JP2005255035A - Behavior control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To positively and effectively prevent deflection of a vehicle caused by difference of brake driving force of left and right wheels as compared with conventional one, taking into consideration that responsiveness of steering control is lower than responsiveness of brake force control. <P>SOLUTION: When anti-skid control or traction control is only executed regarding one of the left and right wheels (S40, 50, 70), a behavior control target steering angle Δδct of the front wheel for generating counter yaw moment Mc (=-Mf) for canceling yaw moment Mf by difference of front and rear forces of the left and right wheels is operated (S60, 110, 120). A steering angle of the front wheel is controlled (S130-160) making a value in which the sum of provisional target steering angle δst and a behavior control target steering angle Δδct is subjected to low pass filter processing as a target steering angle δt. Target brake force of left and right opposite wheels is subjected to low pass filter processing by a filter constant in response to the responsiveness of steering by a steering angle variable device 24 (S310, 510) and variation degree of the front and rear forces of the wheel is restricted so as to meet to the responsiveness of steering. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a vehicle behavior control device, and more particularly to a behavior control device that controls the behavior of a vehicle by controlling the steering angle of a steered wheel.

  As one of behavior control devices for vehicles such as automobiles, for example, as described in Patent Document 1 below, a vehicle equipped with a steering device that can steer steering wheels independently of a driver's steering operation. In this case, the behavior control by the steering control that steers the steering wheel by the steering means so that the yaw moment acting on the vehicle is canceled by the braking force difference between the left and right wheels during the anti-skid control, and the braking force difference between the left and right wheels is small. A vehicle behavior control device that performs behavior control by controlling the braking force so that when the behavior control by the steering control is being performed, the behavior control by the braking force control is stopped and the anti-skid control is performed. 2. Description of the Related Art A behavior control device configured to control the braking force of a wheel that is not connected to a maximum braking force is already known.

According to such a behavior control device, for example, when anti-skid control is performed on one of the left and right wheels, the difference in braking force between the left and right wheels becomes large, and the yaw moment caused by the braking force difference also acts on the vehicle. Since the yaw moment is canceled by turning the wheel, the vehicle can be prevented from deflecting and the running stability of the vehicle can be improved, and the braking force of the wheel with the higher friction coefficient on the road surface is the maximum braking force. Therefore, the deceleration of the vehicle can be increased and the braking distance of the vehicle can be shortened.
JP 2002-2474 A

  However, in general, the response of the behavior control by the steering control is lower than the response of the behavior control by the braking force control. Therefore, the yaw moment due to the braking force difference cannot always be effectively canceled by the yaw moment by the steering wheel steering. Therefore, there is a problem that it is impossible to effectively prevent the deflection of the vehicle and to effectively improve the running stability of the vehicle. Further, in order to solve this problem, if it is attempted to increase the responsiveness of the behavior control by the steering control, it is inevitable that the cost is increased due to the increase in size and performance of the steering device.

  In the present invention, when anti-skid control is performed on one of the left and right wheels, the steered wheels are steered and anti-skid control is performed so that the yaw moment acting on the vehicle is canceled by the difference in braking / driving force between the left and right wheels. The present invention has been made in view of the above-described problems in the conventional behavior control device for controlling the braking force of the non-wheeled wheel to the maximum braking force, and the main problem of the present invention is the response of the behavior control by the steering control. By taking into account that the braking performance is lower than the response control of the behavior control by the braking force control, it is possible to effectively prevent the vehicle from being deflected due to the difference in braking / driving force between the left and right wheels as compared with the conventional case. Is to improve reliably and effectively.

  According to the present invention, the main problem described above is according to the configuration of claim 1, that is, according to the steering means that can steer the steered wheels independently of the driver's steering operation, and the driver's acceleration / deceleration operation. Longitudinal force control means for controlling the longitudinal force of each wheel, slip control means for performing slip suppression control by controlling the longitudinal force of the wheel by the longitudinal force control means when the slip of the wheel is excessive, and each wheel Means for estimating the longitudinal force of the vehicle, means for calculating the longitudinal force difference-induced yaw moment acting on the vehicle based on the longitudinal force difference between the left and right wheels, and generating a yaw moment in a direction opposite to the longitudinal force difference-induced yaw moment. Steering wheels are steered by means of computing steering wheel behavior control target rudder angle to reduce yaw moment acting on the vehicle, and steering means so that steering wheel steering angle becomes the behavior control target rudder angle Steering system The slip control means determines whether or not the vehicle is traveling on a traveling road with different friction coefficients on the left and right road surfaces, and the vehicle is traveling on a traveling road with different friction coefficients on the left and right road surfaces. Vehicle behavior control characterized by limiting the degree of change in the longitudinal force of the wheel on the side with the higher friction coefficient of the road surface in accordance with the response of the steering wheel turning by the turning means. Achieved by the device.

  According to the present invention, in order to effectively achieve the main problems described above, in the configuration of claim 1, the longitudinal force control means has a target braking force according to the braking operation of the driver. The slip control means controls the braking force of each wheel, and the slip control means is used to control the target braking force of the wheel having the higher friction coefficient on the road surface according to the response of turning of the steered wheels by the turning means. By performing low-pass filtering with a filter constant, the degree of change in the target braking force of the wheel having the higher friction coefficient on the road surface is limited (configuration according to claim 2).

  According to the present invention, in order to effectively achieve the main problem described above, in the configuration of claim 1 or 2, when the slip control means performs the slip control only on one of the left and right wheels. It is determined that the vehicle is traveling on a road having different friction coefficients on the left and right road surfaces, and a wheel on the opposite side to the wheel performing the slip control is determined to be a wheel having a higher road surface friction coefficient. (Structure of claim 3).

  According to the present invention, in order to effectively achieve the main problems described above, in the configuration of claim 1 or 2, the slip control means has a magnitude of a difference in front-rear force between the left and right wheels that exceeds a reference value. When the vehicle is, it is determined that the vehicle is traveling on a road where the left and right road surfaces have different friction coefficients, and the wheel having the higher road surface friction coefficient is determined based on the direction and magnitude of the longitudinal force of the left and right wheels. (Structure of claim 4).

  According to the present invention, in order to effectively achieve the main problems described above, in the configuration of claims 1 to 4, the steering control means sets the behavior control target steering angle to the steering means. Low-pass filter processing is performed with a filter constant for steering angle control corresponding to the steering wheel steering response, and the steering means steers the steering wheel so that the steering angle of the steering wheel becomes the behavior control target steering angle after the low-pass filter processing. It is comprised so that a wheel may be steered (structure of Claim 5).

  According to the configuration of the first aspect, the longitudinal force of each wheel is estimated, the longitudinal force difference-induced yaw moment acting on the vehicle is calculated from the longitudinal force difference between the left and right wheels, and the direction opposite to the longitudinal force difference-induced yaw moment is calculated. The steering wheel behavior control target rudder angle for reducing the yaw moment acting on the vehicle by generating the yaw moment is calculated, and the steered means steers the steered wheel so that the rudder angle of the steered wheel becomes the behavior control target rudder angle. Is turned, and it is determined that the vehicle is traveling on a road with different friction coefficients on the left and right road surfaces, the degree of change in the longitudinal force of the wheel on the side with the higher friction coefficient on the road surface is the steering wheel by the steering means. Therefore, the yaw moment due to the difference in the longitudinal force is prevented from increasing suddenly, so that the yaw moment due to the difference in the longitudinal force is not delayed by the yaw moment due to the steering of the steered wheels. The reliably and effectively cancel, it is possible to reliably and effectively reduce the yaw moment acting on the vehicle.

  Further, according to the configuration of the second aspect, the braking force of each wheel is controlled so that the target braking force according to the braking operation of the driver is obtained, and the target braking force of the wheel having a higher road friction coefficient is steered. Since the low-pass filter processing is performed with the filter constant for braking force control according to the response of the steering wheel to the steered wheel, the degree of change in the target braking force of the wheel having the higher road friction coefficient is limited. The degree of change in the longitudinal force of the wheel on the side having the higher friction coefficient of the road surface can be reliably and effectively limited.

  According to the third aspect of the present invention, when slip control is performed on only one of the left and right wheels, it is determined that the vehicle is traveling on a traveling road having different friction coefficients on the left and right road surfaces, and slip control is performed. Since the wheel on the opposite side to the wheel is determined to be the wheel with the higher friction coefficient on the road surface, the wheel with the higher friction coefficient on the road surface can be reliably determined, thereby increasing the friction coefficient of the road surface. The degree of change in the longitudinal force of the wheel on the side can be reliably and effectively limited.

  According to the configuration of claim 4, it is determined that when the magnitude of the difference in the longitudinal force between the left and right wheels is equal to or greater than a reference value, the vehicle is determined to be traveling on a road having different friction coefficients between the left and right road surfaces. Since the wheel with the higher friction coefficient on the road surface is determined based on the direction and magnitude of the front-rear force of the wheel, the wheel with the higher friction coefficient on the road surface can be determined with certainty. It is possible to reliably and effectively limit the degree of change in the longitudinal force of the wheel on the higher side.

  According to the fifth aspect of the present invention, the behavior control target rudder angle is low-pass filtered with the rudder angle control filter constant corresponding to the steering wheel turning responsiveness of the steered wheel by the steered means, and the steered wheel steer The steering wheel is steered by the steering means so that the angle becomes the behavior control target rudder angle after the low pass filter processing, so that the behavior control target rudder angle suddenly changes due to a change in the friction coefficient of the road surface, etc. Thus, the steering angle of the steered wheel can be controlled to the behavior control target rudder angle after the low-pass filter processing reliably and effectively without a delay in response.

[Preferred embodiment of problem solving means]
According to one preferable aspect of the present invention, in the configuration of the first to fifth aspects, the steering means steers the steering wheel relative to the steering operator operated by the driver. The steering wheel is configured to be steered and driven independently of the driver's steering operation (preferred aspect 1).

  According to another preferred aspect of the present invention, in the configuration according to any one of claims 1 to 5, the turning control means is a counter yaw having the same magnitude as the longitudinal force difference-induced yaw moment and having a reverse direction. A behavior control target rudder angle is calculated as a rudder angle for applying a moment to the vehicle (preferred aspect 2).

  According to another preferred aspect of the present invention, in the configuration of the first to fifth aspects, the means for estimating the longitudinal force of each wheel estimates the driving force of each wheel and determines the braking force of each wheel. It is configured to estimate and to estimate the longitudinal force of each wheel as the sum of the driving force and the braking force (preferred aspect 3).

  According to another preferred aspect of the present invention, in the above-described configuration of the first to fifth aspects, the steering control means is configured to determine the provisional target steering angle of the steered wheels based on the driver's steering operation amount and predetermined steering characteristics. When the slip control means is not operating, the steering angle of the steered wheels is controlled by the turning means based on the provisional target steering angle (preferred aspect 4).

  According to another preferred embodiment of the present invention, in the configuration of the first to fifth aspects of the present invention, the vehicle behavior is controlled by controlling the braking / driving force of each wheel when the behavior of the vehicle is deteriorated. The behavior control means by controlling the braking / driving force to stabilize the behavior control means, and the means for calculating the behavior control target rudder angle is configured to calculate the behavior control target rudder angle when the behavior control means is not operating ( Preferred embodiment 5).

  According to another preferred aspect of the present invention, in the configuration of the first to fifth aspects, the vehicle further includes braking / driving force distribution control means for controlling the distribution of braking / driving force of the wheels when the vehicle is turning accelerated / decelerated. And the means for calculating the behavior control target rudder angle is configured to calculate the behavior control target rudder angle when the braking / driving force distribution control means is not operating (preferred aspect 6).

  According to another preferred aspect of the present invention, in the configuration of claim 2, the slip control means reduces the slip by controlling the braking force of the wheel when the slip of the wheel is excessive. Constructed (preferred embodiment 7).

  According to another preferred embodiment of the present invention, in the configuration of the preferred embodiment 7, when the slip of the wheel is excessive, the target braking force for bringing the slip of the wheel into a predetermined range is provided. Is calculated and slip is reduced by controlling the braking force of the wheel to the target braking force (preferred aspect 8).

  According to another preferred aspect of the present invention, in the configuration of claim 2, the filter constant for the target braking force is the target after the low-pass filtering of the braking force of the wheel having the higher friction coefficient on the road surface. When the braking force is controlled, the yaw moment caused by the difference in the longitudinal force acting on the vehicle due to the difference in the longitudinal force between the left and right wheels is generated without the response delay by the steering wheel turning by the steering means. It is comprised so that it may be a value which enables it to make it (preferable aspect 9).

  According to another preferred aspect of the present invention, in the configuration of claim 4, the slip control means is configured such that when the vehicle is braked, the vehicle is in a state where the magnitude of the braking force difference between the left and right wheels is greater than or equal to a reference value. It is determined that the vehicle is traveling on roads having different friction coefficients on the left and right road surfaces, and the wheel having the higher braking force among the left and right wheels is determined to be the wheel having the higher friction coefficient on the road surface (preferably Aspect 10).

  According to another preferred aspect of the present invention, in the configuration of claim 4, when the vehicle is driven, the slip control means is operated when the difference in the driving force difference between the left and right wheels is greater than or equal to a reference value. It is determined that the vehicle is traveling on roads having different friction coefficients on the left and right road surfaces, and the wheel having the higher driving force among the left and right wheels is determined to be the wheel having the higher friction coefficient on the road surface (preferably Aspect 11).

  In general, the vehicle speed is V, the vehicle yaw rate is γ, the vehicle slip angle is β, the front wheel rudder angle is δf, the vehicle weight is M, the vehicle yaw moment of inertia is Iz, and the front wheel cornering power is Is Cpf, the cornering power of the rear wheel is Cpr, the distance in the vehicle front-rear direction between the center of gravity of the vehicle and the front wheel axle is Lf, and the distance in the vehicle front-rear direction between the center of gravity of the vehicle and the rear wheel axle is Lr. , Mf is the yaw moment due to the difference in the longitudinal force between the left and right wheels, γd is the rate of change of the yaw rate γ of the vehicle, βd is the rate of change of the slip angle β of the vehicle, and a11, a12, a21, a22, b1, b2, When c2 is a value represented by the following formulas 2 to 8, the following formula 1 is established.

Further, assuming that the Laplace operator is s, the transfer function H _γδ of the front wheel steering angle δf (s) with respect to the vehicle yaw rate γ (s) and the yaw moment Mf (s ) Transfer function H _γM is expressed by the following equations 9 and 10, respectively.

  Since the following formula 11 is established from the above formulas 9 and 10, the steering angle δf (s) of the front wheel as the steered wheel for canceling the yaw moment Mf (s) due to the difference in the longitudinal force between the left and right wheels is calculated from the following formula 11. It can be seen that the following equation 12 can be obtained.

  Further, from the above equation 12, the δf of the front wheel as a steered wheel for canceling the yaw moment Mf due to the difference between the front and rear force of the left and right wheels can be simply obtained statically by the following equation 13 without considering the transient response. I understand what I can do.

  Therefore, according to another preferred aspect of the present invention, in the configuration of the first to fifth aspects, the means for calculating the behavior control target rudder angle calculates the behavior control target rudder angle according to the equation 12 or 13. (Preferred embodiment 12).

  The present invention will now be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram showing one embodiment of a vehicle behavior control device according to the present invention applied to a semi-steer-by-wire rear wheel drive vehicle equipped with a turning angle varying device functioning as an automatic turning device. is there.

  In FIG. 1, 10FL and 10FR respectively indicate left and right front wheels as driven steering wheels of the vehicle 12, and 10RL and 10RR respectively indicate left and right rear wheels as drive wheels of the vehicle. The left and right front wheels 10FL and 10FR, which are steering wheels, are rotated via a rack bar 18 and tie rods 20L and 20R by a rack-and-pinion type power steering device 16 driven in response to an operation of the steering wheel 14 by a driver. Steered.

  The steering wheel 14 is connected to a pinion shaft 30 of the power steering device 16 via an upper steering shaft 22 as a first steering shaft, a turning angle varying device 24, a lower steering shaft 26 as a second steering shaft, and a universal joint 28. Drive connected. In the illustrated embodiment, the turning angle varying device 24 is connected to the lower end of the upper steering shaft 22 on the housing 24A side, and is connected to the upper end of the lower steering shaft 26 on the rotor 24B side. An electric motor 32 for turning driving is included.

  Thus, the steering angle varying device 24 drives the lower steering shaft 26 to rotate relative to the upper steering shaft 22, so that the ratio of the steering angles of the left and right front wheels 10 FL and 10 FR, which are the steering wheels, with respect to the rotation angle of the steering wheel 14. In other words, it functions as a steering gear ratio variable device that changes the steering gear ratio, and also functions as an automatic steering device that drives the left and right front wheels 10FL and 10FR relative to the steering wheel 14 for the purpose of behavior control. Then, it is controlled by the steering control unit of the electronic control unit 34.

  In particular, the turning angle variable device 24 rotates the lower steering shaft 26 relative to the upper steering shaft 22 by the electric motor 32 so that the steering gear ratio becomes a gear ratio that achieves a predetermined steering characteristic in a normal state. At the time of auxiliary steering driving, the lower steering shaft 26 is actively rotated relative to the upper steering shaft 22 by the electric motor 32, so that the left and right front wheels 10FL and 10FR are automatically turned on without depending on the driver's steering operation. Steer.

  If an abnormality in which the lower steering shaft 26 cannot be driven to rotate relative to the upper steering shaft 22 occurs in the turning angle varying device 24, a lock device not shown in FIG. The relative rotation of the housing 24A and the rotor 24B is mechanically prevented so that the relative rotation angle of the lower steering shaft 26 with respect to 22 does not change.

  The power steering device 16 may be either a hydraulic power steering device or an electric power steering device. However, the power steering device 16 is generated by the auxiliary steering driving of the front wheels by the steering angle varying device 24 and transmitted to the steering wheel 14. A rack coaxial type electric motor having, for example, an electric motor and a conversion mechanism such as a ball screw type that converts the rotational torque of the electric motor into a reciprocating force of the rack bar 18 so that an auxiliary steering torque for reducing the force torque is generated. A power steering apparatus is preferable.

  The braking force of each wheel is controlled by controlling the pressure Pi (i = fl, fr, rl, rr) in the wheel cylinders 40FL, 40FR, 40RL, 40RR, that is, the braking pressure, by the hydraulic circuit 38 of the braking device 36. It has become so. Although not shown in the drawing, the hydraulic circuit 38 includes an oil reservoir, an oil pump, various valve devices, and the like, and the braking pressure of each wheel cylinder is normally driven in response to the depression operation of the brake pedal 42 by the driver. It is controlled by the master cylinder 44 and individually controlled by the electronic control unit 34 as will be described in detail later if necessary.

  In the illustrated embodiment, the upper steering shaft 22 is provided with a steering angle sensor 50 for detecting the rotation angle of the upper steering shaft as a steering angle θ. The steering angle variable device 24 includes a housing 24A and A rotation angle sensor 52 that detects the relative rotation angle of the rotor 24B as the relative rotation angle θre of the lower steering shaft 26 with respect to the upper steering shaft 22 is provided, and the output of these sensors is supplied to the electronic control unit 34.

  Further, the electronic control unit 34 detects the vehicle longitudinal acceleration Gx detected by the longitudinal acceleration sensor 54, the vehicle lateral acceleration Gy detected by the lateral acceleration sensor 56, and the wheel speed sensors 58FL to 58RR. Further, a signal indicating the wheel speed Vwi (i = fl, fr, rl, rr) of each wheel, a signal indicating the braking pressure Pi of each wheel detected by the pressure sensors 60FL-60RR, and a master cylinder detected by the pressure sensor 62 A signal indicating the pressure Pm, a signal indicating the throttle opening φ and the engine speed Ne, and the like are input from the engine control device 64.

  Although not shown in detail in FIG. 1, the electronic control unit 34 is a steering control unit that controls the steering angle varying device 24, a braking force control unit that controls the braking force of each wheel, and the behavior of the vehicle. Each control unit includes a CPU, a ROM, a RAM, and an input / output port device, which include a microcomputer connected to each other via a bidirectional common bus. Good. Further, the steering angle sensor 50, the rotation angle sensor 52, the lateral acceleration sensor 54, and the yaw rate sensor 56 are respectively set to the steering angle θ, the relative rotation angle θre, and the lateral acceleration when the vehicle is steered, steered, or turned in the left turn direction. Gy and yaw rate γ are detected.

  As will be described later, the electronic control unit 34 normally estimates the vehicle speed V based on the wheel speed Vwi of each wheel, calculates a steering gear ratio Rg for achieving a predetermined steering characteristic based on the vehicle speed V, and steers the driver. The provisional target rudder angle δst is calculated based on the steering angle θ indicating the operation amount and the steering gear ratio Rg, and the steered angle varying device 24 is controlled so that the rudder angle of the left and right front wheels becomes the provisional target rudder angle δst. The left and right front wheels 10FL and 10FR are steered with predetermined steering characteristics in accordance with the steering operation of the person.

  The electronic control unit 34 also obtains a target braking pressure Pti (i = fl, fr) for each wheel by multiplying the master cylinder pressure Pm by a predetermined pressure increase coefficient Ki (i = fl, fr, rl, rr) during normal braking. , Rl, rr), and the control is performed so that the braking pressure Pi becomes the target braking pressure Pti, but the target by the behavior control by the anti-skid control (ABS control) or the traction control (TRC control) or the braking force control described later. When the braking pressure Pti is calculated, control is performed so that the braking pressure of the wheel becomes the target braking pressure Pti of each control.

  The electronic control unit 34 calculates the vehicle body speed Vb and the braking slip amount SBi (i = fl, fr, rl, rr) of each wheel based on the wheel speed Vwi of each wheel in a manner known in the art. When the braking slip amount SBi becomes larger than the reference value for starting the anti-skid control and the anti-skid control start condition is satisfied, the braking slip amount of the wheel falls within the predetermined range until the anti-skid control end condition is satisfied. The anti-skid control is performed by calculating the target braking pressure Pti (i = fl, fr, rl, rr) of the wheel in order to achieve the target braking pressure Pti to be the target braking pressure Pti.

  When the electronic control unit 34 performs anti-skid control for only one of the left and right wheels, the left and right wheels are adjusted by matching the braking force of the wheel on the opposite side to the wheel with the braking force of the wheel on the anti-skid control side. No so-called low select control is performed to prevent the braking force difference between the two from becoming excessive.

  The electronic control unit 34 calculates the vehicle body speed Vb and the acceleration slip amount SAi (i = fl, fr, rl, rr) of each wheel based on the wheel speed Vwi of each wheel in a manner known in the art. When the acceleration slip amount SAi becomes larger than the traction control start reference value and the traction control start condition is satisfied, the acceleration slip amount of the wheel is set within a predetermined range until the traction control end condition is satisfied. Traction control is performed by calculating a target braking pressure Pti (i = fl, fr, rl, rr) of the wheel and controlling the braking pressure Pi to be the target braking pressure Pti.

  When the electronic control unit 34 performs traction control only for one of the left and right wheels, the left and right wheels are controlled by matching the driving force of the wheel on the opposite side to the wheel with the braking force of the wheel on the traction control side. So-called low select control for preventing the power difference from becoming excessive is not performed.

  The electronic control unit 34 also includes a spin state quantity SS indicating the degree of vehicle spin and a drift-out state quantity DS indicating the degree of vehicle drift-out based on the vehicle state quantity such as the lateral acceleration Gy of the vehicle that changes as the vehicle travels. And the target braking pressure Pti (i = fl, fr, rl, rr) for each wheel for stabilizing the behavior of the vehicle based on the spin state amount SS and the drift-out state amount DS is calculated. By controlling the braking pressure Pi to be equal to the target braking pressure Pti, behavior control is performed by controlling the braking force that stabilizes the behavior of the vehicle.

  The above-described behavior control by the anti-skid control, the traction control, and the braking force control itself does not form the gist of the present invention, and these controls are executed in any manner known in the art. Good.

  Further, when the behavior control by the braking force control is not executed and the anti-skid control or the traction control is executed, the electronic control unit 34 calculates the front / rear force Fxi of each wheel by estimation and calculates the front / rear force of the left / right wheel. When the difference ΔFx is greater than or equal to the reference value Fxo (a positive constant), that is, when the vehicle is traveling on a road with different friction coefficients on the left and right road surfaces, and anti-skid control or traction control is being performed on one of the left and right wheels. Then, the yaw moment Mf due to the longitudinal force difference acting on the vehicle is calculated based on the difference in the longitudinal force between the left and right wheels, and the behavior control target rotation of the left and right front wheels for applying to the vehicle a counter yaw moment Mc that cancels the yaw moment due to the longitudinal force difference. The steering angle Δδct is calculated.

  Further, when the electronic control device 34 has the front-rear force difference ΔFx between the left and right wheels equal to or greater than a reference value Fxo (a positive constant) and the anti-skid control or traction control is being executed for one of the left and right wheels, The rate of change in the longitudinal force of the wheel on the opposite side to the wheel being executed is limited in accordance with the response of the steering angle control of the left and right front wheels by the steering angle varying device 24, and thereby the longitudinal force difference-induced yaw moment Mf Prevents the counter yaw moment Mc from following this.

  Next, a vehicle behavior control routine based on the steering angle control of the left and right front wheels achieved by the electronic control unit 34 in the illustrated embodiment will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 2 is started by closing an ignition switch not shown in the figure, and is repeatedly executed at predetermined time intervals.

First, at step 10, a signal indicating the steering angle .theta. Is read, and at step 20, the vehicle speed V is estimated in a manner known in the art based on the wheel speed Vwi of each wheel. The steering gear ratio Rg is calculated from the map corresponding to the graph shown in FIG. 3 based on the vehicle speed V, and the provisional target rudder angle δst of the left and right front wheels for achieving a predetermined steering characteristic according to the following equation 14 is calculated. The
δst = θ / Rg (14)

  The provisional target rudder angle δst is the sum of the rudder angle δw (= θ / Rgo) corresponding to the driver's steering operation and the control turning angle δc for achieving a predetermined steering characteristic. Further, the steering characteristic itself does not form the gist of the present invention, and the steering gear ratio Rg may be calculated in an arbitrary manner known in the art, for example, to improve the transient response of the vehicle to the steering. It may be changed by the steering speed.

  In step 30, it is determined whether or not behavior control based on braking force control, that is, whether spin suppression control or drift-out suppression control is being executed. If an affirmative determination is made, the process proceeds to step 80, and a negative determination is made. When the operation is performed, the process proceeds to step 40.

  In step 40, it is determined whether or not anti-skid control is being performed for any of the wheels. If an affirmative determination is made, the process proceeds to step 60. If a negative determination is made, the process proceeds to step 50. .

  In step 50, it is determined whether or not the traction control is being executed for the left rear wheel or the right rear wheel that is the driving wheel. If a negative determination is made, the process proceeds to step 80, where an affirmative determination is made. If yes, go to Step 60.

In step 60, Ji is the wheel inertia moment, Vwdi is the wheel rotational angular velocity, R is the wheel effective radius, Txi is the wheel braking torque Tbi (negative value) and drive torque Tdi (positive value). ), The longitudinal force (braking / driving force) Fxi (i = fl, fr, rl, rr) of each wheel is calculated according to the following formula 15.
Ji ・ Vwdi ＝ R ・ Fxi + Txi
Fxi = (Ji · Vwdi−Txi) / R (15)

  The rotational angular velocity Vwi of the wheel is calculated as a differential value of the wheel velocity Vwi. The braking torque Tbi is calculated based on a master cylinder pressure Pm detected by a pressure sensor (not shown) and a pressure-braking torque conversion coefficient determined by the specifications of the braking device 36. Further, the drive torque Tdi is calculated based on the throttle opening φ and the engine speed Ne inputted from the engine control device 62, and based on the engine torque Te and a constant determined by the specifications of the drive system. Calculated. Further, the braking torque Tbi and the driving torque Tdi may be directly detected by, for example, a force sensor.

In step 70, the front-rear force difference ΔFx between the left and right wheels is calculated according to the following formula 16 based on the front-rear force Fxi of each wheel, and the absolute value of the front-rear force difference ΔFx between the left and right wheels is a reference value Fxo (a positive constant). ) When the above determination is made and a negative determination is made, the flag Fc is reset to 0 in step 80, and the target steering angle δt of the left and right front wheels is set to the provisional target steering angle in step 90. After setting to δst, the routine proceeds to step 150, and when an affirmative determination is made, the flag Fc is set to 1 at step 100.
ΔFx = (Fxfr + Fxrr) − (Fxfl + Fxrl) (16)

In step 110, the yaw moment Mf due to the longitudinal force difference acting on the vehicle due to the longitudinal force difference between the left and right wheels is calculated according to the following equation 17 based on the longitudinal force difference ΔFx between the left and right wheels with T as the tread of the vehicle. The
Mf = ΔFx · T / 2 (17)

  In step 120, if the counter yaw moment for canceling the longitudinal force difference-induced yaw moment Mf is Mc (= -Mf), the left and right front wheels for applying the counter yaw moment Mc to the vehicle by turning the left and right front wheels. The behavior control target turning angle Δδct is calculated according to the following equation 18 corresponding to the above equation 13. In this case, the behavior control target turning angle Δδct may be calculated according to an equation corresponding to the above equation 12. Further, the cornering power Cpf of the front wheels and the cornering power Cpr of the rear wheels when the behavior control target turning angle Δδct is calculated according to the following equation 18 or the equation corresponding to the above equation 12 are the slip ratio of each wheel at that time. The corrected value is used accordingly.

In step 130, the target rudder angle δt of the left and right front wheels is set to the sum of the provisional target rudder angle δst and the behavior control target turning angle Δδct. In step 140, the current and previous target rudder angles of the left and right front wheels are set. δt is δtai and δtfi, respectively, and the filter constant for steering angle control is Rs (0 <Rs <1), and the low-pass filter processing of the target steering angle δt of the left and right front wheels is performed according to the following equation 19; In this case, the steering angle varying device 24 is controlled so that the steering angle of the left and right front wheels becomes the target steering angle δt after the low-pass filter process, whereby the steering angle of the left and right front wheels is controlled. The filter constant Rs is set to a value that prevents the target rudder angle δt after the low-pass filter processing from including a component higher than the yaw resonance frequency of the vehicle.
δt = Rsδta + (1-Rs) δtf (19)

  Next, the anti-skid control in the illustrated embodiment will be described with reference to the flowchart shown in FIG. Note that the anti-skid control according to the flowchart shown in FIG. 3 is executed for each wheel in the order of the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel, for example.

  First, in step 210, a signal indicating the wheel speed Vwi is read, and in step 220, an estimated vehicle speed Vb is calculated based on the wheel speed Vwi in a manner known in the art, In step 230, the braking slip ratio SBi (i = fl, fr, rl, rr) is obtained by dividing these deviations by the estimated vehicle speed Vwb based on the estimated vehicle speed Vb and the wheel speed Vwi of each wheel. ) Is calculated.

  In step 240, it is determined whether or not the braking force is controlled by the anti-skid control for the wheel. If an affirmative determination is made, the process proceeds to step 260. If a negative determination is made, the process proceeds to step 260. Proceed to 250.

  In step 250, for example, it is determined whether or not the estimated vehicle speed Vb is equal to or higher than the control start reference value Vbs (positive constant) and the braking slip ratio SBi of the wheel is equal to or higher than the reference value SLo (positive constant). Thus, it is determined whether or not the anti-skid control start condition is satisfied for the wheel. If a negative determination is made, the process proceeds to step 280. If an affirmative determination is made, the process proceeds to step 270.

  In step 260, it is determined whether or not the anti-skid control termination condition is satisfied for the wheel, and if an affirmative determination is made, the control routine shown in FIG. When the determination is made, the process proceeds to step 270.

  In step 270, for example, the wheel acceleration calculated as a time differential value of the wheel speed Vwi, the vehicle deceleration Gxb calculated based on the vehicle longitudinal acceleration Gx detected by the longitudinal acceleration sensor 54, and the wheel braking slip ratio. Based on SBi, a target braking pressure Pti (i = fl, fr, rl, rr) for making the braking slip ratio SBi of the wheel within a predetermined range is calculated in a manner known in the art.

  In step 280, it is determined whether or not the flag Fc is 1. When a negative determination is made, the control routine shown in FIG. Proceed to 290.

  In step 290, it is determined whether or not the flag Fc has just changed from 0 to 1. If a negative determination is made, the process proceeds to step 310. If an affirmative determination is made, the process proceeds to step 300. Thus, the previous target braking pressure Ptfi of the wheel is set to the braking pressure Pop of the wheel on the opposite side to the wheel.

In step 310, the target braking pressure Pti (= KiPm) of the wheel based on the master cylinder pressure is set as Ptai, and the filter constant for braking force control by anti-skid control is set as Rb1 (0 <Rb1 <1). By performing low-pass filter processing of the target braking pressure Pti of the wheel according to Equation 20, the target braking pressure Pti after the low-pass filter processing of the wheel is calculated.
Pti = Rb1Ptai + (1-Rb1) Ptfi (20)

  The filter constant Rb1 is set so that the braking force of the wheel on the side where the braking force is not controlled by the anti-skid control, that is, the wheel having the higher friction coefficient of the road surface, becomes the target braking force after the low-pass filter process. , It is possible to generate yaw moments in the opposite direction to the front / rear force difference acting on the vehicle due to the front / rear force difference (braking force difference) between the left and right wheels by turning the steered wheels by the steering means without delay in response. Is set to the value to be

  Next, traction control in the illustrated embodiment will be described with reference to the flowchart shown in FIG. Note that the traction control according to the flowchart shown in FIG. 4 is executed for each of the left and right rear wheels as drive wheels.

  First, at step 410, a signal indicating the wheel speed Vwi is read, and at step 420, an estimated vehicle speed Vb is calculated based on the wheel speed Vwi in a manner known in the art, In step 430, the acceleration slip ratio SAi (i = fl, fr, rl, rr) is obtained by dividing these deviations by the estimated vehicle speed Vb based on the estimated vehicle speed Vb and the wheel speed Vwi of each wheel. ) Is calculated.

  In step 440, it is determined whether or not the braking force is controlled by traction control for the wheel. If an affirmative determination is made, the process proceeds to step 460. If a negative determination is made, step 450 is performed. Proceed to

  In step 450, for example, it is determined whether or not the estimated vehicle speed Vb is equal to or higher than the control start reference value Vbs (positive constant) and the acceleration slip ratio SAi of the wheel is equal to or higher than the reference value SAo (positive constant). Thus, it is determined whether or not the traction control start condition is satisfied for the wheel. If a negative determination is made, the process proceeds to step 480. If an affirmative determination is made, the process proceeds to step 470.

  In step 460, it is determined whether or not the traction control end condition is satisfied for the wheel. When an affirmative determination is made, the control routine shown in FIG. When the operation is performed, the process proceeds to step 470.

  In step 470, for example, the wheel acceleration calculated as a time differential value of the wheel speed Vwi, the vehicle acceleration Gxa calculated based on the vehicle longitudinal acceleration Gx detected by the longitudinal acceleration sensor 54, and the wheel acceleration slip ratio SAi. Based on the above, the target braking pressure Pti (i = fl, fr, rl, rr) for making the acceleration slip ratio SAi of the wheel within a predetermined range is calculated in a manner known in the art.

  In step 480, it is determined whether or not the flag Fc is 1. When a negative determination is made, the control routine shown in FIG. Proceed to 490.

  In step 490, it is determined whether or not the flag Fc has just changed from 0 to 1. If a negative determination is made, the process proceeds to step 510, and if an affirmative determination is made, the process proceeds to step 500. Thus, the previous target braking pressure Ptfi of the wheel is set to the braking pressure Pop of the wheel on the opposite side to the wheel.

In step 510, the target braking pressure Pti (= KiPm = 0) of the wheel based on the master cylinder pressure is set as Ptai, and the filter constant for braking force control by traction control is set as Rb2 (0 <Rb2 <1). The target braking pressure Pti of the wheel is calculated by performing the low-pass filter processing of the target braking pressure Pti of the wheel according to the following equation (21).
Pti = Rb2Ptai + (1-Rb2) Ptfi (21)

  The filter constant Rb2 is controlled so that the braking force of the wheel on the side where the braking force is not controlled by the traction control, that is, the wheel having the higher friction coefficient on the road surface becomes the target braking force after the low-pass filter processing. It is possible to generate a yaw moment in the opposite direction to the yaw moment caused by the difference in the longitudinal force acting on the vehicle due to the difference in the longitudinal force between the left and right wheels (drive force difference) by turning the steered wheels by the steering means without response delay. Set to a value.

  Thus, according to the illustrated embodiment, in step 20, the steering gear ratio Rg for achieving a predetermined steering characteristic is calculated based on the vehicle speed V, and the steering angle .theta. Based on the gear ratio Rg, the provisional target rudder angle δst is calculated. In normal times, in steps 90 and 150, the turning angle variable device 24 is set so that the rudder angle of the left and right front wheels becomes the same target rudder angle δt as the provisional target rudder angle δst. Thus, the left and right front wheels 10FL and 10FR are steered with predetermined steering characteristics in accordance with the driver's steering operation.

  On the other hand, when the behavior control by the braking force control is not executed and the anti-skid control or the traction control is executed, a negative determination is made in step 30 and an affirmative determination is made in step 40 or 50. In step 60, the longitudinal force Fxi of each wheel is calculated by estimation. When the absolute value of the longitudinal force difference ΔFx between the left and right wheels is greater than or equal to the reference value Fxo, an affirmative determination is made in step 70. In step 100, the flag Fc is set to 1, and in step 110, the front-rear force difference-induced yaw moment Mf acting on the vehicle is calculated based on the front-rear force difference between the left and right wheels.

  In step 120, the left and right front wheel behavior control target turning angle Δδct for applying the counter yaw moment Mc for canceling the longitudinal force difference-induced yaw moment Mf to the vehicle is calculated. In step 130, the left and right front wheels are calculated. Is set to the sum of the provisional target steering angle δst and the behavior control target steering angle Δδct. In step 140, the target steering angle δt of the left and right front wheels is subjected to low-pass filter processing. Then, the steering angle varying device 24 is controlled so that the steering angle of the left and right front wheels becomes the target steering angle δt after the low-pass filter process, whereby the steering angle of the left and right front wheels is controlled.

  Therefore, according to the illustrated embodiment, when the behavior control based on the braking force control is not executed and the anti-skid control or the traction control is executed, the counter yaw moment Mf for canceling the yaw moment Mf caused by the longitudinal force difference is canceled. Moment can be applied to the vehicle to effectively prevent the vehicle from deflecting due to the difference in braking / driving force between the left and right wheels, thereby reliably improving the running stability of the vehicle and anti-skid only on one of the left and right wheels. When the control or traction control is executed and the front / rear force difference ΔFx between the left and right wheels is large, the target braking pressure based on the master cylinder pressure of the wheel on the opposite side to the wheel on which the anti-skid control or traction control is executed Since Pti is subjected to low-pass filter processing, the degree of change in braking force of the wheel is reduced. Yaw moment Mf to be able to effectively and reliably canceled without a delay in response by the counter yaw moment due to the left and right front wheels steered.

  FIG. 6 shows an example of the frequency response characteristic of the transfer function of the steering angle δf (s) of the left and right front wheels with respect to the following expression 22 corresponding to the above expression 12, that is, the front-rear force difference-induced yaw moment Mf (s). From FIG. 6, in order to generate a counter yaw moment that effectively cancels the front-rear force difference yaw moment Mf (s) by turning the left and right front wheels, the response of the steering system of the left and right front wheels is the response of the braking system. It turns out that it must be equivalent to sex.

  According to the illustrated embodiment, the filter constant Rb1 is set so that the braking force of the wheel on which the braking force is not controlled by the anti-skid control, that is, the wheel having the higher friction coefficient on the road surface is the target braking force after the low-pass filter processing. When controlled, the yaw moment in the direction opposite to the front / rear force difference acting on the vehicle due to the front / rear force difference (braking force difference) between the left and right wheels is delayed by the steering wheel turning by the steering means. The filter constant Rb2 is set to a value that allows the wheel to be generated without any loss, and the braking force of the wheel on the side where the braking force is not controlled by the traction control, that is, the side with the higher friction coefficient of the road surface, is subjected to the low-pass filter processing. When controlled to achieve the target braking force, the yaw moment in the direction opposite to the yaw moment caused by the difference in the longitudinal force acting on the vehicle due to the difference in the longitudinal force between the left and right wheels (drive force difference) is steered. Because it is set to a value that enables the steering wheel to be generated without response delay by means of steering by means, the counter yaw moment due to the steering of the left and right front wheels is effective for the yaw moment Mf (s) due to the longitudinal force difference without response delay. And surely cancel.

  FIG. 7 shows an example of a Bode diagram of the transfer function of the vehicle yaw rate γ (s) with respect to the above formula 9, that is, the steering angle δf (s) of the left and right front wheels. FIG. 7 shows that the gain varies depending on the vehicle speed, but in the high vehicle speed range, when the frequency becomes 2 Hz or more, the gain decreases and the control becomes oscillating. When controlling the yaw motion of the vehicle by turning the left and right front wheels, increasing the steering frequency of the left and right front wheels not only reduces the control effect, but also increases the size and performance of the turning angle varying device 24. The accompanying increase in cost is not avoided, and furthermore, the reaction force that changes suddenly by turning the left and right front wheels by the turning angle varying device 24 is transmitted to the steering wheel 14 and the driver feels strange.

  According to the illustrated embodiment, the anti-skid control or the traction control is executed for only one of the left and right wheels, and when the magnitude of the front / rear force difference ΔFx between the left and right wheels is large, The left and right front wheel behavior control target turning angle Δδct for applying the counter yaw moment Mc to the vehicle is calculated. In step 130, the target steering angle δt of the left and right front wheels is set to the provisional target steering angle δst and the behavior control target turning angle. In step 140, a low-pass filter process is performed on the target steering angle δt of the left and right front wheels, and in step 150, the steering angle of the left and right front wheels becomes the target steering angle δt after the low-pass filter process. Since the turning angle varying device 24 is controlled as described above, it is possible to reliably prevent the target rudder angle δt from containing a high-frequency component. It is possible to reliably avoid high cost associated with high performance, a reaction force which changes rapidly can the driver is transmitted to the steering wheel 14 is reliably avoided to remember a sense of incongruity.

  Further, according to the illustrated embodiment, when the behavior control by the control of the braking force is being executed, an affirmative determination is made in step 30 and steps 40 to 140 are not executed, so that the behavior of the vehicle is stabilized. Therefore, in a situation where the braking force of each wheel is actively controlled, an unnecessary front / rear force difference-induced yaw moment Mf is calculated based on the front / rear force difference between the left and right wheels by behavior control, and the left and right front wheels 10FL and It is possible to reliably prevent the 10FR from being turned unnecessarily and the resulting stabilization of the vehicle behavior from being hindered.

  Further, according to the illustrated embodiment, it is determined that the anti-skid control or the traction control is executed in step 40 or 50, respectively. In step 70, the absolute value of the front-rear force difference ΔFx between the left and right wheels is the reference value. Since steps 100 to 140 are executed when it is determined that the vehicle is greater than or equal to Fxo, there is a possibility that unnecessary counter yaw moment may be applied to the vehicle as compared with the case where the determination of steps 40 and 50 is not performed. Can be reduced.

  Further, according to the illustrated embodiment, the steering gear ratio Rg for achieving a predetermined steering characteristic is calculated in step 20, and the steering angle θ and the steering gear ratio Rg indicating the steering operation amount of the driver are calculated. Based on this, the provisional target rudder angle δst is calculated, and the normal rudder difference yaw moment Mf does not act on the vehicle. In normal times, the target rudder angle δt of the left and right front wheels is set to the provisional target rudder angle δst in step 90. A predetermined steering characteristic can be reliably achieved.

  Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art.

  For example, in the above-described embodiment, the turning angle varying device 24 as the turning means does not depend on the driver's steering operation by rotating the lower steering shaft 26 relative to the upper steering shaft 22. The left and right front wheels 10FL and 10FR are automatically steered. However, as long as the steerable means can steer the steered wheels independently of the driver's steering operation, for example, a type that expands and contracts the tie rods 20L and 20R. The steering angle variable device and the steer-by-wire type steering device may be of any configuration known in the art, and the steering means steers the rear wheels as auxiliary steering wheels. It may be.

  In the above embodiment, the counter yaw moment Mc applied to the vehicle to cancel the longitudinal force difference-induced yaw moment is -Mf, that is, the magnitude of the longitudinal force difference-induced yaw moment Mf is the same. Although the yaw moment is the reverse direction, the magnitude of the counter yaw moment Mc may be smaller than the magnitude of the yaw moment Mf resulting from the longitudinal force difference.

  Further, in the above-described embodiment, even if the anti-skid control or the traction control is executed, when the behavior control by the control of the braking force is executed, the steps 40 to 140 are not executed. In the case of a vehicle in which braking / driving force distribution control for controlling the distribution of braking / driving force is performed at least between the left and right wheels during turning acceleration / deceleration of the vehicle, step 40 is also performed when the braking / driving force distribution control is being executed. It is preferable that ~ 140 is not executed.

  Further, in the above-described embodiment, when the behavior control by the braking force control is executed, the steps 40 to 140 are not executed, but the behavior control by the braking force control or the braking / driving force distribution is performed. When the control is being executed, the counter yaw moment Mc may be corrected so as to be corrected based on the yaw moment generated by the control.

  In the above-described embodiment, the steering gear ratio Rg for achieving a predetermined steering characteristic is calculated based on the vehicle speed V, and provisional based on the steering angle θ indicating the driver's steering operation amount and the steering gear ratio Rg. The target rudder angle δst is calculated, and normally, the rudder angle of the left and right front wheels is controlled to become the provisional target rudder angle δst, but the steering gear ratio Rg is controlled to achieve a predetermined steering characteristic. May be omitted.

  In the above-described embodiment, the behavior control is such that the braking force of each wheel is controlled and the vehicle's behavior is controlled by applying a required yaw moment to the vehicle. It may be performed by controlling the braking force and driving force of the wheels.

  Further, in the above-described embodiment, the vehicle is a rear wheel drive vehicle in which the rear wheels are driven by an engine. However, the present invention may be applied to a front wheel drive vehicle or a four wheel drive vehicle. The present invention may be applied to a vehicle in which driving wheels are driven by corresponding driving devices, such as a motor type vehicle.

  Especially in the case of a vehicle in which the braking / driving force of each wheel can be controlled independently of each other, such as a wheel-in-motor type vehicle, the longitudinal force of each wheel is adjusted so as to achieve the target longitudinal force according to the driver's acceleration / deceleration operation. Is controlled, and the target longitudinal force of the wheel with the higher friction coefficient on the road surface is low-pass filtered with the longitudinal force control filter constant corresponding to the steering wheel steering response by the steering means, It is preferable that the degree of change in the target longitudinal force of the wheel on the side with the higher friction coefficient of the road surface is limited.

It is a schematic block diagram which shows one Example of the vehicle behavior control apparatus by this invention applied to the semi steer-by-wire type rear-wheel drive vehicle provided with the turning angle variable apparatus which functions as an automatic turning apparatus. It is a flowchart which shows the steering angle control routine of the left-right front wheel in an Example. It is a graph which shows the relationship between the vehicle speed V and steering gear ratio Rg. 4 is a flowchart showing an anti-skid control routine in the illustrated embodiment. It is a flowchart which shows the traction control routine in the example of illustration. It is a graph which shows an example of the frequency response characteristic of the transfer function of the steering angle δf (s) of the left and right front wheels with respect to the yaw moment Mf (s) due to the longitudinal force difference. 6 is a graph showing an example of a Bode diagram of a transfer function of a vehicle yaw rate γ (s) with respect to a steering angle Δf (s) of left and right front wheels.

Explanation of symbols

DESCRIPTION OF SYMBOLS 16 Power steering apparatus 14 Steering wheel 24 Steering angle variable apparatus 34 Electronic controller 36 Braking apparatus 44 Master cylinder 50 Steering angle sensor 52 Rotation angle sensor 54 Longitudinal acceleration sensor 56 Lateral acceleration sensor 58FL-58RR Wheel speed sensor 60FL-60RR Pressure sensor 62 Pressure sensor 64 Engine control device

Claims (5)

  The steering means that can steer the steered wheels independently of the driver's steering operation, the longitudinal force control means that controls the longitudinal force of each wheel according to the driver's acceleration / deceleration operation, and the wheel slip is excessive. In some cases, the front / rear force control means controls the front / rear force of the wheel to control slip suppression, the front / rear force of each wheel is estimated, and the left / right front / rear force difference acts on the vehicle. A means for calculating a yaw moment due to the longitudinal force difference, and a steered wheel behavior control target rudder angle for reducing the yaw moment acting on the vehicle by generating a yaw moment in a direction opposite to the yaw moment due to the longitudinal force difference. Means for calculating, and steering control means for steering the steered wheels by the steered means so that the steered angle of the steered wheels becomes the behavior control target steered angle. of When it is determined whether the vehicle is traveling on roads with different friction coefficients, and when the vehicle is determined to be traveling on roads with different friction coefficients on the left and right road surfaces, A vehicle behavior control device characterized in that the degree of change in longitudinal force is limited in accordance with the response of steering of the steered wheels by the steering means.   The front / rear force control means controls the braking force of each wheel so as to obtain a target braking force according to a driver's braking operation, and the slip control means determines the target braking force of a wheel having a higher friction coefficient on the road surface. Low-pass filter processing is performed with a filter constant for braking force control according to the steering response of the steered wheels by the steering means, thereby limiting the degree of change in the target braking force of the wheel having the higher friction coefficient on the road surface. The vehicle behavior control device according to claim 1.   When the slip control means performs the slip control for only one of the left and right wheels, it is determined that the vehicle is traveling on a road having different friction coefficients on the left and right road surfaces, and the left and right wheels are opposite to the wheel performing the slip control. The vehicle behavior control device according to claim 1, wherein the wheel is determined to be a wheel having a higher friction coefficient on the road surface.   The slip control means determines that the vehicle is traveling on a road having different friction coefficients between the left and right road surfaces when the magnitude of the difference between the left and right wheels is greater than or equal to a reference value. The vehicle behavior control apparatus according to claim 1 or 2, wherein a wheel having a higher road surface friction coefficient is determined based on a direction and a size. The steering control means low-pass-filters the behavior control target steering angle with a filter constant for steering angle control according to the response of steering of the steering wheel by the steering means, and the steering angle of the steering wheel is low-pass. The vehicle behavior control device according to any one of claims 1 to 4, wherein a steered wheel is steered by the steering means so as to have a behavior control target rudder angle after filtering.

Images