JP2010132095A - Vehicle control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle control system improving steering feeling of a driver in steering force compensation controlling when a steering control device fails. <P>SOLUTION: The vehicle control system includes the steering control device 2 controlling a steering angle of a vehicle 10 and a driving force control device 3 controlling driving force distribution of wheels 11FR, 11FL. Also, when the steering control device 2 fails, the driving force control device 3 performs driving force distribution control for the right and left wheels 11FR, 11FL, and thereby steering force compensation control is performed. Then, the steering force compensation control is performed based on the relation between steering torque for a steering wheel 21 of the steering control device 2 and a vehicle state quantity. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vehicle control system, and more particularly to a vehicle control system that can improve a driver's steering feeling during steering force compensation control when a steering control device fails.

  Recent vehicle control systems include a steering control device that controls the steering angle of the vehicle, and a driving force control device that controls the distribution of driving force of the wheels. When the steering control device fails, the steering force compensation control is performed by the driving force control device performing the driving force distribution control of the left and right wheels. As a conventional vehicle control system (steering control device) that employs such a configuration, a technique described in Patent Document 1 is known.

JP 2007-161191 A

  Here, when the steering control device fails, the steering force compensation control is preferably performed without deteriorating the steering feeling of the driver.

  Therefore, the present invention has been made in view of the above, and an object of the present invention is to provide a vehicle control system that can improve a driver's steering feeling at the time of steering force compensation control when a steering control device fails.

In order to achieve the above object, a vehicle control system according to the present invention includes a steering control device that controls a steering angle of a vehicle and a driving force control device that controls the distribution of driving force of wheels, and the steering control device is lost. A vehicle control system in which steering force compensation control is performed by the drive force control device performing drive force distribution control of the left and right wheels when falling,
The steering force compensation control is performed based on a relationship between a steering torque of a steering wheel of the steering control device and a vehicle state quantity.

  In this vehicle control system, when the steering control device fails, the steering force compensation control is performed based on the relationship between the steering torque of the steering wheel and the vehicle state quantity (for example, the target yaw rate). In such a configuration, for example, there is an advantage that the steering feeling of the driver is improved as compared with the configuration in which the steering force compensation control is performed based on the relationship between the steering angle of the steering wheel and the target yaw rate when the steering control device fails. is there. That is, since the phase of the steering torque is ahead of the phase of the steering angle, the steering force compensation control suitable for the driver's steering operation is possible, and the driver's steering feeling is improved.

  In the vehicle control system according to the present invention, a target yaw rate corresponding to the steering torque of the steering wheel is used as the vehicle state quantity.

  This vehicle control system has the advantage that the burden of noise filtering on the output value of the vehicle state quantity sensor (yaw rate sensor) is reduced.

  In the vehicle control system according to the present invention, the steering force compensation control is performed when the vehicle speed V and the predetermined threshold value Vth have a relationship of V ≦ Vth.

  In this vehicle control system, since appropriate steering force compensation control is performed during low-speed traveling that requires a large steering angle or a large steering torque, there is an advantage that the steering feeling of the driver is further improved.

  In the vehicle control system according to the present invention, when the steering control device fails, the steering force compensation control is performed based on the relationship between the steering torque of the steering wheel and the vehicle state quantity (for example, the target yaw rate). In such a configuration, for example, there is an advantage that the steering feeling of the driver is improved as compared with the configuration in which the steering force compensation control is performed based on the relationship between the steering angle of the steering wheel and the target yaw rate when the steering control device fails. is there. That is, since the phase of the steering torque is ahead of the phase of the steering angle, the steering force compensation control suitable for the driver's steering operation is possible, and the driver's steering feeling is improved.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Further, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

  FIG. 1 is a configuration diagram showing a steering control device according to an embodiment of the present invention. 2 to 4 are a flowchart (FIG. 2), a control block diagram (FIG. 3), and an explanatory diagram (FIG. 4) showing the operation of the steering control device shown in FIG.

[Vehicle control system]
The vehicle control system 1 includes a steering control device 2, a driving force control device 3, and a control unit 4 (see FIG. 1). This vehicle control system 1 is applied, for example, to an electric vehicle (Electric Vehicle) that drives the front wheels 11FR and 11FL by left and right independent motor generators. In the vehicle control system 1, when the steering control device 2 fails, the driving force control device 3 performs the driving force distribution control of the left and right wheels, thereby performing the steering force compensation control.

  The steering control device 2 is a device that controls the steering angle of the vehicle 10, and includes a steering wheel 21 and a steering actuator 22 (see FIG. 1). The steering wheel 21 is an operation end for giving a steering angle to the left and right front wheels 11FR and 11FL of the vehicle 10, and is operated by a driver. The steering actuator 22 gives an axial displacement to the tie rod 23 to give a steering angle to the front wheels 11FR and 11FL. The steering actuator 22 is connected to the front wheels 11FR and 11FL via a knuckle arm (not shown) and a tie rod 23. In the steering control device 2, when the steering wheel 21 is operated, the control unit 41 drives the steering actuator 22 based on the operation angle. Then, when the steering actuator 22 displaces the tie rod 23, a steering angle is given to the front wheels 11FR and 11FL (steering control).

  The driving force control device 3 is a device that controls the driving force distribution of the left and right wheels 11FR and 11FL of the vehicle 10, and includes a power storage unit 31, a pair of left and right motor generators 32 and 32, and an inverter 33 (FIG. 1). reference). The power storage unit 31 is a DC power source that can be charged and discharged, and includes, for example, a secondary battery such as nickel metal hydride or lithium ion. The motor generator 32 is, for example, a three-phase AC synchronous motor, and is disposed corresponding to the left and right front wheels 11FR and 11FL of the vehicle 10, respectively. Each motor generator 32 is connected to power storage unit 31 via inverter 33. Further, the output shaft of each motor generator 32 is connected to the front wheels 11FR and 11FL of the vehicle 10 via a reduction gear. In the driving force control device 3, the electric power of the power storage unit 31 is supplied to the motor generator 32 via the inverter 33. When the inverter 33 is driven by the control unit 4, the motor generator 32 is driven by the three-phase AC power from the inverter 33, and the power is transmitted to the wheels 11FR and 11FL. At this time, the left and right motor generators 32, 32 are independently driven, thereby controlling the torque distribution of the left and right wheels 11FR, 11FL (driving force distribution control).

  The control unit 4 includes an ECU (Electronic Control Unit) 41 and various sensors 42 to 46 (see FIG. 1). The various sensors 42 to 46 include, for example, a rotation sensor 42 that detects the rotation speed of the motor generator 32, a steering angle sensor 43 that detects the steering angle of the front wheels 11FR and 11FL, and a steering torque sensor that detects the steering torque of the steering wheel 21. 44, a vehicle speed sensor 45 that detects the traveling speed (vehicle speed) V of the vehicle 10, a yaw rate sensor 46 that detects the yaw rate of the vehicle 10, and the like. In the control unit 4, the ECU 41 controls the steering control device 2 and the driving force control device 3 based on the output values of the various sensors 42 to 46. As a result, the above-described steering control and driving force distribution control, steering force compensation control described later, and the like are performed.

  In this embodiment, the steering control device 2 employs a system (steer-by-wire system) in which the steering wheel 21 and the front wheels 11FR and 11FL are mechanically separated. That is, when the steering wheel 21 is operated, the ECU 41 drives the steering actuator 22 based on the output value of the steering torque sensor 44. However, the present invention is not limited to this, and the steering control device 2 may adopt an EPS (Electronic Power Steering) system.

  Further, failure detection means (not shown) of the steering control device 2 is provided. A well-known thing can be employ | adopted for this failure detection means. For example, the failure of the steering control device 2 is detected by comparing the operation angle of the steering wheel 21 with the steering angles of the front wheels 11FR and 11FL and detecting the failure of the steering control device 2.

[Steering force compensation control]
In the vehicle control system 1, steering force compensation control is performed as follows (see FIG. 2). First, when the vehicle travels, the vehicle speed V, the steering torque of the steering wheel 21, the actual yaw rate of the vehicle 10, and the like are acquired (ST1). These are acquired by the ECU 41 as output values of the various sensors 42 to 46 of the control unit 4. Next, it is determined whether or not the steering control device 2 has failed (failure determination step ST2).

  Next, when it is determined in the failure determination step ST2 that the steering control device 2 has failed, it is determined whether or not the vehicle speed V and the predetermined threshold value Vth have a relationship of V ≦ Vth. (Vehicle speed determination step ST3). The threshold value Vth is a threshold value that defines a low-speed traveling time that requires a large steering angle or a large steering torque. The ECU 41 has a map relating to the threshold value Vth.

  Next, when it is determined in the vehicle speed determination step ST3 that the vehicle speed V and the predetermined threshold value Vth have a relationship of V ≦ Vth, steering force compensation control is performed (steering force compensation step ST4) (FIG. 3). In this steering force compensation step ST4, first, the ECU 41 calculates a target yaw rate based on the steering torque acquired in step ST1. At this time, a map that preliminarily defines the relationship between the steering torque and the target yaw rate is used. Next, a deviation (yaw rate deviation) between the target yaw rate and the actual yaw rate of the vehicle 10 is calculated by the feedback controller of the ECU 41. Next, a driving force distribution left-right difference is calculated based on the yaw rate deviation. This driving force distribution left / right difference defines the left / right difference between the torques distributed to the left and right motor generators 32 and 32 in the driving force distribution control by the driving force control device 3. Further, the driving force distribution left / right difference is calculated by the driving force distribution controller of the ECU 41. Then, driving force distribution control is performed based on the calculated driving force distribution left-right difference (ST5).

  For example, when it is determined that the steering control device 2 has failed during the left turn of the vehicle 10 (ST2), the steering force in the left turn direction of the vehicle 10 is compensated (ST4 and ST5). Specifically, the target yaw rate is calculated based on the acquired steering torque in the left turning direction, and the torque of the motor generator 32 of the left front wheel 11FL is calculated based on the deviation between the target yaw rate and the actual yaw rate. The driving force distribution left / right difference is set to be larger than the torque of the motor generator 32. And driving force distribution control is performed based on this driving force distribution left-right difference. As a result, the steering force in the left turning direction of the vehicle 10 is compensated (see FIG. 4).

  On the other hand, when it is not determined in the failure determination step ST2 that the steering control device 2 has failed, and in the vehicle speed determination step ST3, the vehicle speed V and the predetermined threshold value Vth have a relationship of V ≦ Vth. If not, then normal driving force control (ST6) and driving force distribution control (ST5) are performed.

[effect]
As described above, in the vehicle control system 1, when the steering control device 2 fails, the steering force compensation control is performed based on the relationship between the steering torque of the steering wheel 21 and the vehicle state quantity (for example, the target yaw rate). (See FIGS. 2 and 3). In such a configuration, for example, compared to a configuration in which steering force compensation control is performed based on the relationship between the steering angle of the steering wheel and the target yaw rate when the steering control device fails (not shown), the driver's steering feeling is reduced. There is an advantage to improve. That is, since the phase of the steering torque is ahead of the phase of the steering angle, the steering force compensation control suitable for the driver's steering operation is possible, and the driver's steering feeling is improved.

  Also, with such a configuration, for example, there is a problem of an increase in system weight or an increase in size compared to a configuration in which hardware design is performed so that the steering force does not become excessive when the steering control device fails (not shown). Absent. Further, for example, there is no problem that the cost of the system is increased by the backup device as compared with a configuration (not shown) having a steering torque assist backup device.

  In this embodiment, in the steering force compensation control, the target yaw rate corresponding to the steering torque of the steering wheel is used as the vehicle state quantity (see FIG. 3). Such a configuration has an advantage that the burden of noise filtering on the output value of the vehicle state quantity sensor (yaw rate sensor 46) is reduced. However, the present invention is not limited thereto, and for example, the lateral acceleration of the vehicle 10 may be used as the vehicle state quantity.

  In this embodiment, the steering force compensation control is performed when the vehicle speed V and the predetermined threshold value Vth have a relationship of V ≦ Vth (see FIGS. 2 and 3). In such a configuration, appropriate steering force compensation control is performed during low-speed traveling that requires a large steering angle or a large steering torque, so that there is an advantage that the steering feeling of the driver is further improved. Further, in such a configuration, for example, the driver's steering feeling during low-speed driving is reduced as compared with a configuration (not shown) that reduces the backup load by reducing the performance difference between the steering control device failure time and the normal time. improves.

  As described above, the vehicle control system according to the present invention is useful in that the steering feeling of the driver can be improved during the steering force compensation control when the steering control device fails.

It is a block diagram which shows the steering control apparatus concerning the Example of this invention. It is a flowchart which shows the effect | action of the steering control apparatus described in FIG. It is a control block diagram which shows the effect | action of the steering control apparatus described in FIG. It is explanatory drawing which shows the effect | action of the steering control apparatus described in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle control system 2 Steering control apparatus 21 Steering wheel 22 Steering actuator 23 Tie rod 3 Driving force control apparatus 31 Power storage part 32 Motor generator 33 Inverter 4 Control unit 41 Control unit 42 Rotation sensor 43 Steering angle sensor 44 Steering torque sensor 45 Vehicle speed sensor 46 Yaw rate sensor 10 Vehicle 11FR, 11FL Front wheel

Claims (3)

A steering control device that controls the steering angle of the vehicle and a driving force control device that controls the distribution of driving force of the wheels; and when the steering control device fails, the driving force control device drives the left and right wheels. A vehicle control system in which steering force compensation control is performed by performing force distribution control,
The vehicle control system, wherein the steering force compensation control is performed based on a relationship between a steering torque of a steering wheel of the steering control device and a vehicle state quantity.   The vehicle control system according to claim 1, wherein a target yaw rate corresponding to a steering torque of the steering wheel is used as the vehicle state quantity.   The vehicle control system according to claim 1, wherein the steering force compensation control is performed when a vehicle speed V and a predetermined threshold value Vth have a relationship of V ≦ Vth.

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