric motor and the steering angle and the steering speed of the steering wheel satisfy a predetermined condition, it is determined that the correction execution condition is satisfied.
The vehicle steering device according to the second aspect of the present invention is a vehicle steering device in which the steering angle by the electric motor can be set independently of the steering input by the driver, and the zero point position which is a reference of the motor rotation angle of the electric motor. When it is determined that the zero point position setting unit for setting, the correction execution condition determination unit for determining whether or not the correction execution condition for correcting the steering angle by the electric motor is satisfied, and the correction execution condition for determining the correction execution condition are satisfied. , The correction amount calculation unit that calculates the steering angle difference between the steering angle of the steering wheel and the steering angle by the electric motor estimated based on the zero point position as the correction amount for the steering angle by the electric motor, and the correction execution. When it is determined that the condition is satisfied, a correction unit for correcting the steering angle by the electric motor with the correction amount is provided, and when the steering angle is corrected by the electric motor, a limit is provided on the steering angle change due to the correction amount.
The vehicle steering device according to the third aspect of the present invention is a vehicle steering device in which the steering angle by the electric motor can be set independently of the steering input by the driver, and the zero point position which is a reference of the motor rotation angle of the electric motor. When it is determined that the zero point position setting unit for setting, the correction execution condition determination unit for determining whether or not the correction execution condition for correcting the steering angle by the electric motor is satisfied, and the correction execution condition for determining the correction execution condition are satisfied. , The correction amount calculation unit that calculates the steering angle difference between the steering angle of the steering wheel and the steering angle by the electric motor estimated based on the zero point position as the correction amount for the steering angle by the electric motor, and the correction execution. When it is determined that the condition is satisfied, a correction unit for correcting the steering angle by the electric motor with the correction amount is provided, and when the steering angle is corrected by the electric motor, the steering angle after correction by the correction amount is limited. ..

According to the present invention, it is possible to eliminate the deviation between the steering angle of the steering wheel and the steering angle of the electric motor, and improve the controllability of automatic steering by the electric motor.

Configuration diagram of steering control system according to the first embodiment of the present invention. Same as above, explanatory diagram showing the steering angle and EPS steering angle at normal times. Same as above, explanatory diagram showing the deviation of the EPS rudder angle when a component caused by the twist of the torsion bar is included. Same as above, time chart showing correction timing and correction pattern of EPS rudder angle Same as above, explanatory diagram showing correction timing and correction amount Same as above, flowchart of EPS rudder angle correction processing Same as above, explanatory diagram showing re-correction of EPS rudder angle Flow chart of EPS steering angle correction processing according to the second embodiment of the present invention. Same as above, a time chart showing the timing of steering control when the rudder angle difference is less than the threshold value. Same as above, a time chart showing the timing of steering control when the rudder angle difference is equal to or greater than the threshold value.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 indicates an electric power steering (EPS) device as a steering device in which the steering angle can be set independently of the steering input by the driver. In this EPS device 1, the steering shaft 2 is rotatably supported by a vehicle body frame of a vehicle such as an automobile (not shown) via a steering column 3, one end of which extends toward the driver's seat, and the other end. It extends to the engine room side.

A steering wheel 4 is fixedly installed at the driver's seat side end of the steering shaft 2, and a steering angle sensor 22 is arranged on the outer peripheral side of the steering shaft 2 to which the steering wheel 4 is connected. The steering angle sensor 22 is configured to include, for example, two sets of magnetic resistance elements for detecting the rotation of a magnet built in a detection gear, and is a reference rotation position of the steering wheel 4 (for example, in a vehicle straight-ahead state). The rotation position of the upper part of the steering wheel 4) is set in advance, and the rotation angle (rudder angle) and the rotation direction (steering direction) from the preset fixed reference position are based on the magnetic change generated by the rotation of the detection gear. ) Can be detected.

Further, a torsion bar 2a is interposed in the middle of the steering shaft 2, and a pinion shaft 5 is continuously provided at an end extending toward the engine room side. A torque sensor 23 is arranged on the outer peripheral side of the torsion bar 2a. The torque sensor 23 can detect the steering torque due to the steering of the driver by detecting the displacement between the steering wheel 4 side and the pinion shaft 5 side generated around the axis of the steering shaft 2 due to the twist of the torsion bar 2a. ..

On the other hand, in the engine room, a steering gear box 6 extending in the vehicle width direction is arranged, and a rack shaft 7 is inserted and supported in the steering gear box 6 so as to be reciprocally movable. A rack and pinion type steering gear mechanism is formed by engaging a pinion formed on the pinion shaft 5 with a rack (not shown) formed on the rack shaft 7.

Further, both left and right ends of the rack shaft 7 are projected from the end portions of the steering gear box 6, and front knuckles 9 are continuously provided at the end portions via the tie rods 8. The front knuckle 9 rotatably supports the left and right wheels 10L and 10R as steering wheels, and is rotatably supported by the vehicle body frame. Therefore, when the steering wheel 4 is operated to rotate the steering shaft 2 and the pinion shaft 5, the rack shaft 7 moves in the left-right direction due to the rotation of the pinion shaft 5, and the front knuckle 9 moves to the kingpin shaft (shown in the figure). The left and right wheels 10L and 10R are steered in the left-right direction by rotating around the wheel.

Further, an electric power steering motor 12 is continuously provided on the pinion shaft 5 via an assist transmission mechanism 11 including a reduction gear mechanism or the like. The electric power steering motor 12 is, for example, an electric motor including a DC brushless motor having a stator fixed to a case and a rotor that rotates inside the stator, and rotation of the rotor of the electric motor is via an assist transmission mechanism 11. It is converted into the axial movement of the rack shaft 7.

The electric power steering motor 12 has a built-in rotation position sensor 24 that detects the rotation position of the rotor. The rotation position sensor 24 detects the rotation position of the rotor by, for example, a rotary encoder or the like, and a signal from the rotation position sensor 24 is input to the steering control device 50.

The steering control device 50 controls the current of the electric power steering motor 12 according to the rotation position of the rotor based on the signal from the rotation position sensor 24, and recognizes the steering angle of the steering control from the rotation position of the rotor. The recognition of the steering angle based on the signal from the rotation position sensor 24 will be described later.

The steering control device 50 is a control unit composed mainly of a microcomputer, and includes an engine control device and a transmission (not shown) including an external environment recognition device 100 that recognizes the external environment of the vehicle and acquires driving environment information. It is connected to other control units such as a control device and a brake control device via a communication bus 150 that forms an in-vehicle network. The steering control device 50 is connected to a vehicle speed sensor 21 that detects the vehicle speed, sensors such as the above-mentioned steering angle sensor 22, torque sensor 23, and rotation position sensor 24, and switches such as the ignition switch 25.

The external environment recognition device 100 includes detection information of objects around the own vehicle by various devices such as an in-vehicle camera, millimeter wave radar, and laser radar, traffic information acquired by infrastructure communication such as road-to-vehicle communication and vehicle-to-vehicle communication, and a GPS satellite. Height including positioning information of own vehicle position based on signals from, etc., road shape data such as road curvature, lane width, road shoulder width, and driving control data such as road azimuth angle, lane marking line type, number of lanes, etc. Recognize the external environment around the vehicle from detailed map information. In the present embodiment, the recognition of the front environment by the in-vehicle camera and the image recognition device will be mainly described as the external environment recognition device 100, and the in-vehicle camera is two cameras that capture the same object from different viewpoints. It is a stereo camera that is configured.

The two cameras that make up the stereo camera are shutter-synchronized cameras that have image sensors such as CCD and CMOS. For example, they are arranged in the vicinity of the room mirror inside the front window in the upper part of the vehicle interior with a predetermined baseline length. ing.

The processing of the image data from the stereo camera in the external environment recognition device 100 is performed as follows, for example. First, a distance image having distance information is generated from a set of stereo image pairs in the traveling direction of the own vehicle captured by the camera from the amount of deviation of the corresponding positions.

In recognizing lane markings such as white lines, based on the knowledge that lane markings are brighter than the road surface, the change in brightness in the width direction of the road is evaluated, and the left and right lane markings in the image plane are evaluated. The position of is specified on the image plane. The position (x, y, z) of this lane marking line in real space is based on the position (i, j) on the image plane and the parallax calculated for this position, that is, based on the distance information. It is calculated from a well-known coordinate conversion formula.

In the present embodiment, the coordinate system in the real space set based on the position of the own vehicle has, for example, the x-axis in the vehicle width direction with the road surface directly below the center of the camera as the origin, as shown in FIG. The vehicle height direction is the y-axis, and the vehicle length direction (distance direction) is the z-axis. At this time, the x-z plane (y = 0) coincides with the road surface when the road is flat. The road model is expressed by dividing the traveling lane of the own vehicle on the road into a plurality of sections in the distance direction and connecting the left and right lane marking lines in each section with a predetermined approximation.

The recognition result of the external environment by the external environment recognition device 100 is transmitted to the steering control device 50 and other control devices. In the driving support control that supports the automatic driving of the own vehicle and the driving of the driver, the steering control device 50 sets a target route on which the own vehicle travels based on the recognition result of the external environment, and follows the target route to travel. , Follow-up steering control is executed via the motor drive unit 20 that drives the electric power steering motor 12, and when steering intervention by the driver's steering wheel operation is detected, the electric power steering motor 12 assists the driver's steering operation. Outputs auxiliary torque.

The target path in the follow-up steering control of the steering control device 50 is set based on the recognition result of the external environment by the external environment recognition device 100. That is, the steering control device 50 calculates the locus of the target point to be followed by the own vehicle, and sets the locus of the target point as the target route. It should be noted that this target route may be set not by the steering control device 50 but by another control device such as the external environment recognition device 100.

For example, in the control of keeping the own vehicle in the center of the lane by following the lane (lane keeping control), the center position of the left and right white lines as the lane marking line in the road width direction is the target point of the target route to be followed. Is set as. Further, in the control of following the preceding vehicle in front of the own vehicle (preceding vehicle following control), the central position in the vehicle width direction of the rear region of the preceding vehicle is set as the target point of the target route to be followed.

The steering control device 50 sets a target steering angle that matches the center position of the own vehicle in the vehicle width direction with the target point on the target path, and the electric power steering motor 12 so that the steering angle of the steering control becomes the target steering angle. Is driven and controlled. In particular, when there is no steering operation of the driver (no steering intervention) and the vehicle automatically follows the preceding vehicle under low speed driving such as in a traffic jam, the steering control device 50 receives a signal from the rotation position sensor 24. Based on this, the steering angle by the electric power steering motor 12 is estimated, and the electric power steering motor 12 is controlled so that the steering angle recognized by this estimation matches the target steering angle.

Specifically, the steering control device 50 estimates the motor rotation angle (rotor rotation angle) θmtr based on the signal from the rotation position sensor 24. Then, as shown in the following equation (1), the electric power steering motor 12 recognizes the value obtained by multiplying the motor rotation angle θmtr by the reduction ratio r of the assist transmission mechanism 11 based on the signal from the rotation position sensor 24. Steering angle (EPS steering angle) θEPS.
θEPS ＝ θmtr × r… (1)

Here, the motor rotation angle θmtr based on the signal from the rotation position sensor 24 is a relative rotation angle from a predetermined position, and is recognized as a rotation angle from a preset zero point position. That is, the rotation position sensor 24 is arbitrarily set unlike the steering angle sensor 22 that can detect the rotation angle (steering steering angle) θSTR of the steering wheel 4 as an absolute rotation angle from a predetermined reference position. It is possible to estimate the rotation angle from the zero point position.

For example, when the rotation position sensor 24 is configured by an incremental rotary encoder, the counter is reset at a predetermined reference position, and the number of pulses from that position is cumulatively added to increase the amount of rotation from the reference position. (Rotation angle) can be estimated. The reference position can be set arbitrarily, and the rotation direction can also be known from the output timings of the two pulse examples having different phases.

Therefore, when the steering control device 50 detects that the ignition switch 25 is turned on, it reads the steering angle θSTR by the steering angle sensor 22 as an initialization process prior to the start of traveling when the ignition is turned on. Then, the zero position of the rotation position sensor 24 is initially set based on the steering angle θSTR.

Specifically, the steering control device 50 applies the steering steering angle θSTR as the EPS steering angle θEPS to the equation (1) assuming that the steering steering angle θSTR read when the ignition is turned on and the EPS steering angle θEPS are equal to each other, and the motor Find the rotation angle θmtr. Then, the position where the motor rotation angle θmtr is set at the rotation position indicated by the rotation position sensor 24 is initially set as the zero point position of the rotation position sensor 24.

When the zero point position is initially set, if the steering steering angle θSTR contains a component caused by the twist of the torsion bar, the zero point position of the rotation position sensor 24 becomes inappropriate, and the steering steering angle θSTR and the EPS steering are normally used. The angle θEPS does not match. As a result, when the follow-up steering control to the preceding vehicle is executed, the own vehicle may be offset with respect to the target route (traveling locus of the preceding vehicle) and run unevenly.

As shown in FIG. 2, normally, the steering angle θSTR by the steering angle sensor 22 (the steering angle shown by the solid line in FIG. 2) and the rotation position sensor 24 in which the zero point position is initially set based on the steering angle θSTR. EPS steering angle θEPS (steering angle shown by a broken line in FIG. 2) is almost equal to. When a component caused by the twist of the torsion bar is included, a clear difference in steering angle due to the twist of the torsion bar 2a may occur in the steering angle θSTR by the steering angle sensor 22.

Therefore, when the ignition is turned on and the component caused by the twist of the torsion bar is included, the EPS rudder angle θEPS at the initial setting shown by the broken line in FIG. 3 is the steering rudder angle θSTR (normal steering) shown by the solid line in FIG. The angle) is deviated by the steering angle difference Δθ1 due to the twist of the torsion bar 2a. As a result, the zero position of the rotation position sensor 24 shifts, and the steering steering angle θSTR and the EPS steering angle θEPS at the normal time do not match.

Therefore, the steering control device 50 includes a zero point position setting unit 51, a correction execution condition determination unit 52, a correction amount calculation unit 53, and a correction unit 54 as functional units related to the correction of the EPS steering angle. The steering control device 50 makes the EPS steering angle θEPS match with the steering steering angle θSTR by these functional units, and enables stable steering control.

When the ignition switch 25 is turned on, the zero point position setting unit 51 reads the steering steering angle θSTR detected by the steering angle sensor 22, and initially sets this steering steering angle θSTR as the EPS steering angle θEPS. Then, the motor rotation angle θmtr of the electric power steering motor 12 is calculated from the initially set EPS steering angle θEPS based on the above equation (1), and the zero position of the rotation position sensor 24 is set from this motor rotation angle θmtr. To do.

After setting the zero point position of the rotation position sensor 24, the motor rotation angle θmtr can be detected from the signal of the rotation position sensor 24 with reference to this zero point position. Then, the EPS steering angle θEPS can be estimated by multiplying the detected motor rotation angle θmtr by the reduction ratio r of the assist transmission mechanism 11.

The correction execution condition determination unit 52 corrects the deviation between the EPS steering angle θEPS based on the zero point position of the rotation position sensor 24 set by the zero point position setting unit 51 and the steering steering angle θSTR detected by the steering angle sensor 22. It is determined whether or not the conditions (J1), (J2), and (J3) shown below are satisfied.

(J1) Steering torque is below the threshold value When the torsion bar 2a is twisted by a predetermined value or more due to the input of the steering torque, accurate correction becomes difficult. Therefore, the condition that the steering torque detected by the torque sensor 23 is equal to or less than the threshold value is set as one of the conditions for performing the correction.

(J2) The deviation between the steering steering angle θSTR and the EPS steering angle θEPS is equal to or greater than the threshold value at which a steering control problem occurs between the steering steering angle θSTR and the EPS steering angle θEPS (for example, 7 degrees or more). If there is a deviation, it is one of the conditions for performing correction.

(J3) At least one of the steering steering angle and the steering steering speed (steering speed; angular velocity of the steering angle) is below the threshold value. If the steering is steered significantly or the steering speed is high, stable correction becomes difficult. Is expected. Therefore, the condition for performing correction is that the steering angle θSTR detected by the steering angle sensor 22 is equal to or less than the threshold value (for example, 20 degrees or less), the steering steering speed is equal to or less than the threshold value (for example, 1 deg / s or less), or both. Let it be one of.

As shown in FIG. 4, the correction according to the above conditions (J1) to (J3) is carried out in the pattern A or the pattern B with the ignition turned on. The pattern A is a pattern in which the correction is performed with the timing at which all the conditions (J1) to (J3) are satisfied (the timing at which the AND of the conditions J1 to J3 is satisfied) as the correction execution condition. On the other hand, the pattern B is a pattern in which the correction is performed with the timing at which the time for satisfying all the conditions (J1) to (J3) has elapsed for a predetermined fixed time as the correction execution condition is satisfied.

It should be noted that the conditions (J1) to (J3) may be individually provided with a determination time for determining whether or not each condition is satisfied.

The correction amount calculation unit 53 calculates the EPS steering angle from the steering steering angle θSTR detected by the steering angle sensor 22 and the motor rotation angle by the rotation position sensor 24 when the correction execution condition determination unit 52 determines that the correction execution condition is satisfied. The deviation from the angle θEPS is calculated as the correction amount of the EPS steering angle. In the calculation of this correction amount (and the steering angle correction by the correction unit 54), after the ignition switch 25 is turned on, the steering angle difference between the steering steering angle θSTR and the EPS steering angle θEPS is the correction execution threshold value He (for example, 2 to 2). If it is 3 times or more, it is executed multiple times.

As described with reference to FIG. 3, when a component caused by twisting of the torsion bar is included when the ignition is turned on, a steering angle difference Δθ1 is generated between the EPS steering angle θEPS and the steering steering angle θSTR. Therefore, after the ignition switch is turned on, the correction amount calculation unit 53 sets the steering angle difference Δθ1 to the correction amount H1 for the EPS steering angle at the first time when the correction execution condition determination unit 52 determines that the correction execution condition is satisfied, and after the second time. When the conditions for executing the correction of are satisfied, the steering angle difference Δθ2, Δθ3, ... Between the EPS steering angle θEPS and the steering steering angle θSTR is set as the correction amount H2, H3, ... The correction amount Hi (i = 1,2,3, ...) Based on the rudder angle difference Δθi is sent to the correction unit 54.

The correction unit 54 corrects the EPS rudder angle by using the correction amount Hi calculated by the correction amount calculation unit 53. To correct the EPS rudder angle, for example, the correction amount Hi is added to the EPS rudder angle θEPS calculated from the motor rotation angle by the rotation position sensor 24, or the zero point position initially set when the ignition is turned on is corrected by the correction amount Hi and the assist. The correction can be made by resetting based on the reduction ratio r of the transmission mechanism 11.

For example, when correction is performed in pattern A, as shown in FIG. 5, the steering angle difference Δθi between the EPS steering angle and the steering steering angle at the first timing when all the conditions J1, J2, and J3 are satisfied is corrected by a constant amount Hi. As a result, the EPS steering angle is corrected. When correcting the EPS steering angle, it is desirable to limit the change in steering angle by inserting a rate limiter when correcting with the correction amount Hi in order to suppress a sudden change in vehicle behavior. Further, in consideration of the case where the correction amount is not so appropriate, the correction amount Hi may be multiplied by a gain of 1 or less to limit the steering angle after the correction.

Next, the EPS steering angle correction process in the steering control device 50 will be described with reference to the flowchart of FIG.

In this EPS steering angle correction process, first, in the first step S1, it is checked whether or not the ignition switch 25 is turned on. When the ignition switch 25 is OFF, it waits until it is turned ON, and when the ignition switch 25 is ON, the process proceeds to step S2, and the steering angle θSTR detected by the steering angle sensor 22 is set as the EPS steering angle θEPS and rotated. The zero point position of the position sensor 24 is initially set.

Next, the process proceeds to step S3, and it is examined whether or not the steering angle difference Δθi between the steering steering angle θSTR and the EPS steering angle θEPS is equal to or greater than the correction execution threshold value He. As a result, when Δθi <He, it is determined that the correction is not necessary, and this process is terminated. When Δθi ≧ He, it is checked in step S4 whether the number of corrections n has reached the specified number Nset. ..

The specified number of times Nset is the maximum number of times that Δθi <He can be normally set by correcting the EPS rudder angle between the ignition ON and the ignition OFF. When n ≧ Nset, the process proceeds from step S4 to step S5 to determine that an abnormality has occurred, notify another control unit of the occurrence of an abnormality via the communication bus 150, and set the steering angle by the steering angle sensor 22 to the EPS steering angle. The steering control by the electric power steering motor 12 is restricted to ensure safety.

On the other hand, when n <Nset in step S4, the process proceeds from step S4 to step S6 to determine whether or not the EPS steering angle correction execution condition is satisfied. Then, when the correction execution condition is satisfied, the process proceeds from step S6 to step S7. As described above, the correction execution condition is a state in which all the conditions of (J1), (J2), and (J3) are satisfied, or all the conditions of (J1), (J2), and (J3) are satisfied. Is the case where is continued for a certain period of time or longer.

In step S7, the steering angle difference Δθi between the steering steering angle θSTR detected by the steering angle sensor 22 and the EPS steering angle θEPS calculated from the motor rotation angle by the rotation position sensor 24 is determined as the correction amount Hi for the EPS steering angle θEPS. To do. Then, in step S8, the EPS rudder angle θEPS is corrected by the correction amount Hi, and after a predetermined confirmation time has elapsed, the process returns to step S3 described above to check whether the correction is completed.

That is, as shown in FIG. 7, after the ignition is turned on, after a predetermined confirmation time has elapsed as the EPS rudder angle θEPS1 in the first correction (for example, after 1 to 2 seconds have passed since the correction was performed), the steering is steered. It is examined whether or not the steering angle difference Δθ1 between the steering angle θSTR and the EPS steering angle θEPS1 is less than the correction execution threshold value He. Then, when Δθ1 ≧ He, the second correction is performed, and it is checked again whether or not the rudder angle difference Δθ2 is less than the correction execution threshold value He, and when Δθ1 <He, the correction is completed.

As described above, in the present embodiment, the correction amount is the difference between the steering angle detected by the steering angle sensor 22 and the steering angle by the electric power steering motor 12 estimated based on the zero point position of the rotation position sensor 24. It is calculated as Hi, and the steering angle by the electric power steering motor 12 is corrected by this correction amount Hi. As a result, the deviation between the steering angle of the steering wheel and the steering angle of the electric motor can be eliminated. For example, when the follow-up steering control to the preceding vehicle is executed, the target path (traveling locus of the preceding vehicle) is obtained. The controllability of automatic steering by the electric motor can be improved without the own vehicle being offset and unevenly driven.

Next, a second embodiment of the present invention will be described. In the second form, when it is necessary to correct the EPS steering angle with respect to the first form, steering control based on the EPS steering angle such as follow-up steering control to the preceding vehicle is performed until the EPS steering angle correction is experienced. It is prohibited.

Specifically, when the steering angle difference between the steering steering angle and the EPS steering angle needs to be corrected at a predetermined threshold value or more when the ignition is turned on, the steering control is prohibited, and after the EPS steering angle correction is performed, the steering angle is corrected. Allow the implementation of steering control. In the second mode, the EPS rudder angle correction is such that the deviation of the rudder angle is eliminated by one correction when the ignition is turned on, and once the EPS rudder angle correction is performed, the EPS rudder angle correction is performed until the ignition is turned off. Will not be implemented.

Hereinafter, the EPS rudder angle correction process in the second mode will be described. As shown in FIG. 8, the EPS steering angle correction process of the second mode sets the zero position of the rotation position sensor 24 when the ignition switch 25 is turned on in the first steps S11 and S12, as in the first mode. Initial setting is performed, and in step S13, it is checked whether or not the steering angle difference Δθ1 between the steering steering angle θSTR and the EPS steering angle θEPS is equal to or greater than the correction execution threshold He. The steering angle difference Δθ1 here is an average value for several seconds after the ignition is turned on.

If θ1 <He in step S13 and there is no difference in steering angle between the steering angle θSTR and EPS steering angle θEPS, the process jumps from step S13 to step S18 to control steering by the EPS steering angle. Allow and end this process. The permission of steering control is indicated by turning on the steering control execution flag FLG3 (FLG3 = 1), and steering control by the EPS steering angle is started.

That is, as shown in FIG. 9, when the steering angle difference Δθ1 between the steering steering angle and the EPS steering angle is less than the correction execution threshold He after the system diagnosis is permitted when the ignition is turned on, the steering angle difference Δθ1 of Ts for a certain period of time Calculate the average value. Then, when this average value is less than the correction execution threshold value He, it is assumed that the correction is not necessary, and the steering control execution flag FLG3 is turned on to allow the steering control by the EPS steering angle.

As will be described later, when the steering angle difference Δθ1 between the steering angle and the EPS steering angle is equal to or greater than the correction execution threshold value He, the steering angle difference flag FLG11 indicating an instantaneous steering angle deviation is turned ON (FLG11 = 1). Rudder. Further, when the average value of the steering angle difference Δθ1 of Ts for a certain period of time is equal to or greater than the correction execution threshold value He, the steering angle difference flag FLG12 indicating the average steering angle deviation is turned ON (FLG12 = 1). FIG. 9 shows a state in which both the steering angle difference flags FLG11 and FLG12 are 0.

After the steering control execution flag FLG3 is turned on, the steering angle difference Δθ1 is close to the correction execution threshold value He, and even if the instantaneous steering angle difference flag FLG11 fluctuates repeatedly ON and OFF due to the steering operation, the ignition is turned off. Until, the steering control execution flag FLG3 is held in the ON state. Then, while the steering control execution flag FLG3 is ON, the correction execution flag FLG2 indicating whether or not the correction execution conditions according to the conditions (J1), (J2), and (J3) described in the first embodiment are satisfied is OFF. (Correction implementation condition is not satisfied), and EPS steering angle correction is not implemented.

On the other hand, when θ1 ≧ He in step S13 and it is necessary to correct the EPS rudder angle θEPS, the process proceeds from step S13 to step S14, and steering control based on the EPS rudder angle is prohibited (FLG3 = 0). That is, when the steering steering angle θSTR and the EPS steering angle θEPS do not match, the steering control is not executed before the EPS steering angle correction is performed.

After that, the process proceeds from step S14 to step S15, and it is determined whether or not the EPS steering angle correction execution condition is satisfied as in the first embodiment. Then, when the correction execution condition is satisfied, the correction amount Hi for the EPS steering angle θEPS is determined in step S16, the EPS steering angle θEPS is corrected by the correction amount Hi in step S17, and after a predetermined confirmation time elapses, the above-mentioned description is performed. Proceeding to step S18, steering control by the EPS steering angle is permitted (FLG3 = 1).

That is, as shown in FIG. 10, after the ignition switch 25 is turned on, when the steering angle difference Δθ1 between the steering steering angle and the EPS steering angle is equal to or higher than the correction execution threshold He, the steering angle difference flags FLG11 and FLG12 are turned ON. However, until the correction execution condition is satisfied and the correction execution flag FLG2 is turned ON, the steering control execution flag FLG3 remains OFF and steering control by the EPS steering angle is prohibited.

Then, when both the steering angle difference FLG12 and the correction execution flag FLG2 are turned ON and the EPS steering angle correction is performed, the steering control execution flag FLG3 is turned ON, and steering control is executed through the experience of EPS steering angle correction. Rudder. After the steering control execution flag FLG3 is turned ON (after steering control by the EPS rudder angle is permitted), even if the instantaneous steering angle difference flag FLG11 fluctuates repeatedly ON and OFF, until the ignition is turned OFF. , The steering control execution flag FLG3 is held in the ON state. Further, as long as the steering control execution flag FLG3 is ON, the EPS steering angle is not corrected.

Since the EPS steering angle correction is always performed before the steering control is performed and does not affect the vehicle behavior, the limitation using the rate limiter or the gain can be omitted.

In the second form, as in the first form, not only the deviation between the steering steering angle and the EPS steering angle can be eliminated to improve the steering controllability, but also the EPS steering angle is used until the EPS steering angle correction is experienced. Since the steering control is forcibly prohibited, the steering control is not performed without the EPS steering angle matching the steering steering angle, and the occurrence of a defect can be reliably prevented.

1 Electric power steering device 2a Torsion bar 4 Steering wheel 11 Assist transmission mechanism 12 Electric power steering motor 22 Steering angle sensor 23 Torque sensor 24 Rotation position sensor 25 Ignition switch 50 Steering control device 51 Zero point position setting unit 52 Correction execution condition judgment unit 53 Correction amount calculation unit 54 Correction unit Hi Correction amount He Correction execution threshold Δθi Steering angle difference θSTR Steering steering angle θmtr Motor rotation angle

Claims (5)

In a vehicle steering device that can set the steering angle by an electric motor independently of the steering input by the driver.
A zero point position setting unit that sets a zero point position that serves as a reference for the motor rotation angle of the electric motor,
A correction execution condition determination unit that determines whether or not the correction execution condition for correcting the steering angle by the electric motor is satisfied,
When it is determined that the correction execution condition is satisfied, the steering angle difference between the steering angle of the steering wheel and the steering angle by the electric motor estimated based on the zero point position is used as the correction amount for the steering angle by the electric motor. The correction amount calculation unit to be calculated and
When it is determined that the correction execution condition is satisfied, a correction unit for correcting the steering angle by the electric motor with the correction amount is provided .
The correction execution condition determination unit includes at least one of the input torque to the steering wheel, the steering angle difference between the steering angle of the steering wheel and the steering angle of the electric motor, and the steering angle and steering speed of the steering wheel. A vehicle steering device, characterized in that it is determined that the correction execution condition is satisfied when a predetermined condition is satisfied . In a vehicle steering device that can set the steering angle by an electric motor independently of the steering input by the driver.
A zero point position setting unit that sets a zero point position that serves as a reference for the motor rotation angle of the electric motor,
A correction execution condition determination unit that determines whether or not the correction execution condition for correcting the steering angle by the electric motor is satisfied,
When it is determined that the correction execution condition is satisfied, the steering angle difference between the steering angle of the steering wheel and the steering angle by the electric motor estimated based on the zero point position is used as the correction amount for the steering angle by the electric motor. The correction amount calculation unit to be calculated and
When it is determined that the correction execution condition is satisfied, the correction unit that corrects the steering angle by the electric motor with the correction amount
With
Wherein when correction of the steering angle by the electric motor, the correction amount by vehicles of the steering device you characterized in that a limit on the steering angle change. In a vehicle steering device that can set the steering angle by an electric motor independently of the steering input by the driver.
A zero point position setting unit that sets a zero point position that serves as a reference for the motor rotation angle of the electric motor,
A correction execution condition determination unit that determines whether or not the correction execution condition for correcting the steering angle by the electric motor is satisfied,
When it is determined that the correction execution condition is satisfied, the steering angle difference between the steering angle of the steering wheel and the steering angle by the electric motor estimated based on the zero point position is used as the correction amount for the steering angle by the electric motor. The correction amount calculation unit to be calculated and
When it is determined that the correction execution condition is satisfied, the correction unit that corrects the steering angle by the electric motor with the correction amount
With
Wherein when correction of the steering angle by the electric motor, the correction amount by the corrected steering angle vehicles steering apparatus you and limits the. Claims 1 to 1 , wherein when the steering angle difference between the steering angle of the steering wheel and the steering angle by the electric motor is equal to or greater than the correction execution threshold value, the steering angle is corrected by the electric motor a plurality of times. The vehicle steering device according to any one of 3. The vehicle according to any one of claims 1 to 4 , wherein the zero point position setting unit sets the zero point position by using the steering angle of the steering wheel as the steering angle by the electric motor . Steering device.

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