JP2014051128A - Steering unit and steering controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steering unit and steering controller capable of appropriately controlling steering.SOLUTION: A steering unit 1 includes: a steering member 4; an actuator 8; a detector 9 that detects a steering manipulation physical quantity relevant to a steering manipulation; and a steering controller 10 that can implement control to adjust a torque, which is generated by the actuator 8, on the basis of the steering manipulation physical quantity detected by the detector 9. The steering controller 10 can conduct friction control under which the actuator 8 is controlled based on a friction control quantity that should be applied to the steering member 4 according to the steering manipulation physical quantity detected by the detector 9, and conducts the friction control on the basis of a lower limit of the friction control quantity depending on a zero-point deviation of an output of the detector 9. Therefore, the steering unit 1 exhibits the effect that the steering unit can appropriately control steering.

Description

  The present invention relates to a steering device and a steering control device.

  As a conventional steering device and steering control device mounted on a vehicle, for example, Patent Literature 1 discloses a steering control device. The steering control device sets a friction torque value to be applied to the steering based on information representing the vehicle state, sets a target steering angle based on the friction torque value, and sets the target steering angle and the steering angle. An additional friction torque value is set based on the deviation, and the friction torque applied to the steering by the actuator is controlled based on the additional friction torque value.

JP 2009-126244 A

  By the way, the steering control device described in Patent Document 1 described above is controlled in a manner capable of reducing the steering force reduction / stability improvement at the time of steering holding and suppressing the vehicle flow with the above configuration. Although friction torque is applied, there is room for improvement in consideration of, for example, variation in performance of various sensors, deterioration over time, and environmental changes.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a steering device and a steering control device capable of appropriately performing steering control.

  In order to achieve the above object, a steering apparatus according to the present invention includes a steering member that is provided in a vehicle and that can be rotated, an actuator that generates a torque that assists the steering operation on the steering member, and steering related to the steering operation. A steering device for detecting an operation physical quantity; and a steering control device capable of executing a control for adjusting a torque generated by the actuator based on the steering operation physical quantity detected by the detection device. Is capable of executing friction control for controlling the actuator based on a friction control amount to be applied to the steering member in accordance with the steering operation physical quantity detected by the detection device, and a zero point of the output of the detection device The friction control is performed based on a lower limit value of the friction control amount corresponding to the deviation.

  In the steering device, the lower limit value of the friction control amount corresponds to a control amount required to cancel the control amount generated by the actuator due to a zero point deviation of the output of the detection device. It can be.

  In the steering device, the steering control device may change a lower limit value of the friction control amount based on a vehicle speed of the vehicle.

  In the steering apparatus, the detection apparatus includes a torque sensor that detects a steering torque as the steering operation physical quantity, and a steering angle sensor that detects a steering angle as the steering operation physical quantity, and a lower limit of the friction control quantity. The values are the friction control amount corresponding to the torque zero point deviation required to cancel the control amount generated by the actuator due to the zero point deviation of the output of the torque sensor, and the zero point deviation of the output of the steering angle sensor. This can correspond to the sum of the friction control amount corresponding to the steering angle zero point deviation required to cancel the control amount generated by the actuator due to the above.

  In the steering device, the steering control device may change the friction control amount corresponding to the torque zero point deviation based on the vehicle speed of the vehicle and change the lower limit value of the friction control amount.

  In the steering apparatus, the steering control apparatus changes the friction control amount corresponding to the steering angle zero point deviation based on the vehicle speed of the vehicle, and changes the lower limit value of the friction control amount. it can.

  In the steering device, the steering control device detects a steering torque greater than a torque zero point deviation maximum detected torque that is a maximum steering torque that can be detected due to a zero point deviation of the output of the torque sensor. The lower limit value of the friction control amount can be made smaller than in the case where a steering torque equal to or less than the torque zero point deviation maximum detected torque is detected.

  In the steering device, the steering control device may gradually change a lower limit value of the friction control amount when a steering torque larger than the torque zero point deviation maximum detected torque is detected.

  In the steering device, the steering control device may allow the friction control amount to be lowered to the lower limit value or less when the vehicle is automatically steered.

  In order to achieve the above object, a steering control device according to the present invention relates to a steering member that is provided in a vehicle and that can be rotated, an actuator that generates torque for assisting a steering operation on the steering member, and the steering operation. A steering control device that controls a steering device that includes a detection device that detects a steering operation physical quantity, and that can control a torque generated by the actuator based on the steering operation physical quantity detected by the detection device. The friction control for controlling the actuator based on the friction control amount to be applied to the steering member according to the steering operation physical quantity detected by the detection device can be executed, and the output of the detection device The friction control is performed based on a lower limit value of the friction control amount corresponding to a zero point deviation.

  The steering device and the steering control device according to the present invention have an effect that steering control can be appropriately performed.

FIG. 1 is a schematic configuration diagram illustrating a schematic configuration of a steering apparatus according to an embodiment. FIG. 2 is a block diagram illustrating an example of a schematic configuration of the EPS control ECU according to the embodiment. FIG. 3 is a flowchart for explaining an example of control by the EPS control ECU of the steering apparatus according to the embodiment. FIG. 4 is a time chart for explaining the operation of the steering apparatus according to the embodiment. FIG. 5 is a time chart for explaining the operation of the steering apparatus according to the embodiment. FIG. 6 is a schematic configuration diagram illustrating a schematic configuration of a steering apparatus according to a modification.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

[Embodiment]
FIG. 1 is a schematic configuration diagram illustrating a schematic configuration of a steering apparatus according to an embodiment. FIG. 2 is a block diagram illustrating an example of a schematic configuration of the EPS control ECU according to the embodiment. FIG. 3 is a flowchart for explaining an example of control by the EPS control ECU of the steering apparatus according to the embodiment. 4 and 5 are time charts for explaining the operation of the steering apparatus according to the embodiment. FIG. 6 is a schematic configuration diagram illustrating a schematic configuration of a steering apparatus according to a modification.

  A steering device 1 according to the present embodiment shown in FIG. 1 is a device that is mounted on a vehicle 2 and steers a steered wheel 3 of the vehicle 2. The steering device 1 of the present embodiment is a so-called electric power steering device (EPS) that assists the steering force of the vehicle 2 with the power of an electric motor or the like. The steering device 1 includes an electric motor and the like so that a driver can obtain a steering assist force corresponding to a steering force applied to a steering wheel (hereinafter, abbreviated as “steering” unless otherwise specified) 4 as a steering member. To assist the driver's steering operation (steering operation).

  The steering device 1 according to the present embodiment typically has a small amount of mechanical friction of the steering system with respect to a control amount generated by a zero point deviation of an output of a detection device such as a torque sensor or a steering angle sensor. Therefore, the compensation is made so as not to affect the vehicle flow resistance. Typically, the steering device 1 secures a steering holding force by itself by giving a friction characteristic larger than that to the zero point deviation of the output of the detection device by friction control. In this case, for example, the steering device 1 may change the friction characteristic, in other words, the control amount in the friction control, according to the vehicle speed. In addition, the steering device 1 is, for example, a steering torque region larger than the torque sensor maximum deviation amount (torque zero point deviation maximum detected torque), in other words, a steerable steering region where the steering operation by the driver is performed. You may make it restrict | squeeze the control amount in friction control. Further, the steering device 1 may reduce the control amount in the friction control even when the correction steering is performed by automatic steering such as lane keeping assist.

  Hereinafter, each configuration of the steering device 1 will be described in detail with reference to FIG. As shown in FIG. 1, the steering device 1 includes a steering 4 as a steering member, a steering shaft (hereinafter, abbreviated as “shaft” unless otherwise specified) 5, an R & P gear mechanism ( Hereinafter, it is abbreviated as “gear mechanism” unless otherwise specified.) 6, a pair of left and right tie rods 7, an EPS device 8 as an actuator, a detection device 9, and an EPS control ECU 10 as a steering control device. .

  The steering 4 is a member that can be rotated in the direction around the rotation axis X1 and is provided in the driver's seat of the vehicle. The driver can perform a steering operation (steering operation) by rotating the steering 4 about the rotation axis X1. That is, in the vehicle on which the steering device 1 is mounted, the steering wheel 3 is steered (steered) by the steering 4 being operated by the driver.

  The shaft 5 forms a rotating shaft portion of the steering 4. The shaft 5 has one end connected to the steering 4 and the other end connected to the gear mechanism 6. That is, the steering 4 is connected to the gear mechanism 6 via the shaft 5. The shaft 5 can rotate around the central axis along with the steering 4 as the driver rotates the steering 4. The shaft 5 may be divided into a plurality of members such as an upper shaft, an intermediate shaft, and a lower shaft, for example.

  The gear mechanism 6 mechanically connects the shaft 5 and the pair of tie rods 7. The gear mechanism 6 has, for example, a so-called rack and pinion type gear mechanism, and the rotational movement around the central axis of the shaft 5 corresponds to the left-right direction of the pair of tie rods 7 (typically corresponding to the vehicle width direction of the vehicle 2). ) Convert to linear motion.

  Each of the pair of tie rods 7 has a base end portion connected to the gear mechanism 6 and a tie rod end forming a tip end portion connected to each steered wheel 3 via a knuckle arm. That is, the steering 4 is connected to each steered wheel 3 via the shaft 5, the gear mechanism 6, each tie rod 7, and the like.

  The EPS device 8 assists the steering operation (steering operation) on the steering 4 by the driver, and generates torque for assisting the steering operation. The EPS device 8 outputs a steering assist force (assist torque) that assists the steering force (steering torque) input to the steering 4 by the driver. In other words, the EPS device 8 supports the driver's steering operation by driving the steering wheel 3 of the vehicle 2 with an electric motor or the like. The EPS device 8 assists the driver's steering operation by applying an assist torque to the shaft 5. Here, the assist torque is torque that assists the steering torque corresponding to the steering force input to the steering 4 by the driver.

  The EPS device 8 here has a motor 11 as an electric motor and a speed reducer 12. The EPS device 8 of the present embodiment is a column EPS device in which a motor 11 is provided on a shaft 5 such as an intermediate shaft, that is, a so-called column assist type assist mechanism.

  The motor 11 is a column assist electric motor that generates rotational power (motor torque) when electric power is supplied. For example, the motor 11 generates assist torque as a steering assist force. The motor 11 is connected to the shaft 5 through the speed reducer 12 or the like so as to be able to transmit power, and applies a steering assist force to the shaft 5 through the speed reducer 12 or the like. The speed reducer 12 reduces the rotational power of the motor 11 and transmits it to the shaft 5.

  In the EPS device 8, when the motor 11 is rotationally driven, the rotational power (torque) generated by the motor 11 is transmitted to the shaft 5 via the speed reducer 12, thereby performing steering assist. At this time, the rotational power generated by the motor 11 is decelerated by the speed reducer 12 and the torque is increased and transmitted to the shaft 5. The EPS device 8 is electrically connected to an EPS control ECU 10 described later, and the drive of the motor 11 is controlled.

  The detection device 9 detects a steering operation physical quantity related to the steering operation. The steering operation physical quantity detected by the detection device 9 may include, for example, any one of a steering torque, a steering angle (absolute angle, relative angle), and the like. Here, the detection device 9 includes a torque sensor 13, a steering angle sensor 14, a rotation angle sensor 15, and the like.

  The torque sensor 13 detects steering torque as a steering operation physical quantity. Here, the torque sensor 13 detects torque acting on the shaft 5, in other words, torque generated on the shaft 5. The torque sensor 13 detects, for example, torque that acts on a torsion bar (not shown) that is a torsion member that constitutes a part of the EPS device 8. The steering torque (detected torque) detected by the torque sensor 13 is typically a driver steering torque acting on the shaft 5 according to the steering force input from the driver to the steering 4 or the road surface to the steering wheel 3. This is a torque reflecting a disturbance torque or the like input to the shaft 5 from the steered wheel 3 side via the tie rod end in accordance with a disturbance input or the like. The torque sensor 13 is electrically connected to the EPS control ECU 10 and outputs a detection signal corresponding to the detected steering torque to the EPS control ECU 10. The steering torque detected by the torque sensor 13 can be used, for example, for assist control by the EPS control ECU 10.

  The steering angle sensor 14 detects a steering angle (absolute angle) as a steering operation physical quantity. The steering angle sensor 14 detects a steering angle (steering wheel steering angle) that is a rotation angle of the steering 4. The steering angle sensor 14 is electrically connected to the EPS control ECU 10 and outputs a detection signal corresponding to the detected steering angle to the EPS control ECU 10. The steering angle detected by the steering angle sensor 14 can be used, for example, for steering wheel return control, friction control, and the like by the EPS control ECU 10.

  The rotation angle sensor 15 detects the rotation angle of the rotor shaft of the motor 11. The rotation angle sensor 15 is electrically connected to the EPS control ECU 10 and outputs a detection signal corresponding to the detected rotation angle to the EPS control ECU 10. The rotation angle detected by the rotation angle sensor 15 is used, for example, for current control (output control) to the motor 11 by the EPS control ECU 10. The EPS control ECU 10 can also calculate the steering angle (relative angle) based on the rotation angle detected by the rotation angle sensor 15. The steering angle (relative angle) based on the rotation angle detected by the rotation angle sensor 15 can be used for friction control by the EPS control ECU 10, for example.

  The EPS control ECU 10 controls the driving of the EPS device 8. The EPS control ECU 10 is an electronic circuit mainly composed of a known microcomputer including a CPU, a ROM, a RAM, and an interface. The EPS control ECU 10 is electrically connected to various sensors such as the above-described detection device 9 (torque sensor 13, steering angle sensor 14, rotation angle sensor 15) and the EPS device 8, for example. Here, in addition to the detection device 9 described above, the EPS control ECU 10 is further electrically connected to a vehicle speed sensor 16, a front detection device 17, and the like. The vehicle speed sensor 16 detects a vehicle speed that is the traveling speed of the vehicle 2. The front detection device 17 detects the situation on the front side in the traveling direction of the vehicle 2. The forward detection device 17 is, for example, a millimeter wave radar, a radar using a laser or infrared, a short-range radar such as a UWB (Ultra Wide Band) radar, a sonar using a sound wave or an ultrasonic wave in an audible range, a CCD camera, An image recognition device or the like that detects the situation on the front side in the traveling direction of the vehicle 2 by analyzing image data obtained by imaging the front in the traveling direction of the vehicle 2 with the imaging device of FIG. For example, the front detection device 17 may be configured as a situation on the front side in the traveling direction of the vehicle 2, for example, the presence or absence of a peripheral object (such as an obstacle or a preceding vehicle) on the front side in the traveling direction of the vehicle 2. You may make it detect at least 1 among the relative physical quantity which shows a relative positional relationship, the shape of the road where the vehicle 2 drive | works, a lane, etc.

  The EPS control ECU 10 receives electrical signals (detection signals) corresponding to detection results from various sensors, and outputs drive signals to the EPS device 8 according to the input detection results to control the drive. The EPS control ECU 10 can execute control for adjusting the torque generated by the EPS device 8 based on the steering operation physical quantity detected by the detection device 9. The EPS control ECU 10 is electrically connected to, for example, an ECU that controls each part of the vehicle 2 on which the steering device 1 is mounted, and information such as a detection signal, a drive signal, and a control command is mutually transmitted via the ECU. It is good also as a structure which gives / receives, or may be comprised integrally with this ECU.

  The EPS control ECU 10 controls the EPS device 8 based on, for example, the steering torque detected by the torque sensor 13, and adjusts and controls the assist torque generated by the EPS device 8 and acting on the shaft 5. The EPS control ECU 10 adjusts the output torque of the motor 11 by adjusting the motor supply current, which is the supply current to the motor 11, and adjusts the assist torque. Here, the motor supply current is a current having a magnitude that allows the EPS device 8 to generate a predetermined torque required. At this time, the EPS control ECU 10 controls the motor supply current to the motor 11 based on, for example, the rotation angle detected by the rotation angle sensor 15.

  In the steering device 1 configured as described above, the torque generated by the EPS device 8 by the control of the EPS control ECU 10 acts on the shaft 5 together with the steering torque input to the steering 4 from the driver. When the steering force or the steering assist force acts on the tie rod 7 from the shaft 5 through the gear mechanism 6, the steering device 1 responds to the driver steering torque generated by the driver and the torque generated by the EPS device 8. The steering wheel 3 is steered by being displaced in the left-right direction by an axial force of a certain magnitude. As a result, the steering device 1 can steer the steered wheels 3 by the steering force input to the steering 4 from the driver and the steering assist force generated by the EPS device 8, thereby the steering by the driver. The operation can be assisted, and the burden on the driver can be reduced during the steering operation.

  And EPS control ECU10 of this embodiment can perform steering wheel return control, friction control, etc. other than the above assist control as control which adjusts the torque which the EPS apparatus 8 generate | occur | produces, for example.

  The EPS control ECU 10 executes assist control using various methods based on the steering torque as the steering operation physical quantity detected by the torque sensor 13. As described above, the assist control is control for assisting (assisting) the steering operation of the steering wheel 4 by the driver. The EPS control ECU 10 basically controls the motor 11 based on the steering torque detected by the torque sensor 13 so that the EPS device 8 generates an assist torque corresponding to the steering torque. More specifically, the EPS control ECU 10 may control the EPS device 8 and adjust the assist torque based on the steering torque detected by the torque sensor 13 and the vehicle speed detected by the vehicle speed sensor 16. The EPS control ECU 10 calculates a basic target assist torque as a basic assist control amount in the assist control using a control map or the like based on the steering torque and the vehicle speed, and controls the EPS device 8 based on the calculated target assist torque. . In this control map, a correlation between a steering torque, a vehicle speed, and a target assist torque (basic assist control amount) that is a basis for assisting a steering operation with respect to the steering 4 is defined in advance. For example, the EPS control ECU 10 relatively increases the assist torque as the steering torque detected by the torque sensor 13 increases, and relatively decreases the assist torque as the vehicle speed detected by the vehicle speed sensor 16 increases. You may do it.

  Further, the EPS control ECU 10 executes the steering wheel return control using various methods based on the steering angle (absolute angle) as the steering operation physical quantity detected by the steering angle sensor 14. The steering wheel return control is a control for smoothly returning the steering wheel 4 to the neutral position side by applying a steering wheel return torque in the neutral point direction of the steering wheel 4 by the EPS device 8, and more specifically, turning the steering wheel 4 toward the neutral position side. This control assists the returning operation. Here, the neutral position of the steering wheel 4 is a position where the steering angle of the steering wheel 4 becomes 0 °. The EPS control ECU 10 basically controls the motor 11 based on the steering angle detected by the steering angle sensor 14 so that the EPS device 8 generates a handle return torque corresponding to the steering angle. More specifically, the EPS control ECU 10 may control the EPS device 8 to adjust the steering wheel return torque based on the steering angle detected by the steering angle sensor 14 and the vehicle speed detected by the vehicle speed sensor 16. . The EPS control ECU 10 calculates a target steering wheel return torque as a steering wheel return control amount in the steering wheel return control using a control map or the like based on the steering angle and the vehicle speed, and controls the EPS device 8 based on the calculated steering wheel return torque. In this control map, the correlation between the steering angle, the vehicle speed, and the target steering wheel return torque (steering wheel return control amount) for smoothly returning the steering wheel 4 to the neutral position is defined in advance. For example, the EPS control ECU 10 relatively increases the steering wheel return torque as the steering angle detected by the steering angle sensor 14 increases, and relatively increases the steering wheel return torque as the vehicle speed detected by the vehicle speed sensor 16 increases. It may be made smaller. Further, for example, the EPS control ECU 10 sets the steering wheel return torque to 0 when the vehicle speed detected by the vehicle speed sensor 16 is equal to or lower than a predetermined speed set in advance (for example, when the vehicle 2 is stopped). May be.

  Further, the EPS control ECU 10 executes friction control using various methods based on the steering angle as the steering operation physical quantity detected by the detection device 9. Here, as the steering angle detected by the detection device 9, either the steering angle (absolute angle) detected by the steering angle sensor 14 or the steering angle (relative angle) corresponding to the rotation angle detected by the rotation angle sensor 15 is used. May be. Friction control is control which gives and compensates for the friction of a steering system by giving the friction torque which simulates elastic friction by EPS device 8 based on the steering angle which detection device 9 detected, for example. . That is, the EPS control ECU 10 determines a friction torque as a friction control amount to be applied to the steering 4 according to the steering angle detected by the detection device 9, and controls the EPS device 8 based on the determined friction torque. Control can be performed. More specifically, the EPS control ECU 10 sets a friction torque to be applied to the steering 4 based on, for example, the steering angle detected by the detection device 9 and the vehicle speed detected by the vehicle speed sensor 16, and based on this The EPS device 8 may be controlled. In this case, for example, the EPS control ECU 10 sets the target steering angle based on the set friction torque, and sets the additional friction torque value based on the deviation between the target steering angle and the actual steering angle. The EPS control ECU 10 controls the EPS device 8 based on the set additional friction torque value, and controls the friction torque (friction control amount) applied to the steering 4 by the EPS device 8.

  Hereinafter, an example of friction control will be described in more detail. The EPS control ECU 10 calculates (sets) a friction torque to be applied to the steering 4 based on the steering angle detected by the detection device 9 and the vehicle speed detected by the vehicle speed sensor 16. The EPS control ECU 10 calculates a target friction torque as a friction control amount in the friction control using a control map or the like based on the steering angle and the vehicle speed. In this control map, a correlation between the steering angle, the vehicle speed, and the target friction torque (friction control amount) to be applied to the steering 4 is defined in advance. In this case, for example, when the steering angle is the same, the EPS control ECU 10 may relatively increase the friction torque when the vehicle speed is higher than when the vehicle speed is low. It is preferable to generate a certain amount of friction torque from the viewpoint of improving straight-running stability and reducing steering stability and improving stability during steering and holding at high speeds and medium speeds. This is because if the friction torque is large, a feeling of friction is given to the driver and the steering feeling is deteriorated. Further, for example, when the vehicle speed is the same or in the same vehicle speed range, the EPS control ECU 10 relatively increases the friction torque when the steering angle is large compared to when the steering angle is small. You may make it enlarge. This is because when the steering angle is large, a large lateral force is more likely to occur because the steered angle of the steerable wheels 3 is larger than when the steering angle is small. This is because a larger friction torque is required from the viewpoint of reducing the steering holding force and improving the stability.

Then, the EPS control ECU 10 sets a target steering angle based on the friction torque. The EPS control ECU 10 calculates the deviation upper limit value using, for example, the friction torque calculated as described above and a preset gain. The EPS control ECU 10 calculates the deviation upper limit value using, for example, the following mathematical formula (1). In Equation (1), “Δ” represents the deviation upper limit value, “Tt” represents the calculated friction torque, and “K” represents the gain. The gain K may be an arbitrary fixed value determined in consideration of the rigidity of the steering system. The gain K is desirably higher than, for example, the torsional rigidity of a portion (generally a torsion bar) considered to have the lowest steering system rigidity. Here, Tt and K are positive values, and the deviation upper limit Δ is a positive value.

Δ = Tt / K (1)

  Then, the EPS control ECU 10 determines the steering angle θ (current cycle value), the calculated deviation upper limit value Δ, the current target steering angle (the initial value may be 0, or the first detected steering angle). It is determined whether or not θt has a relationship of θ> θt + Δ. When θ> θt + Δ, the EPS control ECU 10 changes the target steering angle θt to a new value using the steering angle θ and the deviation upper limit value Δ according to the equation θt = θ−Δ. That is, when the deviation Δθ (= θt−θ) obtained by subtracting the steering angle θ from the target steering angle θt is Δθ <−Δ, the target steering angle θt is changed (updated) to θt = θ−Δ. . In the case of θ ≦ θt + Δ, the EPS control ECU 10 has a relationship in which the steering angle θ (the current cycle value), the calculated deviation upper limit value Δ, and the current target steering angle θt satisfy θ <θt−Δ. It is determined whether or not. When θ <θt−Δ, the EPS control ECU 10 changes the target steering angle θt to a new value using the steering angle θ and the deviation upper limit value Δ according to the equation θt = θ + Δ. That is, when the deviation Δθ (= θt−θ) obtained by subtracting the steering angle θ from the target steering angle θt is Δθ> Δ, the target steering angle θt is changed (updated) to θt = θ + Δ. The EPS control ECU 10 maintains the current target steering angle θt without changing when θ ≧ θt−Δ. That is, when the deviation Δθ (= θt−θ) obtained by subtracting the steering angle θ from the target steering angle θt is −Δ ≦ Δθ ≦ Δ, the target steering angle θt is maintained without being changed.

  The EPS control ECU 10 sets the additional friction torque Tc based on the target steering angle θt. The additional friction torque Tc is, for example, an expression of Tc = K · Δθ using the steering angle θ, the target steering angle θt calculated as described above, and the gain K (= Tt / Δ), that is, It is calculated by the equation Tc = K (θt−θ). The gain K used here is the same as the gain K used in the above-described target steering angle calculation.

  The EPS control ECU 10 controls the EPS device 8 based on the additional friction torque Tc, and controls the friction torque (friction control amount) applied to the steering 4 by the EPS device 8. Accordingly, since the EPS control ECU 10 generates friction torque in a control manner as described above, the EPS control ECU 10 applies friction torque in the optimum magnitude and direction to the steering 4 according to the vehicle state such as the vehicle speed and the steering angle. be able to.

  Here, for example, the EPS control ECU 10 controls the yaw resonance frequency (for example, about 1.0 to 1.5 Hz) of the vehicle with respect to the friction control amount in order to suppress a delay in the output of the holding friction control amount. It is preferable not to apply a low-pass filter or the like. Even in this case, the EPS control ECU 10 may apply, for example, a low-pass filter of several tens Hz or more for the purpose of noise removal to the friction control amount. The EPS control ECU 10 may set the deviation upper limit value Δ to a predetermined fixed value, and instead may set the gain K to a variable value.

  Hereinafter, an example of a schematic configuration of the EPS control ECU 10 for realizing the above control will be described with reference to the block diagram of FIG.

  The EPS control ECU 10 includes a steering feeling realization unit 10a, a vehicle flow suppression unit 10b, an adder 10c, a current calculation unit 10d, and the like in terms of functional concept.

  The steering feeling realization unit 10a includes an assist control unit 10e, a steering wheel return control unit 10f, and an adder 10g.

  The assist control unit 10e calculates a basic assist control amount in the assist control. The assist control unit 10e receives a detection signal corresponding to the steering torque from the torque sensor 13, and receives a detection signal corresponding to the vehicle speed from the vehicle speed sensor 16. Based on the input detection signal, the assist control unit 10e calculates a basic target assist torque as the basic assist control amount as described above, and outputs a current command value signal corresponding to the assist torque to the adder 10g. Output.

  The handle return control unit 10f calculates a handle return control amount in the handle return control. The steering wheel return control unit 10f receives a detection signal corresponding to the steering angle (absolute angle) from the steering angle sensor 14, and receives a detection signal corresponding to the vehicle speed from the vehicle speed sensor 16. Based on the input detection signal, the handle return control unit 10f calculates the target handle return torque as the handle return control amount as described above, and outputs a current command value signal corresponding to the handle return torque to the adder 10g. Output.

  The adder 10g receives a current command value signal corresponding to the assist torque from the assist control unit 10e, and receives a current command value signal corresponding to the handle return torque from the handle return control unit 10f. Based on the input current command value signal, the adder 10g calculates a target steering feeling realization torque (steering feeling realization control amount) obtained by adding the target assist torque and the target steering wheel return torque. A current command value signal corresponding to the actual torque is output to the adder 10c.

  The vehicle flow suppression unit 10b includes a friction control unit 10h that calculates a friction control amount in the friction control. The friction control unit 10h receives a detection signal corresponding to the steering angle from the detection device 9 (the steering angle sensor 14 or the rotation angle sensor 15), and receives a detection signal corresponding to the vehicle speed from the vehicle speed sensor 16. Based on the input detection signal, the friction control unit 10h calculates a target friction torque as a friction control amount (in other words, a vehicle flow suppression control amount) as described above, and calculates the friction torque (additional friction torque). The corresponding current command value signal is output to the adder 10c.

  The adder 10c receives a current command value signal corresponding to the steering feeling realization torque from the adder 10g, and receives a current command value signal corresponding to the friction torque from the friction control unit 10h. The adder 10c calculates a final target torque (final steering control amount) obtained by adding the target steering feeling realization torque and the target friction torque based on the input current command value signal. A current command value signal corresponding to the target torque is output to the current calculation unit 10d.

  The current calculation unit 10d receives a current command value signal corresponding to the final target torque from the adder 10c. The current calculation unit 10d calculates a motor drive duty based on the input detection signal. The current calculation unit 10d calculates the motor drive duty based on the difference between the current indicated by the current command value signal corresponding to the final target torque and the current (detected value) actually supplied to the motor 11 at the present time. Calculate. At this time, the motor drive duty may be determined in consideration of the rotation angle of the motor 11 from the rotation angle sensor 15. Then, the current calculation unit 10d controls the motor 11 of the EPS device 8 according to the motor drive duty calculated and output in this way. Thereby, the EPS control ECU 10 realizes the assist control, the handle returning control, and the friction control as described above.

  Here, the steering device 1 including the EPS device 8 as in the present embodiment has a decrease in the vehicle flow performance due to the influence of the zero point deviation of the output of the torque sensor 13 and the steering angle sensor 14 constituting the detection device 9. There is a fear. The torque sensor 13 and the steering angle sensor 14 constituting the detection device 9 output a reference voltage corresponding to the zero point when the torque acting on the steering 4 is 0 and when the steering 4 is in the neutral position. Is set to However, the torque sensor 13 and the steering angle sensor 14 are when the torque acting on the steering wheel 4 is 0 or when the steering wheel 4 is in the neutral position due to variations in individual performance of the sensors, aging deterioration, environmental changes, and the like. Even in such a case, the reference voltage corresponding to the zero point may not be output. Deviation in such a phenomenon is called zero output deviation.

  On the other hand, the steering device 1 provides, for example, a dead zone within the sensor error range as described above, and does not output torque as a control amount by the EPS device 8 in such a dead zone, or a steering system It is also possible to output only the controlled variable within the range that does not affect the vehicle behavior using the mechanical friction of the above as the holding force. However, in this case, it is difficult to accurately estimate the mechanical friction of the steering system, and it is realistic not only in terms of variations, aging, and environmental changes, but also in consideration of the possibility of partial failure. It is necessary to limit the control amount to much lower than the lowest possible mechanical friction force that can occur. For this reason, in such cases, control such as assist control and steering wheel return control that are output based on the signals from the sensors as described above are greatly limited within the range where zero point deviation can occur. Therefore, there is a possibility that a sufficient control effect cannot be ensured.

  The steering device 1 of the present embodiment secures a holding force for the control amount generated by the zero point deviation of the output of the detection device 9 by itself, so that the mechanical system of the steering system is within the range where the zero point deviation can occur. This makes it possible to set a large control amount that exceeds the friction.

  Specifically, in the friction control, the EPS control ECU 10 of the present embodiment uses a lower limit value of friction torque (friction control amount) (hereinafter referred to as “friction torque lower limit value”) based on the zero point deviation of the output of the detection device 9. The friction control is executed so that the friction torque does not fall below the lower limit value of the friction torque. That is, the EPS control ECU 10 executes the friction control based on the friction torque lower limit value corresponding to the zero point deviation of the output of the detection device 9. Furthermore, the EPS control ECU 10 defines a friction torque lower limit value corresponding to the zero point deviation of the output of the detection device 9 in the friction control, for example, in order to secure the holding force against the vehicle flow that is released by the control itself.

  Here, the friction torque lower limit value (lower limit value of the friction control amount) is the control required to cancel the control amount (torque) generated by the EPS device 8 due to the zero point deviation of the output of the detection device 9. It corresponds to the amount (torque). The lower limit value of the friction torque in this embodiment is set so as to correspond to the sum of the friction control amount corresponding to the torque zero point deviation and the friction control amount corresponding to the steering angle zero point deviation.

  The torque control amount corresponding to the torque zero point deviation corresponds to a control amount required to cancel the control amount generated by the EPS device 8 due to the zero point deviation of the output of the torque sensor 13 constituting the detection device 9. . That is, the torque control amount corresponding to the torque zero point deviation is a torque required to cancel the assist torque generated by the EPS device 8 by the assist control due to the zero point deviation of the output of the torque sensor 13.

  The friction control amount corresponding to the steering angle zero point deviation is the control amount required to cancel the control amount generated by the EPS device 8 due to the zero point deviation of the output of the steering angle sensor 14 constituting the detection device 9. It corresponds to. That is, the friction control amount corresponding to the steering angle zero point deviation is a torque required to cancel the steering wheel return torque generated by the EPS device 8 by the steering wheel return control due to the zero point deviation of the output of the steering angle sensor 14. is there.

  The torque control amount corresponding to torque zero point deviation and the friction control amount corresponding to steering angle zero point deviation specify the maximum control amount that can be generated due to the zero point deviation of each output in advance based on, for example, actual vehicle evaluation or the like. In addition, it may be stored in the storage unit as a fixed value according to the maximum control amount that can be generated due to this zero point shift. In other words, the lower limit value of the friction torque is determined, for example, by specifying the friction control amount corresponding to the torque zero point deviation and the friction control amount corresponding to the steering angle zero point deviation based on the actual vehicle evaluation or the like, and stored in advance in the storage unit as a fixed value based on this You just have to.

  The friction control unit 10h of the EPS control ECU 10 performs the friction control using the friction torque lower limit value defined as described above. The friction control unit 10h sets the friction torque so that the friction torque actually applied by the friction control does not become the friction torque lower limit value or less, and executes the friction control.

  In this case, for example, as shown in the flowchart of FIG. 3, the friction control unit 10 h first detects the steering angle detected by the detection device 9 (the steering angle sensor 14 or the rotation angle sensor 15) and the vehicle speed sensor 16. Based on the detected vehicle speed, a target friction torque as a friction control amount is calculated (step ST1).

  Then, the friction control unit 10h performs guard processing on the target friction torque calculated in step ST1 with a friction torque lower limit value set in accordance with the zero point deviation (step ST2), and performs the subsequent calculation. Do. Thereby, the friction control part 10h can restrict | limit so that the friction torque actually provided by friction control may not become below this friction torque lower limit.

  As a result, the EPS control ECU 10, for example, does not cause the friction torque applied by the friction control to be equal to or lower than the friction torque lower limit value corresponding to the zero point deviation of the output of the detection device 9 regardless of the setting of the gain K or the like described above. Can be limited. Thereby, unlike the mechanical configuration, the EPS control ECU 10 can easily realize the lower limit compensation of the friction torque by the friction control because the friction control itself does not deteriorate due to aging or environmental changes. be able to.

  Therefore, the steering device 1 is larger than the control amount generated by the zero point shift, regardless of the mechanical friction of the steering system, with respect to the control amount generated by the zero point shift of the output of the detection device 9. The friction characteristic can be imparted in a controllable manner by a friction torque by friction control. Thereby, the steering apparatus 1 can ensure the steering holding force with respect to the zero point shift by itself. As a result, the steering device 1 can properly perform steering control regardless of variations in performance of various sensors, aging deterioration, environmental changes, and the like. For example, by controlling the EPS device 8, the vehicle flow resistance performance can be improved. Compensation can be made so as not to decrease.

  Next, an example of the operation of the steering device 1 will be described with reference to the time charts of FIGS.

  In FIG. 4, the horizontal axis is the time axis, and the vertical axis is the steering torque, the control amount, and the steering angle. FIG. 4 illustrates, as an example, a case where a zero point shift due to temperature drift occurs in the torque sensor 13 due to an environmental change.

  As shown in FIG. 4, in the steering device 1, when a zero point deviation due to a temperature drift occurs in the torque sensor 13 at time t11, a zero point deviation occurs in the steering torque detected by the torque sensor 13 (solid line in FIG. 4). L11). Then, the steering device 1 outputs the basic assist control amount by the assist control according to the zero point deviation in accordance with the change of the steering torque detected by the torque sensor 13 (see the solid line L12 in FIG. 4). As a result, the steering device 1 causes the EPS device 8 to generate assist torque in accordance with the zero point deviation of the output of the torque sensor 13.

  Then, when the assist torque generated by the EPS device 8 overcomes the actual mechanical friction torque of the steering system at time t12, the steering angle of the steering device 1 changes (see the solid line L13 in FIG. 4). . When the steering angle of the steering 4 changes, the steering device 1 starts friction control in accordance with the change of the steering angle, and outputs a friction control amount by the friction control (see a solid line L14 in FIG. 4). Then, immediately after that, the steering device 1 holds the friction control amount by the friction control at the time t13 above the friction torque lower limit value. As a result, when the steering apparatus 1 finally reaches a predetermined steering angle, the basic assist control amount (target assist torque) and the friction control amount (target friction torque) are balanced, and more Accordingly, the steering angle of the steering 4 is not changed, and thereby, it is possible to secure the steering holding force against the zero point deviation. At this time, the current command value for the motor 11 is 0A. On the other hand, in the steering device according to the comparative example in which the friction torque lower limit value corresponding to the zero point deviation is not set in the friction control amount by the friction control, the steering angle of the steering 4 continues to increase until the axial force rises. (See the dotted line L15 in FIG. 4). As described above, the steering device 1 limits the amount of change in the steering angle, for example, to a control amount generated due to the zero point deviation of the sensor so as not to affect the vehicle behavior and to make the driver feel no difference between the left and right. That is, the maximum change amount of the steering angle with respect to the control amount generated by the zero point deviation can be compensated to the minimum.

  In FIG. 5, the horizontal axis is a time axis, and the vertical axis is a steering angle and a control amount. FIG. 5 illustrates, as an example, a case where a zero point shift due to a temperature drift occurs in the steering angle sensor 14 due to an environmental change.

  As shown in FIG. 5, in the steering device 1, when a zero point deviation due to a temperature drift occurs in the steering angle sensor 14 at time t <b> 21, a zero point deviation occurs in the steering angle (absolute angle) detected by the steering angle sensor 14. (See dotted line L21 in FIG. 5). Then, the steering device 1 outputs a steering wheel return control amount by the steering wheel return control in accordance with the shift of the zero point in accordance with the change of the steering angle detected by the steering angle sensor 14 (see the solid line L22 in FIG. 5). Since the steering wheel return control is a control for setting the steering angle to 0, if the steering angle zero point itself serving as a reference drifts, it tends to maintain a shifted state. As a result, the steering device 1 causes the EPS device 8 to generate a steering wheel return torque corresponding to the zero point deviation of the output of the steering angle sensor 14.

  The steering device 1 changes the steering angle of the steering wheel 4 when the steering wheel return torque generated by the EPS device 8 at time t22 exceeds the actual mechanical friction torque of the steering system (see the solid line L23 in FIG. 5). ). When the steering angle of the steering 4 changes, the steering device 1 starts friction control in accordance with the change of the steering angle (here, relative angle), and outputs a friction control amount by the friction control (solid line L24 in FIG. 5). reference). Then, immediately after that, the steering device 1 holds the friction control amount by the friction control at the time t23 above the friction torque lower limit value. As a result, when the steering device 1 finally reaches a predetermined steering angle, the steering wheel return control amount (target steering wheel return torque) and the friction control amount (target friction torque) are balanced. As described above, the steering angle of the steering 4 does not change, and thereby, it is possible to secure the steering holding force against the zero point deviation. At this time, the current command value for the motor 11 is 0A. As a result, the steering device 1 according to this embodiment is a steering device according to a comparative example in which the friction torque lower limit value corresponding to the zero point deviation is not set in the friction control amount by the friction control (see the dotted line L25 in FIG. 5). ), The change amount of the steering angle with respect to the control amount generated by the zero point deviation can be suppressed to be much smaller.

  According to the steering apparatus 1 according to the embodiment described above, the steering 4 provided in the vehicle 2 and capable of rotating operation, the EPS apparatus 8 that generates torque for assisting the steering operation with respect to the steering 4, and the steering related to the steering operation. A detection device 9 that detects an operation physical quantity and an EPS control ECU 10 that can execute control for adjusting torque generated by the EPS device 8 based on the steering operation physical quantity detected by the detection device 9 are provided. The EPS control ECU 10 can execute the friction control for controlling the EPS device 8 based on the friction control amount to be applied to the steering 4 according to the steering operation physical quantity detected by the detection device 9. Friction control is executed based on the lower limit value of the friction control amount corresponding to the zero point deviation of the output.

  Therefore, the steering device 1 and the EPS control ECU 10 can limit the friction torque applied by the friction control so that the friction torque does not fall below the lower limit of the friction torque corresponding to the zero point deviation of the output of the detection device 9. As a result, the steering device 1 and the EPS control ECU 10 can appropriately perform steering control regardless of variations in the performance of various sensors, aging deterioration, environmental changes, and the like. For example, by controlling the EPS device 8, Vehicle flow performance can be maintained.

  In the above description, the friction torque lower limit value has been described as a fixed value, but a variable value may be used. For example, as shown in FIG. 6, the EPS control ECU 10 may be configured such that the vehicle flow suppression unit 10 b includes a change unit 10 i.

  The changing unit 10i changes the friction torque lower limit value (the lower limit value of the friction control amount). For example, the changing unit 10i may change the lower limit value of the friction torque (lower limit value of the friction control amount) based on the vehicle speed of the vehicle 2 detected by the vehicle speed sensor 16. Here, the changing unit 10i changes the friction control amount corresponding to the zero torque point deviation or the friction control amount corresponding to the zero steering angle deviation based on the vehicle speed of the vehicle 2 detected by the vehicle speed sensor 16, for example, Change the lower torque limit.

  For example, the change unit 10 i may change the friction torque lower limit value by relatively reducing the torque control amount corresponding to the torque zero point deviation according to the increase in the vehicle speed of the vehicle 2 detected by the vehicle speed sensor 16. In this case, since the basic assist control amount (assist torque) by the assist control becomes relatively small as the vehicle speed increases, the steering device 1 is finally set if the control amount by the zero point deviation of the torque sensor 13 is a constant value. In particular, the torque generated by the EPS device 8 tends to be small. On the other hand, the steering device 1 relatively reduces the torque control amount corresponding to the torque zero point deviation according to the increase in the vehicle speed of the vehicle 2, so that the minimum necessary torque control amount corresponding to the torque zero point deviation corresponding to the vehicle speed is obtained. The friction torque applied by the friction control can be controlled after setting an appropriate lower limit value of the friction torque according to the vehicle speed. As a result, the steering device 1 can appropriately maintain the vehicle flow resistance performance in each vehicle speed range.

  Conversely, the changing unit 10i may change the friction torque lower limit value by relatively increasing the friction control amount corresponding to the zero-point deviation according to the increase in the vehicle speed of the vehicle 2 detected by the vehicle speed sensor 16. Good. In this case, if the steering angle is the same, the amount of movement of the vehicle 2 tends to increase when the vehicle 2 is traveling at a high speed compared to when the vehicle 2 is traveling at a low speed. The amount of deflection tends to increase. On the other hand, the steering device 1 can obtain an appropriate vehicle flow resistance performance corresponding to the vehicle speed by relatively increasing the torque control amount corresponding to the torque zero point deviation as the vehicle speed of the vehicle 2 increases. Thus, the friction torque applied by the friction control can be controlled after setting the friction torque lower limit value. As a result, the steering device 1 allows a decrease in the vehicle flow resistance in the low speed range where there is no practical problem with respect to the zero point deviation of the torque sensor 13, and in the high speed range that is practically required. The vehicle flow resistance can be improved.

  In addition, the steering device 1 determines the friction characteristics in the case where the friction control amount corresponding to the torque zero point deviation is relatively small in accordance with the increase in the vehicle speed of the vehicle 2 detected by the vehicle speed sensor 16, and the vehicle 2 detected by the vehicle speed sensor 16. A friction characteristic in the case where the friction control amount corresponding to the torque zero point deviation is relatively increased can be combined with the increase in the vehicle speed. In this case, for example, the changing unit 10i increases the friction control amount corresponding to the torque zero point deviation in accordance with the increase in the vehicle speed of the vehicle 2 detected by the vehicle speed sensor 16, and relatively decreases after the peak. May be. As a result, the steering device 1 can realize appropriate vehicle flow resistance performance corresponding to each vehicle speed range.

  The changing unit 10i may change the friction torque lower limit value by relatively reducing the steering angle zero point deviation corresponding friction control amount in accordance with the increase in the vehicle speed of the vehicle 2 detected by the vehicle speed sensor 16. . In the steering wheel return control using the steering angle detected by the steering angle sensor 14, the steering wheel return control amount output in the low speed range tends to be relatively large, and the steering wheel return control amount output in the high speed range tends to be relatively small. For this reason, the influence of the zero point shift of the steering angle sensor 14 tends to be relatively small in the high speed range. On the other hand, the steering device 1 obtains an appropriate vehicle flow resistance performance corresponding to the vehicle speed by relatively reducing the friction control amount corresponding to the steering angle zero point deviation in accordance with the increase in the vehicle speed of the vehicle 2. It is possible to control the friction torque applied by the friction control after setting the lower limit of the friction torque so as to be able to. As a result, the steering device 1 allows the vehicle flow performance to be lowered in a high speed range where there is no practical problem with respect to the zero point deviation of the steering angle sensor 14, and in a low speed range that is practically required. It is possible to improve the anti-vehicle flow performance.

  Conversely, the changing unit 10i changes the friction torque lower limit value by relatively increasing the steering angle zero point deviation corresponding friction control amount in accordance with the increase in the vehicle speed of the vehicle 2 detected by the vehicle speed sensor 16. May be. When the vehicle speed detected by the vehicle speed sensor 16 is equal to or lower than a predetermined speed set in advance, for example, when the vehicle 2 is stopped, the steering device 1 does not need to execute the handle return control. The control amount itself may be set to zero. On the other hand, the steering device 1 increases the friction control amount corresponding to the steering angle zero point deviation in accordance with the increase in the vehicle speed of the vehicle 2 so that the vehicle 2 is resistant to the vehicle flow when the vehicle 2 is stopped. The friction torque applied by the friction control can be controlled after ignoring the performance and appropriately setting the lower limit of the friction torque as the vehicle speed increases. As a result, the steering device 1 allows a decrease in vehicle flow resistance in an extremely low speed range including when the steering angle sensor 14 does not perform the steering wheel return control itself even when the steering point sensor 14 is deviated from zero. The vehicle flow resistance can be improved as the vehicle speed gradually increases.

  In addition, the steering device 1 includes a friction characteristic when the friction control amount corresponding to the steering angle zero point deviation is relatively small in accordance with an increase in the vehicle speed of the vehicle 2 detected by the vehicle speed sensor 16, and a vehicle detected by the vehicle speed sensor 16. It is also possible to combine the friction characteristics in the case where the friction control amount corresponding to the steering angle zero point deviation is relatively increased as the vehicle speed 2 increases. In this case, the changing unit 10i increases the friction control amount corresponding to the steering angle zero point deviation relatively with the increase in the vehicle speed of the vehicle 2 detected by the vehicle speed sensor 16, and relatively decreases after the peak. May be. As a result, the steering device 1 can realize appropriate vehicle flow resistance performance corresponding to each vehicle speed range.

  Further, the changing unit 10 i may change the lower limit value of the friction torque based on the steering torque detected by the torque sensor 13. For example, when the torque sensor 13 detects a steering torque that is larger than the torque zero point deviation maximum detected torque, the changing unit 10i compares the friction torque with that when a torque less than the torque zero point deviation maximum detected torque is detected. The lower limit value may be reduced. Here, the torque zero point deviation maximum detected torque is the maximum steering torque (torque sensor maximum deviation amount) that can be detected due to the zero point deviation of the output of the torque sensor 13, and is based on, for example, actual vehicle evaluation or the like. It is set in advance. For example, when the torque sensor 13 detects a steering torque greater than the torque zero point deviation maximum detected torque, the changing unit 10i may set the friction torque lower limit value to zero. As a result, the steering device 1 has a steering torque region in which the steering torque detected by the torque sensor 13 is larger than the torque zero point deviation maximum detected torque, in other words, a steering torque region in which it can be estimated that the steering operation has been performed by the driver. Then, it is possible to reduce the lower limit value of the friction torque, to suppress the lower limit value of the friction torque in the friction control, or not to limit the lower limit value itself. Therefore, the steering device 1 can suppress or not perform the friction control that increases the friction of the steering system in a control manner during steering by the driver that does not affect the flow of the hand-off vehicle. As a result, the steering device 1 can prevent the friction control from affecting the comfortable steering feeling during steering by the driver.

  At this time, when the torque sensor 13 detects a steering torque that is larger than the torque zero point deviation maximum detected torque, the changing unit 10i may gradually decrease the friction torque lower limit value. In this case, the change amount per unit time of the friction torque lower limit value is set to a change amount that does not give the driver a sense of incongruity based on, for example, actual vehicle evaluation. As a result, when it can be estimated that the steering operation is performed by the driver, the steering device 1 suppresses or performs the friction control itself from the state where the lower limit value of the friction torque by the friction control is limited. It is possible to gradually shift to a state where there is not. Therefore, the steering device 1 can smoothly switch the control so as not to give the driver a sense of incongruity.

  Further, the EPS control ECU 10 may allow the friction control amount (friction torque) in the friction control to be lowered to a friction torque lower limit value or less when the vehicle 2 is automatically steered.

  Here, the EPS control ECU 10 of the present embodiment can execute automatic steering control as control for automatically steering the vehicle 2. The EPS control ECU 10 can control the vehicle 2 based on the detection result by the front detection device 17 and execute automatic steering control, for example. The automatic steering control is, for example, a trajectory control that generates a target trajectory based on a detection result by the front detection device 17 and controls the EPS device 8 of the steering device 1 based on the target trajectory. The EPS control ECU 10 is based on, for example, the presence or absence of a peripheral object on the front side in the traveling direction of the vehicle 2 detected by the front detection device 17, the relative physical quantity between the peripheral object and the vehicle 2, the shape of the road on which the vehicle 2 travels, the lane, and the like. Thus, a target trajectory that is a target travel trajectory of the vehicle 2 is generated. The EPS control ECU 10 is, for example, a travel locus (lane keeping assist) that causes the vehicle 2 that is its own vehicle to travel while being maintained in the current lane (lane), and a travel locus that avoids an obstacle on the front side in the traveling direction of the vehicle 2. Then, a target locus of the vehicle 2 is generated according to a traveling locus that causes the vehicle 2 to travel following the preceding vehicle. Then, the EPS control ECU 10 calculates a corrected control amount (corrected steering torque) so that the vehicle 2 travels in the traveling direction and posture corresponding to the generated target locus, and controls the EPS device 8 based on the corrected control amount. To do. As a result, the vehicle 2 can travel along the target locus while being automatically steered by the steering device 1. Note that the EPS control ECU 10 can arbitrarily switch the automatic steering control on and off according to the driver's intention, for example, according to the driver's switching operation via the changeover switch. Absent.

  Then, the friction control unit 10h of the EPS control ECU 10 performs friction control when the correction control amount (corrected steering torque) by the automatic steering control as described above is actually output and the vehicle 2 is actually automatically steered. It is allowed to reduce the friction torque (friction control amount) at or below the lower limit of the friction torque. That is, the friction control unit 10h can reduce the friction torque in the friction control when the correction steering is performed by, for example, automatic steering such as lane keeping assist. Even in this case, the friction control unit 10h does not actually output the correction control amount by the automatic steering control, and if the vehicle 2 is not actually automatically steered, the friction control unit 10h The restriction by the torque lower limit value is continued as it is. As a result, the steering device 1 can prevent the automatic steering from being hindered when the vehicle 2 is automatically steered after securing the steering holding force against the zero point shift by the friction control.

  The steering device and the steering control device according to the above-described embodiment of the present invention are not limited to the above-described embodiment, and various modifications can be made within the scope described in the claims.

  In the above description, the steering device is a column assist type column EPS device. However, the present invention is not limited to this and can be applied to any of a pinion assist type and a rack assist type.

  In the above description, the detection device 9 has been described as including the steering angle sensor 14. However, the configuration is not limited thereto, and the detection device 9 may be configured without the steering angle sensor 14. In this case, the EPS control ECU 10 may not perform the handle return control, and the friction torque lower limit value may be the friction control amount corresponding to the torque zero point deviation as it is.

1 Steering device 2 Vehicle 3 Steering wheel 4 Steering (steering member)
8 EPS device (actuator)
9 Detection Device 10 EPS Control ECU (Steering Control Device)
10a Steering feeling realization unit 10b Vehicle flow suppression unit 10c Adder 10d Current calculation unit 10e Assist control unit 10f Handle return control unit 10g Adder 10h Friction control unit 10i Change unit 13 Torque sensor 14 Steering angle sensor 15 Rotation angle sensor 16 Vehicle speed sensor 17 Forward detection device

Claims (10)

A steering member provided in the vehicle and capable of rotating operation;
An actuator for generating torque for assisting a steering operation on the steering member;
A detection device for detecting a steering operation physical quantity related to the steering operation;
A steering control device capable of executing control for adjusting torque generated by the actuator based on the steering operation physical quantity detected by the detection device;
The steering control device is capable of executing friction control for controlling the actuator based on a friction control amount to be applied to the steering member in accordance with the steering operation physical quantity detected by the detection device. The friction control is performed based on a lower limit value of the friction control amount corresponding to the zero point deviation of the output,
Steering device. The lower limit value of the friction control amount corresponds to a control amount required to cancel the control amount generated by the actuator due to a zero point deviation of the output of the detection device.
The steering apparatus according to claim 1. The steering control device changes a lower limit value of the friction control amount based on a vehicle speed of the vehicle;
The steering apparatus according to claim 1 or 2. The detection device includes a torque sensor that detects a steering torque as the steering operation physical quantity, and a steering angle sensor that detects a steering angle as the steering operation physical quantity,
The lower limit value of the friction control amount includes a torque control amount corresponding to a torque zero point deviation required to cancel the control amount generated by the actuator due to a zero point deviation of the output of the torque sensor, and the steering angle sensor. Corresponding to the sum of the steering angle zero point deviation corresponding friction control amount required to cancel the control amount generated by the actuator due to the zero point deviation of the output of
The steering apparatus according to any one of claims 1 to 3. The steering control device changes the friction control amount corresponding to the torque zero point deviation based on a vehicle speed of the vehicle, and changes a lower limit value of the friction control amount;
The steering apparatus according to claim 4. The steering control device changes the friction control amount corresponding to the steering angle zero point deviation based on the vehicle speed of the vehicle, and changes the lower limit value of the friction control amount.
The steering apparatus according to claim 4 or 5. When the steering control device detects a steering torque larger than the torque zero point deviation maximum detected torque, which is the maximum steering torque that can be detected due to the zero point deviation of the output of the torque sensor, the torque zero point deviation maximum detection is detected. The lower limit value of the friction control amount is reduced as compared with the case where a steering torque equal to or lower than the torque is detected.
The steering apparatus according to any one of claims 4 to 6. The steering control device gradually changes a lower limit value of the friction control amount when a steering torque larger than the torque zero point deviation maximum detection torque is detected;
The steering apparatus according to claim 7. The steering control device allows the friction control amount to be lowered to the lower limit value or less when the vehicle is automatically steered;
The steering apparatus according to any one of claims 1 to 8. Controlling a steering device provided with a steering member provided in a vehicle and capable of rotating operation, an actuator for generating torque for assisting steering operation with respect to the steering member, and a detection device for detecting a steering operation physical quantity related to the steering operation; A steering control device capable of executing a control for adjusting a torque generated by the actuator based on the steering operation physical quantity detected by the detection device;
Friction control for controlling the actuator based on the friction control amount to be applied to the steering member can be executed in accordance with the steering operation physical quantity detected by the detection device, and the output of the detection device can be shifted to a zero point. The friction control is executed based on a lower limit value of the corresponding friction control amount,
Steering control device.

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