JP2007196921A - Traveling control device of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively reduce lowering of traveling stability of a vehicle by controlling the steering angle of a wheel to reduce the influence of an abnormality that the front/rear distribution of roll rigidity becomes more to a rear wheel as compared with that at a normal time when the abnormality is generated. <P>SOLUTION: When the abnormality that the front/rear distribution of roll rigidity is close to the rear wheel as compared with that at the normal time is generated in an active stabilizer device 16 or 18 due to lowering of roll rigidity on a front wheel side (S215, 250 and 320), a target steering gear ratio Rg is calculated as a larger value as compared with the case where the abnormality is not generated (S340). Based on the target steering gear ratio Rgt, a target steering angle δft is calculated (S350). By controlling a steering angle variable device 24 so that a steering angle δf of the front wheel may be the target steering angle δft (S360 and 370), a change of a steering characteristic of the vehicle to an oversteer side is suppressed, and turning responsiveness of the vehicle to a steering operation of a driver is lowered. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle travel control device, and more particularly, to a vehicle travel control device including a steering angle variable device capable of controlling the steering angle of a wheel and a roll stiffness control device that variably controls the roll stiffness of the vehicle. Related.

  As one of travel control devices for vehicles such as automobiles, front wheels for variably controlling roll rigidity on the front wheel side and the rear wheel side of the vehicle, respectively, as described in, for example, the following Patent Document 1 filed by the applicant of the present application. In a vehicle equipped with a side and rear wheel side active stabilizer device, when an abnormality occurs in any of the active stabilizer devices, the other active stabilizer device is controlled according to a control rule changed according to the content of the abnormality. A traveling control device is conventionally known.

According to such a travel control device, compared with the case where the control rule is not changed even if an abnormality occurs in any of the active stabilizer devices, the influence of the abnormality of the active stabilizer device on the turning traveling motion of the vehicle is reduced. As a result, it is possible to reduce a decrease in the running stability of the vehicle when turning.
JP 2003-226127 A

  In general, in vehicles equipped with front wheel side and rear wheel side active stabilizer devices, for example, due to an abnormality in the front wheel side or rear wheel side active stabilizer device, the roll rigidity front-rear distribution is closer to the rear wheels than normal. When this occurs, the vehicle steer characteristic changes to the oversteer side as compared to the normal time, so that the running stability of the vehicle during a turn decreases. In particular, when the roll rigidity on the front wheel side decreases, the roll resonance frequency of the vehicle approaches the yaw resonance frequency, so that the running stability of the vehicle tends to decrease.

  However, the conventional travel control device as described above is to control the other active stabilizer device according to the control rule changed according to the content of the abnormality when an abnormality occurs in any of the active stabilizer devices. It is not always possible to effectively reduce the change in the steering characteristics and the decrease in the running stability of the vehicle. In particular, when the roll stiffness on the front wheel side decreases and the roll stiffness on the rear wheel side also decreases, the roll of the vehicle during turning tends to be excessive, and the roll resonance frequency of the vehicle approaches the yaw resonance frequency. Thus, there is a problem that the running stability of the vehicle is likely to be lowered.

  The present invention has been made in view of the above-described problems in the conventional travel control device for a vehicle including front wheel side and rear wheel side active stabilizer devices that variably control the roll rigidity of the front wheel side and the rear wheel side. The main problem of the present invention is to reduce the influence caused by the fact that the front / rear distribution of roll rigidity is closer to the rear wheel when an abnormality occurs where the front / rear distribution of roll rigidity is closer to the rear wheel than when normal. By controlling the rudder angle of the wheels, it is possible to effectively reduce the decrease in running stability of the vehicle.

[Means for Solving the Problems and Effects of the Invention]
According to the present invention, the main problem described above is a vehicle travel control device having a steering angle control means for controlling the steering angle of a wheel and a roll rigidity control means for variably controlling the roll rigidity of the vehicle, When an abnormality occurs in the roll stiffness control means that causes the front and rear distribution of roll stiffness to be closer to the rear wheels, the rudder angle control means causes the wheels to reduce the turning responsiveness of the vehicle to the driver's steering operation. A vehicle travel control device (structure of claim 1), a steering angle control means for controlling the steering angle of a wheel, and a roll stiffness control means for variably controlling the roll rigidity of the vehicle The steering angle control means controls the yaw attenuation of the vehicle when an abnormality occurs in the roll rigidity control means in which the front and rear distribution of the roll rigidity is closer to the rear wheel as compared with the normal time. Increased characteristics It is achieved by the traveling control apparatus for a vehicle characterized by (Configuration of Claim 4) to control the steering angle of the wheel to.

  According to the first aspect of the present invention, when an abnormality occurs in the roll stiffness control means that the front and rear distribution of the roll stiffness is closer to the rear wheel than when it is normal, the turning response of the vehicle to the driver's steering operation is reduced. Since the steering angle of the wheel is controlled so that the front and rear distribution of the roll stiffness is closer to the rear wheel than in the normal state and the steering characteristic of the vehicle changes to the oversteer side compared to the normal state, the steering of the wheel By controlling the angle, the turning responsiveness of the vehicle to the driver's steering operation can be surely reduced, thereby reliably reducing the stability of the vehicle due to the change of the steering characteristic toward the oversteer side. And it can reduce effectively.

  According to the fourth aspect of the present invention, when an abnormality occurs in the roll stiffness control means in which the front and rear distribution of the roll stiffness is closer to the rear wheel than in the normal case, the wheel steering is controlled so that the yaw damping characteristic of the vehicle is increased. Since the angle is controlled, the yaw damping characteristic of the vehicle is increased even if the roll rigidity front-rear distribution is closer to the rear wheel than normal and the vehicle steer characteristic changes to the oversteer side compared to normal. As a result, the fluctuation of the yaw rate of the vehicle accompanying the steering operation of the driver can be quickly attenuated, thereby reliably and effectively reducing the stability of the vehicle due to the change of the steering characteristic toward the oversteer side. Can be reduced.

  According to the present invention, the steering angle control means controls the steering transmission ratio from the steering input means to the steered wheels in the configuration of claim 1 so as to effectively achieve the main problems described above. Steering transmission ratio control means is included, and the steering transmission ratio control means is configured to reduce the steering transmission ratio when the abnormality occurs (configuration of claim 2).

  According to the second aspect of the present invention, the steering transmission ratio is reduced when an abnormality occurs in which the front-rear distribution of the roll stiffness is closer to the rear wheel than in the normal state, so that the vehicle turning response to the driver's steering operation is reduced. The steering angle of the steered wheels can be controlled so that the performance is reliably reduced.

  According to the present invention, in order to effectively achieve the main problems described above, in the configuration of claim 1 or 2, the steering angle control means includes four-wheel steering control means, and the four-wheel steering is provided. The control means is configured to correct the control amount of the steering angle of the rear wheel to the same phase as the front wheel when the abnormality occurs (configuration of claim 3).

  According to the third aspect of the present invention, when an abnormality occurs in which the front-rear distribution of roll rigidity is closer to the rear wheel than in the normal state, the control amount of the steering angle of the rear wheel is corrected to the same phase as the front wheel. The steering angle of the rear wheels can be controlled so that the turning response of the vehicle to the driver's steering operation is surely reduced.

  According to the present invention, in order to effectively achieve the above main problem, in the configuration of claim 4, the steering angle control means is configured to set a target yaw rate of the vehicle based on a target yaw attenuation coefficient and a steering angle. And calculating the target steering angle of the wheel based on the target yaw rate and the steering angle, and controlling the steering angle of the wheel to be the target steering angle, and when the abnormality occurs, the target yaw attenuation coefficient It is comprised so that may be enlarged (structure of Claim 5).

  According to the configuration of claim 5, the steering angle control means calculates the target yaw rate of the vehicle based on the target yaw attenuation coefficient and the steering angle, calculates the target steering angle of the wheels based on the target yaw rate and the steering angle, The wheel yaw angle is controlled so as to become the target rudder angle, and the target yaw attenuation coefficient is increased when an abnormality occurs in the roll stiffness control means that the roll stiffness front-rear distribution is closer to the rear wheel than normal. Therefore, it is possible to calculate the target yaw rate so that the fluctuation of the yaw rate of the vehicle accompanying the steering operation of the driver is quickly attenuated, thereby ensuring the running stability of the vehicle when the steering operation is performed by the driver. The steering angle of the wheel can be controlled to improve.

  According to the invention, the roll stiffness control means includes a front wheel side active stabilizer device and a rear wheel side active stabilizer device that increase the roll stiffness of the vehicle when the wheel turns. The steering angle control means has a roll stiffness on the rear wheel side that is increased or decreased by the front wheel side active stabilizer device when the roll stiffness on the front wheel side is reduced as compared to a normal time or is increased or decreased by the rear wheel side active stabilizer device. It is configured to determine that the abnormality has occurred when increased as compared to normal time (structure of claim 6).

  According to the configuration of the above sixth aspect, when the roll rigidity on the front wheel side that is increased or decreased by the front wheel side active stabilizer device is lower than that in the normal state, or the roll rigidity on the rear wheel side that is increased or decreased by the rear wheel side active stabilizer device. When the roll rigidity increases compared to normal, it is determined that an abnormality has occurred where the roll rigidity front-rear distribution is closer to the rear wheel than normal, so the roll rigidity front-rear distribution is closer to the rear wheel than normal. When such an abnormality occurs in the roll stiffness control means, it can be reliably determined.

[Preferred embodiment of problem solving means]
According to one preferred aspect of the present invention, in the configuration according to any one of the first to third or sixth aspects, the steering angle control means is configured so that the front-rear distribution of the roll stiffness is smaller than that when the roll stiffness on the front wheel side is reduced. Then, when an abnormality that is close to the rear wheel occurs in the roll stiffness control means, the steering angle of the wheel is controlled so that the turning responsiveness of the vehicle to the driver's steering operation is reduced (Preferred Mode 1). .

  According to another preferred aspect of the present invention, in the configuration according to any one of claims 4 to 6, the steering angle control means is configured such that the front-rear distribution of roll rigidity is smaller than that when the roll rigidity on the front wheel side is reduced. Then, when an abnormality that is closer to the rear wheel occurs in the roll stiffness control means, the steering angle of the wheel is controlled so as to increase the yaw damping characteristic of the vehicle (preferred aspect 2).

  According to another preferred aspect of the present invention, in the configuration of the above-mentioned claims 1 to 3 or 6 or the preferred aspect 1, the rudder angle control means is configured so that the roll rigidity on the rear wheel side is increased. When an abnormality that is closer to the rear wheel than the normal distribution of rigidity occurs in the roll rigidity control means, the steering angle of the wheel is not controlled so that the turning response of the vehicle to the driver's steering operation is reduced. Further, it is configured to reduce the control amount of the roll rigidity on the rear wheel side (preferred aspect 3).

  According to another preferred aspect of the present invention, in the configuration of the above-mentioned claims 4 to 6 or the preferred aspect 2, the steering angle control means is configured to increase the roll rigidity by increasing the roll rigidity on the rear wheel side. When an abnormality occurs in the roll stiffness control means that the front-rear distribution is closer to the rear wheel compared to the normal distribution, the roll stiffness on the rear wheel side is controlled without controlling the steering angle of the wheel so that the yaw damping characteristic of the vehicle is increased. It is comprised so that control amount may be reduced (Preferable aspect 4).

  According to another preferred aspect of the present invention, in the configuration of claim 2 or preferred aspect 1 or 3, the steering angle control means calculates a target steering gear ratio, and based on the target steering gear ratio. The target steering angle of the front wheels is calculated and controlled so that the steering angle of the front wheels becomes the target steering angle. When a deviation abnormality occurs in the roll stiffness control means, the target steering gear ratio is configured to be increased (preferred aspect 5).

  According to another preferred aspect of the present invention, in the configuration of the above-mentioned claim 4 or the above-mentioned preferred aspects 1 to 4, the steering angle control means has a target steering gear when the vehicle speed is high compared to when the vehicle speed is low. It is configured to increase the amount of increase in the ratio (preferred aspect 6).

  According to another preferred aspect of the present invention, in the configuration of claim 3 or preferred aspect 2 or 4, the steering angle control means calculates a target yaw gain, and based on the target yaw gain, The target rudder angle is calculated and controlled so that the rudder angle of the rear wheels becomes the target rudder angle. When a certain abnormality occurs in the roll stiffness control means, the target yaw gain is configured to be reduced (preferred aspect 7).

  According to another preferred aspect of the present invention, in the configuration of the above-mentioned claim 4 or the above-mentioned preferred aspects 1 to 4, the steering angle control means is capable of setting the target yaw gain when the vehicle speed is high compared to when the vehicle speed is low. It is configured to increase the reduction amount (preferred aspect 8).

  According to another preferred aspect of the present invention, in the configuration of claim 4 or preferred aspects 1 to 4, the target steering angles of the front wheels and the rear wheels are calculated based on the target yaw rate and the steering angle, It is comprised so that it may control so that the rudder angle of a front wheel and a rear wheel may become the respectively corresponding rudder angle (preferable aspect 9).

  According to another preferred aspect of the present invention, in the configuration of the above-mentioned claim 5 or the preferred aspect 9, the steering angle control means has a target yaw attenuation coefficient that is higher when the vehicle speed is higher than when the vehicle speed is low. It is comprised so that an increase amount may be enlarged (preferred aspect 10).

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

  FIG. 1 is a schematic configuration diagram showing a vehicle travel control apparatus according to a first embodiment of the present invention applied to a vehicle having an active stabilizer device on the front wheel side and the rear wheel side and capable of controlling the steering angle of the front wheel.

  In FIG. 1, 10FL and 10FR indicate the left and right front wheels of the vehicle 12, respectively, and 10RL and 10RR indicate the left and right rear wheels of the vehicle 12, respectively. An active stabilizer device 16 is provided between the left and right front wheels 10FL and 10FR, and an active stabilizer device 18 is provided between the left and right rear wheels 10RL and 10RR. The active stabilizer devices 16 and 18 function as roll stiffness changing means for applying an anti-roll moment to the vehicle (vehicle body) and increasing / decreasing the roll stiffness on the front wheel side and the rear wheel side as required.

  The active stabilizer device 16 is integrally connected to a pair of torsion bar portions 16TL and 16TR extending coaxially with each other along an axis extending in the lateral direction of the vehicle, and to the outer ends of the torsion bar portions 16TL and 16TR, respectively. And a pair of arm portions 16AL and 16AR. The torsion bar portions 16TL and 16TR are respectively supported by a vehicle body not shown in the drawing via brackets not shown in the drawing so as to be rotatable around its own axis. The arm portions 16AL and 16AR extend in the longitudinal direction of the vehicle so as to intersect the torsion bar portions 16TL and 16TR, respectively, and the outer ends of the arm portions 16AL and 16AR are respectively left and right through rubber bush devices not shown in the drawing. The front wheels 10FL and 10FR are connected to suspension members 14FL and 14FR such as suspension arms.

  The active stabilizer device 16 has an actuator 20F between the torsion bar portions 16TL and 16TR. Actuator 20F has a built-in electric motor, and rotationally drives a pair of torsion bar portions 16TL and 16TR as necessary, so that torsional stress is generated when the left and right front wheels 10FL and 10FR bounce and rebound in opposite phases to each other. Thus, the force to suppress the bounce and rebound of the wheel is changed, thereby increasing or decreasing the anti-roll moment applied to the vehicle at the position of the left and right front wheels, and variably controlling the roll rigidity of the vehicle on the front wheel side.

  Similarly, the active stabilizer device 18 has a pair of torsion bar portions 18TL and 18TR extending coaxially with each other along an axis extending in the lateral direction of the vehicle, and the outer ends of the torsion bar portions 18TL and 18TR, respectively. It has a pair of arm portions 18AL and 18AR connected together. The torsion bar portions 18TL and 18TR are respectively supported by a vehicle body not shown in the drawing via brackets not shown in the drawing so as to be rotatable around its own axis. The arm portions 18AL and 18AR extend in the longitudinal direction of the vehicle so as to intersect the torsion bar portions 18TL and 18TR, respectively, and the outer ends of the arm portions 18AL and 18AR are respectively left and right through rubber bushing devices not shown in the drawing. The suspension members 14RL and 14RR such as the suspension arms of the rear wheels 10RL and 10RR are connected.

  The active stabilizer device 18 has an actuator 20R between the torsion bar portions 18TL and 18TR. The actuator 20R has a built-in electric motor, and if necessary, the pair of torsion bar portions 18TL and 18TR are driven to rotate relative to each other, so that the left and right rear wheels 10RL and 10RR bounce and rebound in opposite phases. The force that suppresses the bounce and rebound of the wheel is changed by the stress, whereby the anti-roll moment applied to the vehicle at the positions of the left and right rear wheels is increased and decreased, and the roll rigidity of the vehicle on the rear wheel side is variably controlled.

  Since the structures of the active stabilizer devices 16 and 18 do not form the gist of the present invention, any structure known in the art can be used as long as the roll rigidity of the vehicle can be variably controlled. However, for example, the active stabilizer device described in the specification and drawings of Japanese Patent Application No. 2003-324212 (reference number PA03-374) relating to the application of the present applicant, that is, a drive gear fixed to the inner end of one torsion bar portion An electric motor having an attached rotating shaft and a driven gear that is fixed to the inner end of the other torsion bar portion and meshes with the driving gear. The driving gear and the driven gear transmit the rotation of the driving gear to the driven gear. The active stabilizer device is preferably a gear that does not transmit the rotation of the driven gear to the drive gear.

  The actuators 20F and 20R of the active stabilizer devices 16 and 18 are controlled by the electronic control device 22 controlling the control current for the motor. Although not shown in detail in FIG. 1, the electronic control unit 22 includes a CPU, a ROM, a RAM, and an input / output port device, which are connected to each other via a bidirectional common bus and a drive circuit. It may be better.

  In the illustrated embodiment, as shown in FIG. 1, the left and right front wheels 10FL and 10FR are driven in response to the operation of the steering wheel 24 by the driver. 26 is steered by the rack bar 28 and the tie rods 30L and 30R.

  The steering wheel 24 is drivingly connected to the pinion shaft 40 of the power steering device 26 via an upper steering shaft 32, a turning angle varying device 34, a lower steering shaft 36, and a universal joint 38. In the illustrated embodiment, the turning angle varying device 34 is connected to the lower end of the upper steering shaft 32 on the side of the housing 34A and is connected to the upper end of the lower steering shaft 36 on the side of the rotor 34B. An electric motor 42 for turning driving is included.

  Thus, the steering angle varying device 34 drives the lower steering shaft 36 to rotate relative to the upper steering shaft 32, 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 24. That is, it functions as a steering gear ratio variable means for changing the steering transmission ratio (the reciprocal of the steering gear ratio), and the left and right front wheels 10FL and 10FR are auxiliary-steered relative to the steering wheel 14 for the purpose of vehicle travel control. It functions as an automatic steering device that is driven, and is controlled by the electronic control device 44. Although not shown in detail in FIG. 1, the electronic control unit 44 also has a CPU, a ROM, a RAM, and an input / output port unit, which are connected to each other via a bidirectional common bus and a drive circuit. It may be better.

  As shown in FIG. 1, the electronic control unit 22 includes a signal indicating the vehicle lateral acceleration Gy detected by the lateral acceleration sensor 48, a signal indicating the vehicle speed V detected by the vehicle speed sensor 50, a rotation angle sensor 52F, Signals indicating the actual rotation angles φF and φR of the actuators 20F and 20R detected by 52R are input.

  On the other hand, the electronic control unit 44 indicates the signal indicating the steering angle θ detected by the steering angle sensor 56 and the relative rotation angle θre detected by the rotation angle sensor 58, that is, the relative rotation angle of the lower steering shaft 36 with respect to the upper steering shaft 32. The signal shown is input. The electronic control units 22 and 44 communicate with each other and exchange necessary signals.

  The lateral acceleration sensor 48 and the steering angle sensor 56 detect the lateral acceleration Gy and the steering angle θ with positive values generated when the vehicle turns left, and the rotation angle sensor 58 detects the relative turning of the left and right front wheels in the left turning direction. The relative rotation angle θre is detected with the case being positive.

  In accordance with the flowchart shown in FIG. 2, the electronic control unit 22 determines whether or not the active stabilizer device 16 or 18 has an abnormality that is closer to the rear wheel than the normal distribution of roll rigidity. When the active stabilizer devices 16 and 18 are normal, the roll moment acting on the vehicle is estimated based on at least the lateral acceleration Gy of the vehicle. When the magnitude of the roll moment is greater than or equal to the reference value, the anti-rolling direction is canceled. A target anti-roll moment Mat of the vehicle is calculated so that the roll moment increases.

  The electronic control unit 22 calculates the target anti-roll moment Maft of the front wheel and the target anti-roll moment Mart of the rear wheel based on the target anti-roll moment Mat and the target roll stiffness distribution ratio Rmf of the front wheel, and the target anti-roll moment Maft and Mart. Based on the above, the target rotation angles φFt and φRt of the actuators 20F and 20R of the active stabilizer devices 16 and 18 are calculated, respectively, and control is performed so that the rotation angles φF and φR of the actuators 20F and 20R become the corresponding target rotation angles φFt and φRt, respectively. Thus, the roll of the vehicle at the time of turning or the like is reduced with a roll rigidity having a preferable front-rear distribution ratio.

  Further, the electronic control unit 22 may detect a gain abnormality in the rear wheel side active stabilizer device 18 or the like when an abnormality in the active stabilizer device 16 or 18 occurs in the active stabilizer device 16 or 18 as compared with a normal distribution of roll rigidity. It is determined whether or not the roll rigidity on the rear wheel side is increased due to the above, and when the roll rigidity on the rear wheel side is increased, the control amount of the active stabilizer device 18 on the rear wheel side is reduced and corrected. Thus, the active stabilizer devices 16 and 18 are controlled so that the front / rear distribution of the roll rigidity is closer to the front wheels than in the uncorrected case and the roll of the vehicle is reduced as much as possible.

  On the other hand, when the roll stiffness on the front wheel side is reduced due to an abnormality in the active stabilizer device 16 on the front wheel side, it is impossible to control the front-rear distribution of roll stiffness closer to the front wheel without reducing the roll stiffness on the rear wheel side. Since it is possible, the electronic control unit 22 does not control the active stabilizer device 16 on the front wheel side, and controls only the active stabilizer device 18 on the rear wheel side. Further, the electronic control unit 22 sets a flag Fst indicating 1 that the roll rigidity on the front wheel side is lowered and an abnormality that is closer to the rear wheel than the normal distribution of the roll rigidity has occurred. A signal indicating the flag Fst is output to the electronic control unit 44.

  Thus, the active stabilizer devices 16 and 18, the electronic control device 22, the lateral acceleration sensor 48, and the like function as a roll stiffness variable device that increases or decreases the roll stiffness of the vehicle by increasing or decreasing the anti-roll moment when an excessive roll moment acts on the vehicle. And preventing excessive rolling of the vehicle.

  Further, the electronic control unit 44 calculates the target steering gear ratio Rgt based on the vehicle speed V according to the flowchart shown in FIG. 3, and the front wheel based on the steering angle θ indicating the driver's steering operation amount and the target steering gear ratio Rgt. The target rudder angle δft of is calculated. In this case, the electronic control unit 44 has a flag Fst of 1, and when an abnormality occurs that is closer to the rear wheel than the normal distribution of roll rigidity, the electronic control device 44 is compared with the case where the abnormality does not occur. The target steering gear ratio Rgt is calculated to a large value.

  The electronic control unit 44 achieves a predetermined steering characteristic by controlling the turning angle varying device 34 so that the steering angle δf of the front wheels becomes the target steering angle δft. When the vehicle is close to the rear wheel, the turning response characteristic of the vehicle with respect to the driver's steering operation is reduced, thereby reducing the influence of the roll rigidity distribution near the rear wheel and reducing the running stability of the vehicle. Effectively reduce.

  It should be noted that the determination as to whether or not an abnormality has occurred that is closer to the rear wheel than the normal distribution of roll stiffness does not form the gist of the present invention, and is any arbitrary method known in the art. For example, whether the roll stiffness is larger than the target roll stiffness based on the magnitude relationship between the target rotation angles φFt and φRt of the actuators 20F and 20R and the corresponding actual rotation angles φF and φR, respectively. This may be done by determining whether or not.

  Next, the vehicle travel control in the illustrated embodiment 1 will be described with reference to the flowcharts shown in FIGS. FIGS. 2 and 3 are flow charts showing a roll rigidity control routine and a front wheel rudder angle control routine, respectively. Each control is started by closing an ignition switch not shown in the figure, and is performed at predetermined time intervals. Will be executed repeatedly.

  In step 210 of the roll stiffness control routine shown in FIG. 2, a signal indicating the vehicle lateral acceleration Gy is read, and in step 215, the front and rear distribution of the roll stiffness is compared with the normal time. Then, it is determined whether or not an abnormality near the rear wheel has occurred in the active stabilizer device 16 or 18, and if an affirmative determination is made, the process proceeds to step 250. If a negative determination is made, the process proceeds to step 220. The flag Fst is reset to zero.

In step 225, the target roll stiffness distribution ratio Rmf of the front wheels is calculated as a value greater than 0 and less than 1 so that it increases as the vehicle speed V increases. In step 230, for example, the lateral acceleration Gy of the vehicle increases. The target anti-roll moment Mat is calculated on the basis of the lateral acceleration Gy of the vehicle so that the target anti-roll moment Mat increases as the value increases. Maft and rear wheel target anti-roll moment Mart are calculated.
Maft = RmfMat (1)
Mart = (1-Rmf) Mat (2)

  In step 240, the target rotational angles φft and φrt of the actuators 20F and 20R of the active stabilizer devices 16 and 18 are calculated based on the front wheel target anti-roll moment Maft and the rear wheel target anti-roll moment Mart, respectively. In this case, the rotation angles φf and φr of the actuators 20F and 20R are controlled to be the target rotation angles φft and φrt, respectively.

  In step 250, it is determined whether or not the roll rigidity of the rear wheel is increased. If a negative determination is made, the process proceeds to step 265. If an affirmative determination is made, the flag is set in step 255. Fst is reset to 0, and in step 260, the target rotational angles φft and φrt of the actuators 20F and 20R of the active stabilizer devices 16 and 18 are calculated in the same manner as in steps 225 to 240 described above, and the rear wheels Since the control amount of the active stabilizer device 18 on the side is reduced and corrected, the active stabilizer devices 16 and 18 are controlled so that the front / rear distribution of the roll stiffness is closer to the front wheels than in the non-corrected case and the roll of the vehicle is reduced as much as possible. Is done.

  In step 265, the flag Fst is set to 1. In step 270, the target rotational angles φft and φrt of the actuators 20F and 20R of the active stabilizer devices 16 and 18 are the same as in steps 225 to 240 described above. And the active stabilizer devices 16 and 18 are controlled based on the target rotation angles φft and φrt, respectively.

  In this case, the actual control amount of the active stabilizer device 16 on the front wheel side is smaller than the target rotation angle φft. Further, when the abnormality in the front wheel side active stabilizer device 16 is an abnormality in which the roll rigidity cannot be exhibited, only the rear wheel side active stabilizer device 18 is controlled without controlling the front wheel side active stabilizer device 16. It's okay.

  In step 310 of the front wheel steering angle control routine shown in FIG. 3, a signal indicating the steering angle θ is read, and in step 320, whether or not the flag Fst is 1 is determined. The determination, that is, whether or not an abnormality that is closer to the rear wheel than the normal distribution of roll rigidity due to an increase in the roll rigidity on the rear wheel side has occurred is made, and an affirmative determination was made Sometimes, the process proceeds to Step 230, and when a negative determination is made, the process proceeds to Step 340.

  In step 330, the target steering gear ratio Rgt is calculated from the map corresponding to the graph indicated by the solid line in FIG. 4 based on the vehicle speed V. In step 340, the target steering gear ratio Rgt is calculated based on the vehicle speed V in FIG. The target steering gear ratio Rgt is calculated from the map corresponding to the graph indicated by the broken line.

  Note that the standard steering gear ratio is Rgo (a positive constant), and the target steering angle δft is a steering angle δw (= θ / Rgo) corresponding to the driver's steering operation and control steering to achieve a predetermined steering characteristic. It is the sum with the angle δc. Further, the control of the steering characteristic itself does not form the gist of the present invention, and the target steering gear ratio Rgt may be calculated in an arbitrary manner known in the art. For example, the transient response of the vehicle to the steering can be calculated. It may also be changed by the steering speed to improve.

  Further, as can be seen from a comparison between the solid line and the broken line in FIG. 4, the target steering gear ratio Rgt calculated in step 340 is the target steering gear ratio (for the active stabilizer devices 16 and 18) for achieving a predetermined steering characteristic. This is calculated as the sum of the target steering gear ratio Rgt) calculated in step 330 at the normal time and the correction amount ΔRgt for reducing the turning responsiveness of the vehicle to the driver's steering operation.

In step 350, a target rudder angle δft of the front wheels for achieving a predetermined steering characteristic is calculated according to the following equation (3).
δft = θ / Rgt (3)

  In step 360, based on the target steering angle δft of the front wheels, the target relative rotation angle of the steering angle varying device 24 for changing the steering angle δf of the front wheels to the target steering angle δft in a manner known in the art. θret is calculated, and in step 370, the steered angle varying device 24 is controlled so that the relative rotational angle θre of the steered angle varying device 24 becomes the target relative rotational angle θret. Control is performed to achieve the target rudder angle δft.

  Thus, according to the illustrated embodiment 1, when the active stabilizer devices 16 and 18 are normal, an affirmative determination is made at step 215, and the target roll stiffness distribution ratio Rmf of the front wheels is calculated at step 225, In step 230, the target anti-roll moment Mat is calculated based on the lateral acceleration Gy of the vehicle. In step 235, the target anti-roll moment of the front wheels for achieving the target anti-roll moment Mat with the target roll stiffness distribution ratio Rmf. Maft and the target anti-roll moment Mart of the rear wheel are calculated, and in steps 240 and 245, the active stabilizer devices 16 and 18 are controlled so that the target anti-roll moments Maft and Mart are achieved. Is prevented.

  Further, when the roll stiffness on the rear wheel side increases and the abnormality in which the front and rear distribution of the roll stiffness is closer to the rear wheel than in the normal state occurs in the active stabilizer device 16 or 18, a negative determination is made in step 215. In step 250, an affirmative determination is made, and in step 260, the control amount of the active stabilizer device 18 on the rear wheel side is reduced and corrected, so that the front and rear distribution of roll rigidity is compared with the case of non-correction. It becomes closer to the front wheel and the roll of the vehicle is reduced as much as possible.

  Further, when the roll stiffness on the front wheel side is reduced and the abnormality in which the front and rear distribution of the roll stiffness is closer to the rear wheel than in the normal state occurs in the active stabilizer device 16 or 18, the result is negative in steps 215 and 250. In step 265, the flag Fst is set to 1. In step 270, the active stabilizer devices 16 and 18 are controlled based on the target rotation angles φft and φrt, respectively.

  Further, according to the first embodiment shown in the figure, when the roll rigidity on the front wheel side is reduced and the front / rear distribution of the roll rigidity is not an abnormality that is closer to the rear wheel as compared with the normal time, the result is negative in step 320. In step 330, the target steering gear ratio Rgt is calculated based on the vehicle speed V, and in step 350, the target steering angle δft of the front wheels for achieving a predetermined steering characteristic is calculated. At 370, the turning angle varying device 24 is controlled so that the steering angle δf of the front wheels becomes the target steering angle δft.

  On the other hand, when the roll rigidity on the front wheel side is lowered, and an abnormality occurs in which the front and rear distribution of the roll rigidity is closer to the rear wheel as compared with the normal time, an affirmative determination is made in step 320 and step 340 is performed. In this case, the target steering gear ratio Rgt is calculated to be a larger value than when no abnormality has occurred, and steps 350 to 370 are executed based on the target steering gear ratio Rgt.

  Therefore, according to the first embodiment shown in the figure, the roll rigidity on the front wheel side is reduced, so that an abnormality in which the front and rear distribution of the roll rigidity is closer to the rear wheel than in the normal state occurs in the active stabilizer device 16 or 18, and the vehicle Even if the steering characteristic changes to the oversteer side compared to the normal state, the steering angle of the front wheels is controlled so as to suppress the change of the steering characteristic, and the turning responsiveness of the vehicle to the driver's steering operation can be reduced. Therefore, it is possible to reliably reduce a decrease in the running stability of the vehicle due to the change of the steer characteristic to the oversteer side.

  Further, according to the first embodiment shown in the figure, even if an abnormality is caused in the active stabilizer device 16 or 18 that the roll rigidity on the front wheel side decreases and the front-rear distribution of the roll rigidity is closer to the rear wheel than in the normal state, Since the control amount of the active stabilizer device 18 on the rear wheel side is not reduced, the roll rigidity on the rear wheel side is not reduced, so that the roll rigidity of the entire vehicle is reduced and the roll resonance frequency of the vehicle becomes the yaw resonance frequency. It is possible to reliably reduce a decrease in the running stability of the vehicle due to approaching the vehicle, and to reduce the possibility that the roll of the vehicle during turning will be excessive.

  In particular, according to the first embodiment shown in the drawing, the target steering gear ratio in the case where an abnormality in which the front-rear distribution of the roll rigidity is closer to the rear wheel than in the normal state due to the decrease in the roll rigidity on the front wheel side occurs. Rgt is calculated as the sum of the target steering gear ratio for achieving the predetermined steering characteristic and the correction amount ΔRgt for reducing the turning response of the vehicle with respect to the driver's steering operation. While achieving this, it is possible to reliably reduce the decrease in the running stability of the vehicle due to the change of the steering characteristic toward the oversteer side.

  Further, according to the first embodiment shown in the drawing, the target steering gear ratio in the case where an abnormality in which the front-rear distribution of the roll rigidity is closer to the rear wheel than in the normal state due to the decrease in the roll rigidity on the front wheel side occurs. Rgt is calculated so that the correction amount ΔRgt for decreasing the turning response of the vehicle to the driver's steering operation increases as the vehicle speed V increases. Therefore, regardless of the vehicle speed V, the correction amount ΔRgt of the target steering gear ratio is Compared with the case where it is constant, the degree of decrease in the vehicle turning response to the driver's steering operation can be optimally controlled according to the vehicle speed.

  Further, according to the illustrated embodiment 1, since only the steering angle of the front wheels is controlled, there is no need to control the steering angle of the rear wheels, and hence no rear wheel steering device is required, and the steering angle of the rear wheels is not required. Compared with the case where it is controlled, the steering angle of the steered wheels can be controlled easily.

  In the illustrated embodiment 1, the target steering gear ratio Rgt calculated in step 330 when the active stabilizer devices 16 and 18 are normal is calculated as a target steering gear ratio for achieving a predetermined steering characteristic. However, the target steering gear ratio Rgt under normal conditions may be constant regardless of the vehicle speed V.

  Similarly, the target steering gear ratio Rgt when the front-wheel-side roll rigidity is reduced and the front-rear distribution of roll rigidity is closer to the rear wheels than in the normal state is a predetermined steering characteristic. Is calculated as the sum of the target steering gear ratio for achieving the above and the correction amount ΔRgt for reducing the turning response of the vehicle to the driver's steering operation, but an abnormality has occurred As long as the target steering gear ratio Rgt at normal time is larger than the normal target steering gear ratio Rgt, the target steering gear ratio Rgt at normal time may be calculated, for example, as the sum of a constant target steering gear ratio at normal time and the correction amount ΔRgt.

  FIG. 5 is a schematic configuration diagram showing a second embodiment of the vehicle travel control device according to the present invention applied to a vehicle capable of controlling the steering angles of the front wheels and the rear wheels. In FIG. 5, the same members as those shown in FIG. 1 are denoted by the same reference numerals as those shown in FIG.

  In the second embodiment, the left and right rear wheels 10RL and 10RR are separated from the left and right front wheels 10FL and 10FR by the hydraulic or electric power steering device 54 of the rear wheel steering device 52 and the tie rods 56L and 56R. The rear wheel steering device 52 is controlled by the electronic control device 44 through 56R.

  The electronic control device 22 controls the active stabilizer devices 16 and 18 in the same manner as in the first embodiment, and the electronic control device 44 controls the active stabilizer devices 16 and 18 in the first embodiment. In the same manner as in a certain case, the target steering angle δft of the front wheels is calculated based on the vehicle speed V so that a predetermined steering characteristic is achieved, and the steering angle varying device so that the steering angle of the front wheels becomes the target steering angle δft 24 is controlled.

  Further, the electronic control unit 44 calculates the target yaw gain Kygt based on the vehicle speed V, and uses the reverse model of the actual vehicle, which receives the target yaw gain Kygt as an input and outputs the rear wheel target rudder angle δrt. And the rear wheel steering device 52 is controlled such that the rear wheel steering angle becomes the target steering angle δrt.

  In particular, the electronic control unit 44 is configured so that the active stabilizer device 16 or 18 has an abnormality in which the front-wheel-side roll rigidity is lowered and the front-rear distribution of the roll rigidity is closer to the rear wheel than in the normal state. The target yaw gain Kygt is calculated according to the vehicle speed V so as to be smaller than when the devices 16 and 18 are normal, thereby reducing the turning response of the vehicle to the steering operation.

  FIG. 6 is a flowchart showing a control routine for the steering angle of the rear wheels in the second embodiment. Note that the control according to the flowchart shown in FIG. 6 is also started by closing an ignition switch (not shown), and is repeatedly executed every predetermined time.

  In the second embodiment, in step 520, whether or not the flag Fst is 1 is determined in the same manner as in the first embodiment, that is, the roll rigidity on the front wheel side is reduced. A determination is made as to whether or not an abnormality has occurred that is closer to the rear wheel than the normal distribution of roll rigidity. If an affirmative determination is made, the process proceeds to step 640. If a negative determination is made, the process proceeds to step 640. Proceed to 630.

  In step 630, the target yaw gain Kygt is calculated from the map corresponding to the graph shown by the solid line in FIG. 7 based on the vehicle speed V. In step 640, the broken line in FIG. The target yaw gain Kygt is calculated from the map corresponding to the graph indicated by.

  As can be seen from the comparison between the solid line and the broken line in FIG. 7, the target steering gear ratio Rgt gradually increases as the vehicle speed V increases in the low speed range, and slightly increases as the vehicle speed V increases in the medium and high speed range. Calculated to be smaller. Further, the target steering gear ratio Rgt calculated in step 640 at the time of abnormality is corrected so that the target steering gear ratio Rgt calculated in step 630 at the normal time decreases the turning responsiveness of the vehicle to the driver's steering operation. It is calculated as a value obtained by subtracting the amount ΔRgt.

  In step 650, the rear wheel target rudder angle δrt is calculated using an inverse model of the actual vehicle that receives the target yaw gain Kygt and outputs the rear wheel target rudder angle δrt. In step 660, the rear wheel target rudder angle δrt is calculated. The rear wheel steering device 52 is controlled so that the steering angle becomes the target steering angle δrt.

  Thus, according to the illustrated second embodiment, the active stabilizer devices 16 and 18 are controlled in the same manner as in the first embodiment, and in the same manner as in the case where the active stabilizer devices 16 and 18 are normal. By controlling the turning angle varying device 24, the steering angle of the front wheels is controlled so that a predetermined steering characteristic is achieved.

  Further, when the roll rigidity on the front wheel side is reduced and no abnormality occurs that is closer to the rear wheel as compared with the normal distribution of the roll rigidity, a negative determination is made in step 620 and in step 630. Then, the target yaw gain Kygt is calculated. In step 650, the rear wheel target rudder angle δrt is calculated based on the target yaw gain Kygt. In step 660, the rear wheel steer angle becomes the target rudder angle δrt. The steering device 52 is controlled.

  On the other hand, when the roll rigidity on the front wheel side is lowered, and an abnormality occurs in which the front and rear distribution of the roll rigidity is closer to the rear wheel as compared with the normal time, an affirmative determination is made in step 620 and step 640 is performed. In this case, the target yaw gain Kygt is calculated to a smaller value than when no abnormality has occurred, and steps 650 to 660 are executed based on the target yaw gain Kygt.

  Therefore, according to the second embodiment shown in the drawing, the roll rigidity on the front wheel side is reduced, so that an abnormality in which the front and rear distribution of the roll rigidity is closer to the rear wheel than in the normal state occurs in the active stabilizer device 16 or 18, and the vehicle Even if the steering characteristic changes to the oversteer side compared to normal, the yaw gain can be controlled so as to suppress the change of the steering characteristic, and the turning response of the vehicle to the driver's steering operation can be reduced. A decrease in the running stability of the vehicle due to the change of the steering characteristic toward the oversteer side can be reliably reduced.

  In particular, according to the second embodiment shown in the drawing, the target yaw gain Kygt in the case where an abnormality that is closer to the rear wheel than the normal distribution of the roll rigidity occurs due to a decrease in the roll rigidity on the front wheel side. When the vehicle speed V is higher, the correction amount ΔKygt for decreasing the turning responsiveness of the vehicle to the driver's steering operation is calculated to be larger. Therefore, regardless of the vehicle speed V, the target yaw gain correction amount ΔRgt is constant. As compared with this, the degree of decrease in the turning response of the vehicle with respect to the driver's steering operation can be optimally controlled according to the vehicle speed.

  In the illustrated embodiment 2, the target steering angle δft of the front wheels is calculated based on the vehicle speed V so as to achieve a predetermined steering characteristic, and the steering angle is set so that the steering angle of the front wheels becomes the target steering angle δft. Although the variable device 24 is controlled, the configuration of the second embodiment may be applied to a vehicle in which the turning angle variable device 24 is not provided, that is, a vehicle in which the steering angle of the front wheels is not controlled.

  FIG. 8 is a flowchart showing a control routine for the steering angles of the front wheels and the rear wheels in the third embodiment of the vehicle travel control apparatus according to the present invention applied to a vehicle capable of controlling the steering angles of the front wheels and the rear wheels. . The control by the routine shown in FIG. 8 is also started by closing an ignition switch not shown in the figure, and is repeatedly executed at predetermined time intervals.

  Also in the third embodiment, the left and right rear wheels 10RL and 10RR are separated from the left and right front wheels 10FL and 10FR by the hydraulic or electric power steering device 54 of the rear wheel steering device 52 and the tie rods 56L and 56R. The steering angle variable device 24 and the rear wheel steering device 52 are controlled by the electronic control device 44 according to the routine shown in FIG.

  In this third embodiment, it is determined in step 520 whether or not the flag Fst is 1 in the same manner as in the first embodiment, that is, the roll rigidity on the front wheel side is reduced. A determination is made as to whether or not an abnormality has occurred that is closer to the rear wheel than the normal distribution of roll rigidity. When an affirmative determination is made, the process proceeds to step 840, and when a negative determination is made, the process proceeds to step 840. Go to 830.

  In step 830, the target yaw attenuation coefficient Ksdt is calculated from the map corresponding to the graph shown by the solid line in FIG. 9 based on the vehicle speed V. In step 840, the target yaw attenuation coefficient Ksdt is calculated based on the vehicle speed V in FIG. The target yaw attenuation coefficient Ksdt is calculated from a map corresponding to the graph indicated by the broken line.

  As can be seen from the comparison between the solid line and the broken line in FIG. 9, the target yaw attenuation coefficient Ksdt is calculated so as to gradually decrease as the vehicle speed V increases over the entire vehicle speed range. Further, the target yaw attenuation coefficient Ksdt calculated in step 8640 at the time of abnormality is set so that the target yaw attenuation coefficient Ksdt calculated in step 830 at the time of normality increases the attenuation of the yaw motion of the vehicle. Is calculated as a value obtained by adding a correction amount ΔKsdt for reducing the turning response of the vehicle.

  In step 850, the target yaw rate γt of the vehicle is calculated using a two-wheel model of the vehicle that receives the steering angle θ and the target yaw attenuation coefficient Ksdt and outputs the target yaw rate γt of the vehicle. In step 860, steering is performed. Based on the angle θ and the target yaw rate γt, the front wheel target rudder angle δft and the rear wheel target rudder angle δrt are calculated, and in step 870, the steered angle is variable so that the front wheel rudder angle δf becomes the target rudder angle δft. The device 24 is controlled, and the rear wheel steering device 52 is controlled so that the steering angle of the rear wheels becomes the target steering angle δrt.

  Thus, according to the third embodiment shown in the drawing, the roll rigidity on the front wheel side is reduced, so that an abnormality in which the front and rear distribution of the roll rigidity is closer to the rear wheel than in the normal state occurs in the active stabilizer device 16 or 18. Even if the steer characteristic changes to the oversteer side compared to the normal state, the yaw attenuation characteristic is increased so as to suppress the change of the steer characteristic, so that the fluctuation of the vehicle yaw rate due to the steering operation of the driver can be quickly accelerated. Since it can be attenuated, it is possible to reliably reduce the decrease in the running stability of the vehicle due to the change of the steering characteristic toward the oversteer side.

  In particular, according to the third embodiment shown in the drawing, the target yaw damping coefficient when the roll rigidity on the front wheel side decreases and the front / rear distribution of the roll rigidity is closer to the rear wheel than in the normal state occurs. Since Ksdt is calculated so that the correction amount ΔKsdt for reducing the turning response of the vehicle to the driver's steering operation increases as the vehicle speed V increases, the correction amount ΔKsdt of the target yaw attenuation coefficient is not limited to the vehicle speed V. Compared with the case where it is constant, the degree of decrease in the vehicle turning response to the driver's steering operation can be optimally controlled according to the vehicle speed.

  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 each of the above-described embodiments, when the roll rigidity on the rear wheel side increases and the front / rear distribution of the roll rigidity has an abnormality that is closer to the rear wheel than in the normal state, in step 260. Further, the control amount of the active stabilizer device 18 on the rear wheel side is corrected to be reduced, so that the front-rear distribution of the roll stiffness is closer to the front wheel than the non-corrected case, and the roll of the vehicle is reduced as much as possible. When an affirmative determination is made in step 250, it is determined whether or not the control amount of the active stabilizer device 18 on the rear wheel side can be reduced and corrected to control the active stabilizer device 18 on the rear wheel side. If a positive determination is made, step 260 may be executed, and if a negative determination is made, the process may proceed to step 265.

  In each of the above-described embodiments, when an affirmative determination is made in step 215, that is, when there is an abnormality that is closer to the rear wheel than the normal distribution of roll rigidity, step At 250, it is determined whether or not the abnormality is an abnormality due to an increase in the roll rigidity on the rear wheel side, but steps 265 and 270 are performed without executing steps 250 to 260. It may be modified to be executed.

  In each of the above-described embodiments, the turning angle varying device 24 rotates the lower steering shaft 26 relative to the upper steering shaft 22 so that the left and right front wheels 10FL do not depend on the driver's steering operation. As long as the steering wheel can be steered independently of the driver's steering operation, for example, a steering angle variable device of a type that expands and contracts the tie rods 20L and 20R. Any configuration known in the art may be used.

  In the second and third embodiments, the rear wheel steering device 52 steers the left and right rear wheels 10RL and 10RR via the tie rods 56L and 56R by the hydraulic or electric power steering device 54. However, it may be of any construction known in the art, such as a rear wheel steering device of the type that expands and contracts tie rods 56L and 56R.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram showing a first embodiment of a vehicle travel control device according to the present invention applied to a vehicle having an active stabilizer device on a front wheel side and a rear wheel side and capable of controlling a steering angle of a front wheel. 3 is a flowchart showing a roll rigidity control routine in the first embodiment. 3 is a flowchart illustrating a control routine for a steering angle of a front wheel in the first embodiment. When the front wheel side and rear wheel side active stabilizer devices are normal (solid line), and the roll rigidity of the front wheel side decreases, an abnormality occurs that the front and rear distribution of roll rigidity is closer to the rear wheel than when normal. It is a graph which shows the relationship between the vehicle speed V and target steering gear ratio Rgt about the case where it exists (broken line). It is a schematic block diagram which shows Example 2 of the traveling control apparatus of the vehicle by this invention applied to the vehicle which has an active stabilizer apparatus in the front-wheel side and a rear-wheel side, and can control the steering angle of a front wheel and a rear wheel. 7 is a flowchart illustrating a control routine for a steering angle of a rear wheel in the second embodiment. When the front wheel side and rear wheel side active stabilizer devices are normal (solid line), and the roll rigidity of the front wheel side decreases, an abnormality occurs that the front and rear distribution of roll rigidity is closer to the rear wheel than when normal. It is a graph which shows the relationship between the vehicle speed V and the target yaw gain Kygt about the case (broken line). 12 is a flowchart illustrating a control routine for steering angles of front wheels and rear wheels in the third embodiment. When the front wheel side and rear wheel side active stabilizer devices are normal (solid line), and the roll rigidity of the front wheel side decreases, an abnormality occurs that the front and rear distribution of roll rigidity is closer to the rear wheel than when normal. It is a graph which shows the relationship between the vehicle speed V and the target yaw attenuation coefficient Ksgt about the case (broken line).

Explanation of symbols

16, 18 Active stabilizer device 20F, 20R Actuator 22 Electronic control device 34 Steering angle variable device 44 Electronic control device 48 Lateral acceleration sensor 50 Vehicle speed sensor 52F, 52R Rotation angle sensor 56 Steering angle sensor 58 Rotation angle sensor

Claims (6)

  A vehicle travel control device having a steering angle control means for controlling a steering angle of a wheel and a roll rigidity control means for variably controlling a roll rigidity of the vehicle, wherein the front and rear distribution of the roll rigidity is a rear wheel compared to a normal time. The steering angle control means controls the steering angle of the vehicle wheel so that the turning response of the vehicle to the steering operation of the driver is lowered when an abnormality that causes a deviation occurs in the roll rigidity control means. Travel control device.   The steering angle control means includes steering transmission ratio control means for variably controlling the steering transmission ratio from the steering input means to the steered wheels, and the steering transmission ratio control means reduces the steering transmission ratio when the abnormality occurs. The vehicle travel control apparatus according to claim 1.   The steering angle control means includes four-wheel steering control means, and the four-wheel steering control means corrects the control amount of the steering angle of the rear wheels to the same phase as the front wheels when the abnormality occurs. Item 3. The vehicle travel control device according to Item 1 or 2.   A steering control device for a vehicle having a steering angle control means for controlling a steering angle of a wheel and a roll rigidity control means for variably controlling the roll rigidity of the vehicle, wherein the front and rear distribution of the roll rigidity is a rear wheel as compared with a normal time. The vehicle travel control device according to claim 1, wherein when the roll rigidity control means has an abnormal deviation, the steering angle control means controls a steering angle of a wheel so that a yaw damping characteristic of the vehicle is increased.   The steering angle control means calculates a target yaw rate of the vehicle based on a target yaw attenuation coefficient and a steering angle, calculates a target steering angle of a wheel based on the target yaw rate and the steering angle, and the steering angle of the wheel is a target steering angle. The vehicle travel control apparatus according to claim 4, wherein the target yaw attenuation coefficient is increased when the abnormality occurs. The roll stiffness control means includes a front wheel side active stabilizer device and a rear wheel side active stabilizer device that increase the roll stiffness of the vehicle when the wheels turn, and the steering angle control means is a front wheel side that is increased or decreased by the front wheel side active stabilizer device. Determining that the abnormality has occurred when the roll rigidity of the rear wheel has decreased compared to normal or when the roll rigidity of the rear wheel increased or decreased by the rear wheel active stabilizer device has increased compared to normal. 6. The vehicle travel control device according to claim 1, wherein the vehicle travel control device is characterized in that:

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