JP4830569B2 - Vehicle travel control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce unnatural deviation of a vehicle due to roll steering by controlling a steering angle of a steering wheel so as to reduce influences of toe changes of wheels due to the roll steering when adhesion abnormality of a roll stiffness control device occurs, and to improve travel performance of a vehicle in such a state that the adhesion abnormality occurs on the roll stiffness control device more than ever. <P>SOLUTION: When the adhesion abnormality occurs on an active stabilizer device on a front wheel side or a rear wheel side, a deviation amount &Delta;&theta; due to the roll steering is computed when a vehicle is in a specific traveling state, and a target steering angle &delta;ft of front wheels is computed on the basis of a steering angle obtained by correcting a steering angle &theta; by subtracting the deviation amount &Delta;&theta; and a target steering gear ratio Rgt. Therefore, the steering angle of the front wheel is corrected so as to cancel the influence of the toe change of the wheels due to the roll steering, and the deviation of the vehicle due to the roll steering is prevented while attaining predetermined steering characteristics. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a vehicle travel control device, and more specifically, a steering wheel steering angle varying device capable of turning a steered wheel without depending on driver's steering, and roll stiffness control for variably controlling the roll stiffness of the vehicle. The present invention relates to a vehicle travel control device including the device.

  As one of travel control devices for vehicles such as automobiles, for example, as described in Patent Document 1 below, roll rigidity is variably controlled by rotationally driving a pair of torsion bars and a pair of torsion bars. In a vehicle equipped with an active stabilizer device having an actuator, the grip state of the steered wheels is estimated, and the active stabilizer device is controlled according to the grip state of the steered wheels, thereby controlling the roll rigidity of the vehicle. 2. Description of the Related Art A travel control device that controls roll motion is conventionally known.

According to such a travel control device, the roll rigidity of the vehicle is controlled according to the grip state of the steering wheel, so that the roll of the vehicle body is compared with the case where the roll rigidity of the vehicle is not controlled according to the grip state of the steering wheel. Exercise can be controlled appropriately.
JP 2005-96672 A

[Problems to be Solved by the Invention]
In general, an active stabilizer device changes the roll rigidity of a vehicle by rotating the left and right torsion bars relative to each other with the actuator. For example, the actuator is operated with the left and right torsion bars rotated relative to each other while the vehicle is turning. If there is an abnormality that cannot be driven, that is, a fixing abnormality that cannot change the roll rigidity of the vehicle, the left and right torsion bars remain rotated at a certain angle, and the roll rigidity of the vehicle depends on the roll direction of the vehicle. Will be in different states. Therefore, when the vehicle goes straight, one of the left and right wheels is in a bound state and the other wheel on the left and right is in a rebound state. The degree of the bound and rebound state is proportional to the relative rotation angle of the left and right torsion bars that are fixed.

  Further, in general, in a vehicle such as an automobile, the wheel is supported by a suspension arm that is pivotally supported by the vehicle body at one end and pivotally attached to the wheel support member at the other end. In other words, a roll steer occurs. This roll steer occurs only momentarily during normal driving of the vehicle, but if the bounce and rebound state of the wheel continues, the vehicle tries to deflect in the direction of toe change of the wheel due to the roll steer. The vehicle must be driven against the deflection, and the running performance of the vehicle is inevitably deteriorated.

  However, in the conventional traveling control device as described above for controlling the active stabilizer device, the problem associated with roll steer due to the abnormal fixation of the active stabilizer device and the countermeasures have not been sufficiently studied. There is a need for improvement.

  The problem of the sticking of the active stabilizer device is not limited to the electric active stabilizer device in which the actuator includes the electric motor and the reduction gear mechanism, and similarly occurs in the hydraulic active stabilizer device in which the actuator is operated by hydraulic pressure. In some cases, the same problem may occur when the means for changing the roll rigidity is an active suspension that changes the spring force of the suspension spring.

  The present invention has been made in view of the above-described points in a conventional travel control device for a vehicle equipped with a roll stiffness control device, and a main problem of the present invention is that a sticking abnormality occurs in the roll stiffness control device. The steering angle of the steered wheels is controlled so as to reduce the influence of wheel toe change caused by roll steer, thereby reducing unnatural deflection of the vehicle caused by roll steer. Compared to this, it is to improve the running performance of the vehicle in the situation where the sticking abnormality occurs in the roll stiffness control device.

[Means for Solving the Problems and Effects of the Invention]
According to the present invention, the main problem described above is that the configuration of claim 1, that is, the steering wheel rudder angle varying means capable of changing the rudder angle of the steered wheel irrespective of the driver's steering, and the steered angle of the steered wheel are In a vehicle travel control apparatus, comprising: a steered wheel rudder angle control unit that controls the steered wheel rudder angle varying unit so as to achieve a target rudder angle; and a roll stiffness varying unit that changes a roll stiffness of the vehicle. The steering angle control means is configured to detect the sticking based on the steering operation amount of the driver and the actual turning state amount of the vehicle when a sticking abnormality occurs in the roll stiffness varying means in which the roll stiffness of the vehicle varies depending on the roll direction of the vehicle. Steering for calculating a correction amount of the steering operation amount for reducing the deflection of the vehicle due to the abnormality and achieving a predetermined steering characteristic based on the steering operation amount corrected by the correction amount of the steering operation amount Calculate the target rudder angle of the wheel, Travel control device for a vehicle and controlling the steering wheel steering angle varying means on the basis of the target steering angle, or the second aspect, i.e. capable of changing the steering angle of the steering wheel regardless of the driver's steering Steering wheel steering angle variable means, steering wheel steering angle control means for controlling the steering wheel steering angle variable means so that the steering angle of the steering wheel becomes a target steering angle, and roll stiffness variable means for changing the roll rigidity of the vehicle In the vehicle travel control device, the steering wheel rudder angle control means is configured such that when the abnormality in fixing that the roll rigidity of the vehicle differs depending on the roll direction of the vehicle occurs in the roll rigidity variable means, the steering of the driver Based on the operation amount and the actual turning state amount of the vehicle, a correction amount of the steering operation amount for reducing the deflection of the vehicle due to the sticking abnormality is calculated, and predetermined steering characteristics are calculated based on the driver's steering operation amount. Steering to achieve By calculating the provisional target rudder angle and correcting the provisional target rudder angle with the target rudder angle correction amount derived based on the correction amount of the steering operation amount in order to achieve a predetermined steering characteristic. This is achieved by a vehicle travel control device that calculates a target steering angle of the vehicle and controls the steering wheel steering angle varying means based on the target steering angle .

  As will be described in detail later, when a sticking abnormality occurs in the roll stiffness variable means, the vehicle turning state amount estimated based on the driver's steering operation amount matches the actual turning state amount of the vehicle. Since the magnitude of the deviation between the two turning state quantities indicates a deviation of the vehicle due to the sticking abnormality of the roll stiffness variable means, when the sticking abnormality occurs in the roll stiffness variable means, the steering operation amount of the driver And the degree of deflection of the vehicle due to the abnormal sticking of the roll stiffness variable means can be estimated based on the actual turning state amount of the vehicle, and thus based on the driver's steering operation amount and the actual turning state amount of the vehicle. Thus, it is possible to calculate the correction amount of the steering angle necessary for reducing the deflection of the vehicle.

According to the first aspect of the present invention, when a sticking abnormality in which the roll stiffness of the vehicle differs depending on the roll direction of the vehicle occurs in the roll stiffness varying means, the steering operation amount of the driver and the actual turning state amount of the vehicle are reduced. In order to achieve a predetermined steering characteristic based on the amount of steering operation corrected based on the amount of steering operation corrected to reduce the deflection of the vehicle due to the sticking abnormality The steering wheel target rudder angle is calculated, and the steered wheel rudder angle varying means is controlled based on the target rudder angle . Accordingly, it is possible to calculate the target steering angle of the steered wheel that achieves a predetermined steering characteristic while eliminating the influence of the wheel toe change caused by the abnormal fixation of the roll stiffness varying means, thereby achieving the predetermined steering characteristic. However, since it is possible to reliably reduce the deflection of the vehicle and the unnatural change in the steering reaction force due to the abnormal fixing of the roll stiffness changing means, the abnormal fixing occurs in the roll stiffness control device as compared with the conventional case. The running performance and steering feeling of the vehicle in the situation can be improved.
According to the second aspect of the present invention, when a sticking abnormality in which the roll stiffness of the vehicle differs depending on the roll direction of the vehicle occurs in the roll stiffness varying means, the driver's steering operation amount and the actual turning state amount of the vehicle. Based on the calculation, a correction amount of the steering operation amount for reducing the deflection of the vehicle due to the sticking abnormality is calculated, and the provisional target rudder of the steering wheel for achieving a predetermined steering characteristic based on the driver's steering operation amount The target rudder angle of the steered wheels is calculated by correcting the provisional target rudder angle with the target rudder angle correction amount derived based on the steering operation amount correction amount in order to achieve a predetermined steering characteristic. Then, the steering wheel rudder angle varying means is controlled based on the target rudder angle. Therefore, even with this configuration, it is possible to calculate the target rudder angle of the steered wheel that achieves a predetermined steering characteristic while eliminating the influence of the wheel toe change caused by the abnormal fixation of the roll stiffness varying means, and thereby the predetermined steering While achieving the characteristics, it is possible to reliably reduce the deflection of the vehicle and the unnatural change in the steering reaction force caused by the abnormal fixing of the roll stiffness changing means, so that the abnormal fixing of the roll stiffness control device is less than the conventional one. It is possible to improve the running performance and steering feeling of the vehicle in the situation where it occurs.

According to the present invention, in order to effectively achieve the above-mentioned main problems, in the configuration of the above-described claim 1 or 2 , the steering wheel rudder angle control means is a standard turning based on a driver's steering operation amount. The correction amount of the steering operation amount is calculated based on a deviation between the state amount and the actual turning state amount (configuration of claim 3 ).

According to the configuration of the third aspect , the correction amount of the steering operation amount is calculated based on the deviation between the reference turning state amount based on the driver's steering operation amount and the actual turning state amount. It is possible to reliably and accurately calculate the correction amount of the steering operation amount for reducing the vehicle deflection.

According to the present invention, in order to effectively achieve the above main problem, in the configuration of the first or second aspect , the steering wheel rudder angle control means is configured so that the amount of steering operation by the driver is small. A correction amount of the steering operation amount is calculated based on an actual turning state amount that is equal to or less than a reference value for vehicle straight-running determination and an actual turning state amount is greater than or equal to a reference value for vehicle turning determination. (Structure of claim 4 ).

According to the configuration of the fourth aspect , the magnitude of the driver's steering operation amount is equal to or less than the reference value for determining whether the vehicle is going straight, and the actual magnitude of the turning state is equal to or greater than the reference value for determining whether the vehicle is turning. Since the correction amount of the steering operation amount is calculated based on the actual turning state amount at that time, in order to make the actual turning state amount the turning state amount corresponding to the steering operation amount of the driver, as will be described in detail later. The steering angle correction amount can be reliably and accurately calculated as the steering operation amount correction amount.
According to the present invention, in order to effectively achieve the main problems described above, in the configuration of claim 4, the roll stiffness variable means changes the roll stiffness of the vehicle on the front wheel side. Including a stiffness variable means and a roll stiffness variable means on the rear wheel side for changing the roll stiffness of the vehicle on the rear wheel side, and the steering wheel steering angle control means causes a sticking abnormality in the roll stiffness variable means on the front wheel side. The correction amount of the steering operation amount is calculated when the steering operation amount is set.
According to the fifth aspect of the present invention, even if a sticking abnormality occurs in the roll rigidity variable means on the front wheel side, the vehicle deflection caused by the sticking abnormality of the roll rigidity variable means on the front wheel side while achieving a predetermined steering characteristic. Can be reliably reduced.

According to the present invention, in order to effectively achieve the above main problem, in the configuration of the first or second aspect , the steering wheel rudder angle control means is configured so that the amount of steering operation by the driver is small. The correction amount of the steering operation amount is calculated based on the driver's steering operation amount when the actual turning state amount is equal to or larger than the vehicle turning determination reference value and equal to or less than the vehicle straight traveling determination reference value. (Structure of claim 6 ).

According to the configuration of claim 6 , the magnitude of the steering operation amount of the driver is equal to or greater than the reference value for the vehicle turning determination, and the actual amount of turning state is equal to or less than the reference value for the straight-ahead determination of the vehicle. Since the steering angle correction amount is calculated based on the steering operation amount of the driver at the time, as will be described in detail later, in this case as well, the actual turning state amount corresponds to the steering operation amount of the driver. the correction amount of the steering operation amount as a correction amount of the steering operation amount to the amount can be reliably and accurately calculated.
According to the present invention, in order to effectively achieve the above main problem, in the configuration of the above-mentioned claim 6, the roll stiffness varying means changes the roll stiffness of the vehicle on the front wheel side. Including a stiffness variable means and a rear wheel roll stiffness variable means for changing the roll stiffness of the vehicle on the rear wheel side, and the steering wheel steering angle control means causes a sticking abnormality in the roll stiffness variable means on the rear wheel side. In this case, the correction amount of the steering operation amount is calculated.
According to the configuration of the seventh aspect, even when a sticking abnormality occurs in the roll rigidity variable means on the rear wheel side, the vehicle caused by the sticking abnormality of the roll rigidity variable means on the rear wheel side while achieving a predetermined steering characteristic. Can be reliably reduced.

[Preferred embodiment of problem solving means]
According to one preferred aspect of the present invention, in the structure according to any one of claims 1 to 7 , the roll stiffness changing means changes the roll stiffness of the vehicle by changing the torsional stiffness of the stabilizer. (Preferred embodiment 1).

According to another preferred aspect of the present invention, in the configuration of the above-described fifth aspect, when an abnormality in fixing occurs in the roll rigidity variable means on the front wheel side or the rear wheel side, the other roll rigidity variable means is provided. Is configured to be stopped (preferred aspect 2 ).

According to another preferred aspect of the present invention, in the structure according to any one of the first to seventh aspects or the preferred aspect 1 or 2 , the traveling control device is provided when the vehicle is in a steady traveling state. A steering angle correction amount for reducing the deflection of the vehicle due to the sticking abnormality is calculated based on the driver's steering operation amount and the actual turning state amount of the vehicle (preferred aspect 3 ).

According to the aspect of the present invention, in the any one of the above claims 3 to 7 or the preferred embodiments 1 through 3, the travel control unit norm turning state quantity based on the steering angle and the vehicle speed (Preferred aspect 4 ).

According to another preferred aspect of the present invention, in the configuration according to any one of claims 3 to 7 or preferred aspects 1 to 3 , the travel control device calculates a reference yaw rate based on the steering angle and the vehicle speed. (Preferred embodiment 5 ).

  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 a steering angle varying means for the front wheels to be driven, and is controlled by the electronic control unit 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. And a signal indicating the yaw rate γ of the vehicle detected by the yaw rate sensor 60 are input. The electronic control units 22 and 44 communicate with each other and exchange necessary signals.

  The lateral acceleration sensor 48, the steering angle sensor 56, and the yaw rate sensor 60 detect the lateral acceleration Gy, the steering angle θ, and the yaw rate γ with positive values generated when the vehicle turns to the left, and the rotation angle sensor 58 moves in the left turning direction. The relative rotation angle θre is detected with the case of relative steering of the left and right front wheels as positive.

  The electronic control unit 22 estimates the roll moment acting on the vehicle based on at least the lateral acceleration Gy of the vehicle according to the flowchart shown in FIG. 2, and cancels the roll moment when the magnitude of the roll moment is greater than or equal to the reference value. The target anti-roll moment Mat of the vehicle is calculated so that the anti-roll moment in the direction 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 preferable roll rigidity distribution ratio of the front and rear wheels.

  Thus, the active stabilizer devices 16 and 18, the electronic control device 22, the lateral acceleration sensor 48, etc. function as roll stiffness variable means for increasing or decreasing 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 22 sets a flag Ff indicating that when the front wheel side active stabilizer device 16 is stuck abnormally, and the rear wheel side active stabilizer device 18 is stuck abnormally. If it is, the flag Fr indicating that is set to 1. Signals indicating the flags Ff and Fr are output to the electronic control unit 44.

  It should be noted that the determination of whether or not there is a sticking abnormality in the active stabilizer devices 16 and 18 does not form the gist of the present invention, and may be achieved in any manner known in the art, for example, This may be done by determining whether or not the actuators 20F and 20R operate in response to the control currents for them and have changed corresponding to the actual rotation angles φF and φR.

  Further, the electronic control unit 44 calculates a target steering gear ratio Rgt based on the vehicle speed V according to the flowchart shown in FIG. 3, and when the active stabilizer devices 16 and 18 are normal, the steering indicating the steering operation amount of the driver. Based on the angle θ and the target steering gear ratio Rgt, the target steering angle δft of the front wheels is calculated. The electronic control device 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.

  As shown in FIG. 11A, a sticking abnormality occurs in the active stabilizer device 16 on the front wheel side, and the left and right front wheels 10FL and 10FR are steered by Δδf in the left turning direction with respect to the normal direction by the roll steer. If the steering wheel 24 is in the neutral position, the left and right front wheels 10FL and 10FR are steered by Δδf in the left turning direction with respect to the straight traveling direction of the vehicle, and the vehicle turns left. The yaw rate γ of the vehicle is a positive value.

  Further, the left and right front wheels 10FL and 10FR are acted on by a moment Mf as a reaction force of the turning lateral force to steer those wheels in the right turning direction and return to the straight traveling position of the vehicle. Thus, unnecessary steering torque ΔTs in the same direction as when the vehicle is turned to the left is applied to the steering system.

  Therefore, the active stabilizer devices 16 and 18 are normal, but the actuators 20F and 20R do not operate, and the steering angle θ and the vehicle yaw rate γ when the active stabilizer devices 16 and 18 function as a conventional general stabilizer. However, assuming that the relationship shown in FIG. 11B is obtained at a certain vehicle speed V, the steering angle θ and the vehicle yaw rate γ in the situation where the fixing abnormality has occurred in the active stabilizer device 16 on the front wheel side are: The relationship shown by the solid line in FIG. 11C is obtained at the same vehicle speed. That is, the line indicating the relationship between the steering angle θ and the yaw rate γ of the vehicle shifts in the opposite direction to Δθ along the axis of the steering angle θ by the steering angle Δθ corresponding to the turning angle Δδf of the front wheels by roll steer.

  In addition, a sticking abnormality occurs in the active stabilizer device 16 on the front wheel side, and the steering angle θ and the vehicle in the situation where the left and right front wheels 10FL and 10FR are steered Δδf in the right turn direction with respect to the normal direction by roll steer. The yaw rate γ has the relationship indicated by the phantom line in FIG. 11C at the same vehicle speed.

Therefore, when a sticking abnormality occurs in the active stabilizer device 16 on the front wheel side, the yaw rate γ of the vehicle when the steering angle θ is substantially 0 and the steering torque Ts is the value at the time of turning of the vehicle is Represents an unnecessary vehicle yaw rate Δγ due to roll steer of the front wheels due to an abnormal fixation of the active stabilizer device 16 on the front wheel side, and the steering angle value Δθ corresponding to the unnecessary vehicle yaw rate Δγ is a deviation of the steering angle. This represents the amount (a correction amount of the driver's steering operation amount) .

  Therefore, the electronic control unit 44 determines that the steering angle θ is substantially 0 and the magnitude of the steering torque Ts is a reference for determining turning of the vehicle when the front wheel side active stabilizer device 16 has a sticking abnormality. The steering angle deviation amount Δθ is calculated based on the yaw rate γ as the vehicle turning state amount when the value is equal to or greater than the value.

  Further, as shown in FIG. 12A, a sticking abnormality occurs in the active stabilizer device 18 on the rear wheel side, and the left and right rear wheels 10RL and 10RR are turned leftward (right side) with respect to the normal direction by roll steer. If the steering wheel 24 is in the neutral position and the left and right front wheels 10FL and 10FR are in the straight traveling direction of the vehicle, the vehicle is deflected in the left turn direction. The yaw rate γ is a positive value.

  Further, a lateral turning force acts on the left and right front wheels 10FL and 10FR, and as a reaction force, the wheels are steered in the right turning direction so as to have the same turning angle as that of the rear wheels so as to make the vehicle travel straight ahead. And the unnecessary steering torque ΔTs in the same direction as when turning the vehicle to the left acts on the steering system due to the moment Mf.

  Therefore, although the active stabilizer devices 16 and 18 are normal, the steering angle θ and the vehicle yaw rate γ in the case where the active stabilizer devices 16 and 18 function as a conventional general stabilizer without the actuators 20F and 20R being operated. 12B at a certain vehicle speed V, the steering angle θ and the vehicle yaw rate γ in a situation in which a sticking abnormality has occurred in the active stabilizer device 18 on the rear wheel side. Is the relationship indicated by the solid line in FIG. 12C at the same vehicle speed. That is, the line indicating the relationship between the steering angle θ and the yaw rate γ of the vehicle shifts in the opposite direction to Δθ along the axis of the steering angle θ by the steering angle Δθ corresponding to the steering angle Δδr of the rear wheels by roll steer.

  In addition, a sticking abnormality occurs in the active stabilizer device 18 on the rear wheel side, and the right and left rear wheels 10RL and 10RR are steered by Δδr to the right turning direction (left side) with respect to the normal direction by the roll steer. The steering angle θ in the situation and the yaw rate γ of the vehicle have the relationship indicated by the phantom line in FIG. 12C at the same vehicle speed.

  Further, when the driver steers the left and right front wheels 10FL and 10FR in the right turning direction of the vehicle as shown by the phantom line in FIG. Without making a left turn, in other words, with the yaw rate γ substantially zero, the vehicle travels straight while moving slightly to the right.

Therefore, when a sticking abnormality has occurred in the active stabilizer device 18 on the rear wheel side, the steering angle θ when the steering torque Ts is a value corresponding to the turning of the vehicle and the vehicle is substantially in a straight traveling state. Represents a steering angle deviation amount Δθ (a correction amount of the steering operation amount of the driver) caused by the roll steer of the rear wheel due to the abnormal fixation of the active stabilizer device 18 on the rear wheel side.

  Accordingly, the electronic control unit 44 determines that the magnitude of the steering torque Ts is equal to or greater than the reference value for vehicle turning determination and the yaw rate γ of the vehicle when the rear wheel side active stabilizer device 18 is stuck abnormally. The steering angle θ when the magnitude is equal to or less than the reference value for determining whether the vehicle is going straight is calculated as the steering angle deviation amount Δθ.

  When the electronic control unit 44 calculates the steering angle deviation amount Δθ, the electronic control unit 44 calculates the target steering angle δft of the front wheels based on the steering angle obtained by subtracting and correcting the steering angle θ by the deviation amount Δθ and the target steering gear ratio Rgt. Thus, the steering angle of the front wheels is corrected so as to cancel the influence of the wheel toe change caused by the roll steer, thereby preventing the vehicle from deflecting due to the roll steer while achieving a predetermined steering characteristic.

  Next, the vehicle travel control in the illustrated embodiment 1 will be described with reference to the flowcharts shown in FIGS. 2 and 3 are flow charts showing a roll rigidity control routine and a front wheel steering 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. Repeatedly executed. The same applies to other embodiments described later.

  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, an abnormal sticking to the front wheel side active stabilizer device 16 is detected. 2 is determined. When an affirmative determination is made, the flag Ff is set to 1 in step 220, and then the control by the routine shown in FIG. If yes, go to step 225.

  In step 225, it is determined whether or not a sticking abnormality has occurred in the active stabilizer 18 on the rear wheel side. If an affirmative determination is made, the flag Fr is set to 1 in step 230. Thereafter, when the control by the routine shown in FIG. 2 is completed and a negative determination is made, the flag Ff and Fr are reset to 0 in step 235, and then the process proceeds to step 240.

In step 240, the target roll stiffness distribution ratio Rmf of the front wheels is calculated as a value larger than 0 and smaller than 1 so that it increases as the vehicle speed V increases. In step 245, for example, the magnitude of the lateral acceleration Gy of the vehicle is increased. 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. In step 250, the target anti-roll moment of the front wheels is calculated according to the following equations 1 and 2, respectively. Maft and rear wheel target anti-roll moment Mart are calculated.
Maft = RmfMat (1)
Mart = (1-Rmf) Mat (2)

  In step 255, 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 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 315, it is determined whether or not the flag Fa is 1. That is, it is determined whether or not the calculation of the unnecessary steering torque ΔTs caused by the abnormal fixing of the front wheel side active stabilizer device 16 or the rear wheel side active stabilizer device 18 is completed, and an affirmative determination is made. If YES, the process proceeds to step 365. If a negative determination is made, the process proceeds to step 320.

  In step 320, it is determined whether or not the flag Ff is 1, that is, whether or not a sticking abnormality has occurred in the active stabilizer device 16 on the front wheel side. Proceed to 340, and if an affirmative determination is made, proceed to step 325.

  In step 325, the absolute value of the steering angle θ is equal to or less than the reference value θ1 (positive constant close to 0) for determining the neutral position of the steering angle, and the absolute value of the steering torque Ts is the reference value Ts1 (positive constant). Whether or not the absolute value of the yaw rate γ of the vehicle is greater than or equal to the reference value γ1 (positive constant), that is, the steering torque Ts is determined even though the steering wheel 24 is substantially in the neutral position. It is determined whether or not the vehicle is in a turning state, and when a negative determination is made, the steering angle deviation amount Δθ is set to 0 and the flag Fa is reset to 0 in step 330. Then, the process proceeds to step 365. If an affirmative determination is made, the process proceeds to step 335.

  In step 335, the steering angle deviation amount Δθ is calculated from the map corresponding to the graph shown in FIG. 4 based on the yaw rate γ and the vehicle speed V of the vehicle, and the flag Fa is set to 1. Then, the flow advances to step 365. move on.

  In step 340, it is determined whether or not the flag Fr is 1, that is, whether or not a sticking abnormality has occurred in the active stabilizer device 18 on the rear wheel side, and when a negative determination is made. In step 345, after the steering angle deviation amount Δθ is set to 0, the process proceeds to step 365. If an affirmative determination is made, the process proceeds to step 350.

  In step 350, the absolute value of the steering angle θ is not less than the reference value θ2 (positive constant) for determining the turning position of the steering angle, and the absolute value of the steering torque Ts is not less than the reference value Ts2 (positive constant). In addition, it is determined whether or not the absolute value of the yaw rate γ of the vehicle is equal to or less than a reference value γ2 (a positive constant close to 0) for determining whether the vehicle is going straight, that is, the steering wheel 24 is at the turning position of the vehicle and the steering torque Ts is In spite of the occurrence, it is determined whether or not the vehicle is substantially in a straight traveling state. If a negative determination is made, the steering angle deviation amount Δθ is set to 0 in step 355. After the flag Fa is reset to 0, the routine proceeds to step 365. When an affirmative determination is made, the steering angle deviation amount Δθ is set to the steering angle θ and the flag Fa is set to 1 in step 360. After step 3 Proceed to 65.

In step 365, the target steering gear ratio Rgt is calculated from the map corresponding to the graph shown in FIG. 5 based on the vehicle speed V. In step 370, the steering angle θ, the steering angle deviation amount Δθ, the target steering is calculated. Based on the gear ratio Rgt, the target steering angle δft of the front wheels for achieving a predetermined steering characteristic according to the following formula 3 and eliminating the influence of roll steer is calculated.
δft = (θ−Δθ) / Rgt (3)

  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.

  In step 385, the target relative rotation angle of the turning angle varying device 34 for changing the front wheel rudder angle δf to the target rudder angle δft based on the front wheel target rudder angle δft in a manner known in the art. θret is calculated, and in step 390, the steered angle varying device 34 is controlled so that the relative rotational angle θre of the steered angle varying device 34 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, a negative determination is made in steps 215 and 225, and in step 240, the target roll stiffness distribution ratio Rmf of the front wheels is calculated. In step 245, the target anti-roll moment Mat is calculated based on the lateral acceleration Gy of the vehicle. In step 250, the front anti-roll target Mat for achieving the target anti-roll moment Mat with the target roll stiffness distribution ratio Rmf is calculated. The roll moment Maft and the rear wheel target anti-roll moment Mart are calculated, and in steps 255 and 260, the active stabilizer devices 16 and 18 are controlled so that the target anti-roll moments Maft and Mart are achieved. Rolls are prevented.

  On the other hand, when an abnormality occurs in the front wheel side active stabilizer device 16, an affirmative determination is made in step 215, and a flag Ff is set to 1 in step 220. Accordingly, a negative determination is first made at step 315, and an affirmative determination is made at step 320, whereby a determination at step 325 is made.

  When the steering torque Ts is generated and the vehicle is turning even though the steering wheel 24 is substantially in the neutral position, an affirmative determination is made in step 325 and the vehicle yaw rate γ is determined in step 335. The steering angle deviation amount Δθ is calculated from the map corresponding to the graph shown in FIG. 4 based on the vehicle speed V, and the flag Fa is set to 1.

  Therefore, when an abnormality of the fixing occurs in the active stabilizer device 16 on the front wheel side and the calculation of the steering angle deviation amount Δθ is completed, an affirmative determination is made in step 315, and in FIG. 5 based on the vehicle speed V in FIG. The target steering gear ratio Rgt is calculated from the map corresponding to the graph shown, and the target of the front wheels is calculated based on the steering angle θ and the target steering gear ratio Rgt that are corrected for reduction by the steering angle deviation Δθ in step 370. The steering angle δft is calculated, and in steps 385 and 390, the turning angle varying device 34 is controlled so that the steering angle δf of the front wheels becomes the target steering angle δft.

  Further, although the front wheel side active stabilizer device 16 is normal, if a sticking abnormality occurs in the rear wheel side active stabilizer device 18, a negative determination is made in step 215, and an affirmative determination is made in step 225. In step 230, the flag Fr is set to 1. Therefore, a negative determination is first made in steps 315 and 320, and an affirmative determination is made in step 340, whereby the determination in step 350 is performed.

  When the steering wheel 24 is in the turning position of the vehicle and the steering torque Ts is generated, but when the vehicle is in a substantially straight traveling state, an affirmative determination is made in step 350 and step 360 is performed. Thus, the steering angle deviation amount Δθ is set to the steering angle θ, and the flag Fa is set to 1.

  Accordingly, when a sticking abnormality occurs in the active stabilizer device 18 on the rear wheel side and the calculation of the steering angle deviation amount Δθ is completed, an affirmative determination is made in step 315, and in FIG. The target steering gear ratio Rgt is calculated from the map corresponding to the graph shown in FIG. 6B. Based on the steering angle θ and the target steering gear ratio Rgt that are reduced and corrected by the steering angle deviation Δθ in step 370, the front wheel The target rudder angle δft is calculated, and in steps 385 and 390, the steered angle varying device 34 is controlled so that the rudder angle δf of the front wheels becomes the target rudder angle δft.

  As can be seen from the above description, according to the illustrated first embodiment, when the front wheel side active stabilizer device 16 is abnormally fixed and roll steer is generated on the left and right front wheels 10FL and 10FR, and the rear wheel side In any case where a sticking abnormality occurs in the active stabilizer device 18 and roll steer occurs in the left and right rear wheels 10RL and 10RR, the steering angle deviation amount Δθ caused by roll steer is reliably It can be estimated accurately.

  Further, according to the illustrated embodiment 1, the target steering angle δft of the front wheels is calculated based on the steering angle θ and the target steering gear ratio Rgt that are reduced and corrected by the steering angle deviation amount Δθ. Thus, the steering angle of the front wheels can be corrected so as to cancel the influence of the toe change of the wheels, thereby preventing the vehicle from deflecting due to roll steer while achieving a predetermined steering characteristic.

  In particular, according to the first embodiment shown in the drawing, the target steering angle δft of the front wheels is calculated based on the steering angle θ and the target steering gear ratio Rgt that are reduced and corrected by the steering angle deviation amount Δθ. As in Examples 2 and 4, the provisional target rudder angle δfta of the front wheels for achieving a predetermined steering characteristic is calculated based on the steering angle θ including the steering angle deviation amount Δθ, and the roll is determined from the provisional target rudder angle δfta. Compared with the case where the target rudder angle δft of the front wheels is calculated by subtracting the correction amount (Δθ / Rgt) of the target rudder angle of the front wheels to eliminate the influence of the steering, the deviation Δθ of the steering angle is It can be calculated efficiently.

  FIG. 7 is a flowchart showing a control routine for the front wheel steering angle in the second embodiment of the vehicle travel control apparatus according to the present invention, which is configured as a modification of the first embodiment. In FIG. 7, steps corresponding to the steps shown in FIG. 3 are given the same step numbers as the step numbers given in FIG. 3.

  When calculating the steering angle deviation amount Δθ, the electronic control unit 44 according to the second embodiment calculates the target steering gear ratio Rgt from the map corresponding to the graph shown in FIG. Based on the target steering gear ratio Rgt, the provisional target steering angle δfta of the front wheels is calculated, and the correction amount based on the steering angle deviation Δθ from the provisional target steering angle δfta, that is, the steering angle deviation Δθ is used as the target steering gear ratio Rgt. By subtracting the divided value, the target steering angle δft of the front wheels is calculated, and the steering angle varying device 34 is controlled so that the steering angle δf of the front wheels becomes the target steering angle δft.

As shown in FIG. 7, in the front wheel steering angle control routine of the second embodiment, steps 310 to 365, 385, and 390 are executed in the same manner as in the first embodiment. In step 380 executed next to step 365, the provisional target steering angle δfta of the front wheels for achieving a predetermined steering characteristic is calculated according to the following equation 4 based on the steering angle θ and the target steering gear ratio Rgt. The
δfta = θ / Rgt (4)

In step 380, a predetermined steering characteristic is achieved according to the following equation 5 based on the provisional target steering angle δfta, the steering angle deviation Δθ, and the target steering gear ratio Rgt, and the front wheel for eliminating the influence of roll steer A target rudder angle δft is calculated.
δft = δfta−Δθ / Rgt (5)

  Thus, according to the illustrated second embodiment, unnecessary steering torque caused by roll steer is produced regardless of whether the front wheel side active stabilizer device 16 or the rear wheel side active stabilizer device 18 is stuck abnormally. ΔTs can be reliably and accurately estimated, and the provisional target steering angle δfta of the front wheels for achieving a predetermined steering characteristic is calculated based on the steering angle θ including the steering angle deviation amount Δθ, and the provisional target Since the target steering angle δft of the front wheels is calculated by subtracting the correction amount (Δθ / Rgt) of the target steering angle of the front wheels for eliminating the influence of roll steer from the steering angle δfta, the target steering angle δft of the front wheels is calculated. As in the case, the steering angle of the front wheels can be corrected so as to offset the influence of the wheel toe change caused by roll steer, thereby achieving a predetermined steering characteristic while the vehicle steered by roll steer It is possible to prevent the direction.

  In particular, according to the first and second embodiments shown in the drawing, it is discriminated whether a sticking abnormality has occurred in the active stabilizer device 16 on the front wheel side or a sticking abnormality has occurred in the active stabilizer device 18 on the rear wheel side, Since the steering angle deviation amount Δθ is calculated when the vehicle is in an optimum traveling state depending on which of the active stabilizer devices on the front wheel side or the rear wheel side the sticking abnormality occurs, the sticking abnormality is detected on the front wheels. The steering angle deviation amount Δθ can be calculated more accurately than when the steering angle deviation amount Δθ is calculated in the same manner regardless of the active stabilizer device on the side or rear wheel side. can do.

  Further, according to the first and second embodiments shown in the figure, when a sticking abnormality has occurred in the active stabilizer device 16 on the front wheel side, the steering wheel 24 is substantially in the neutral position in step 325, When it is determined that the steering torque Ts is generated and the vehicle is in a turning state, the steering angle deviation amount Δθ is calculated, and when there is a sticking abnormality in the rear wheel side active stabilizer device 18, the process proceeds to step 350. When the steering wheel 24 is in the turning position of the vehicle and the steering torque Ts is generated, the steering angle deviation amount Δθ is calculated when it is determined that the vehicle is substantially in the straight traveling state. Therefore, the steering angle deviation amount Δθ can be calculated more accurately than when the steering angle deviation amount Δθ is calculated when the vehicle is in another traveling state. .

  Further, according to the first and second embodiments shown in the drawings, either a case where a sticking abnormality occurs in the front wheel side active stabilizer device 16 or a case where a sticking abnormality occurs in the rear wheel side active stabilizer device 18 occurs. In addition, once the steering angle deviation amount Δθ is calculated in step 335 or 360, the flag Fa is set to 1, and an affirmative determination is made in step 315, whereby steps 325 to 335 or step are performed. Since steps 365 and after are executed without executing 350 to 360, the control for correcting the steering angle of the front wheels can be easily executed as compared with the case where the steering angle deviation amount Δθ is calculated every time. .

  Further, according to the first and second embodiments shown in the drawings, in steps 325 and 350, it is determined whether or not the vehicle is in a specific traveling state in consideration of the steering torque Ts. Therefore, the steering torque Ts is considered. Compared with the case where it is determined whether or not the vehicle is in a specific traveling state based only on the steering angle θ and the vehicle yaw rate γ, the vehicle is more suitable for calculating the steering angle deviation amount Δθ. It is possible to appropriately determine whether or not the vehicle is in a specific traveling state.

  Further, according to the first and second embodiments shown in the figure, when there is a sticking abnormality in the active stabilizer device 16 on the front wheel side, the graph shown in FIG. 4 based on the yaw rate γ and the vehicle speed V of the vehicle in step 335. When the steering angle deviation amount Δθ is calculated from the map corresponding to, and when there is a sticking abnormality in the active stabilizer device 18 on the rear wheel side, the steering angle deviation amount Δθ is changed to the steering angle θ in step 360. Therefore, the standard yaw rate γ as the standard turning state quantity is calculated based on the steering angle θ, for example, as in Examples 3 and 4 to be described later, and the deviation Δγ between the standard yaw rate γ and the actual yaw rate γ is calculated. Compared with the case where the steering angle deviation amount Δθ is calculated based on the yaw rate deviation Δγ, the steering angle deviation amount Δθ can be calculated more efficiently.

  FIG. 8 shows the control of the front wheel steering angle in the third embodiment of the vehicle travel control apparatus according to 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. It is a flowchart which shows a routine.

  As described above, the line indicating the relationship between the steering angle θ and the yaw rate γ of the vehicle in the situation where the front wheel side active stabilizer device 16 is stuck abnormally, and the rear wheel side active stabilizer device 18 is stuck abnormally. The line indicating the relationship between the steering angle θ and the vehicle yaw rate γ in the situation corresponds to the steering angle Δδf of the front wheel by roll steering with respect to the position when the active stabilizer devices 16 and 18 function as normal stabilizers, respectively. The steering angle is shifted in the opposite direction to Δθ along the axis of the steering angle θ corresponding to the steering angle Δθ corresponding to the steering angle Δθ and the steering angle Δδf of the front wheel accompanying the steering of the rear wheel by roll steer.

  In a situation where the active stabilizer devices 16 and 18 function as normal stabilizers, the magnitude of the yaw rate γ of the vehicle generated by turning the front wheels without turning the rear wheels, and the rear wheels The magnitude of the yaw rate γ of the vehicle that is generated when the front wheels are steered to cancel the turning motion of the vehicle due to the turning is large in the steering angle of the front wheels as shown in FIG. The larger the vehicle speed is, the larger the vehicle speed is, and the lower the vehicle speed V is, the smaller the vehicle speed is.

  Therefore, as shown in FIG. 9B, a line indicating the relationship between the steering angle θ and the yaw rate γ of the vehicle is specified based on the vehicle speed V, and the vehicle speed V and the steering are determined based on the specified line and the steering angle θ. The yaw rate γ corresponding to the angle θ can be calculated as the reference yaw rate γb, and the deviation Δγ between the reference yaw rate γb and the yaw rate γ detected by the yaw rate sensor 60 represents an unnecessary yaw rate caused by the wheel roll steer. . Further, there is a relationship as shown in FIG. 9C between the yaw rate deviation Δγ, the vehicle speed V, and the steering angle deviation amount Δθ.

  Therefore, even when the vehicle is in a specific driving state as in the first and second embodiments described above, if the vehicle is in a steady driving state, the yaw rate deviation Δγ and the vehicle speed V A line indicating the relationship of the steering angle deviation amount Δθ can be identified, and the steering angle deviation amount Δθ can be calculated based on the identified line and the yaw rate deviation Δγ.

  The electronic control unit 44 according to the third embodiment pays attention to the above points, and when the fixing abnormality occurs in the active stabilizer device 16 on the front wheel side or the active stabilizer device 18 on the rear wheel side, the vehicle is stationary. A line indicating the relationship between the yaw rate deviation Δγ and the steering angle deviation amount Δθ is identified based on the vehicle speed V when the vehicle is in a running state, and the steering angle deviation amount Δθ is calculated based on the identified line and the yaw rate deviation Δγ. To do.

  Further, the electronic control unit 44 of the third embodiment calculates the target steering angle from the map corresponding to the graph shown in FIG. The gear ratio Rgt is calculated, the target steering angle δft of the front wheels is calculated based on the steering angle θ corrected by the steering angle deviation amount Δθ and the target steering gear ratio Rgt, and the steering angle δf of the front wheels is calculated as the target steering angle. The turning angle varying device 34 is controlled so as to be δft.

  As shown in FIG. 8, in the front wheel steering angle control routine of the third embodiment, steps 810 to 820, 825, 830, 840, and 855 to 880 are steps in the above-described first embodiment. It is executed in the same manner as 310-320, 340, 345, 355, 365-390.

  If an affirmative determination is made in step 820 or 825, that is, if a sticking abnormality has occurred in the active stabilizer device 16 on the front wheel side or the active stabilizer device 18 on the rear wheel side, the vehicle speed V is determined in step 835. Is equal to or greater than the vehicle travel determination reference value Vo (positive constant), and the absolute value of the longitudinal acceleration Vd of the vehicle, which is calculated as a time differential value of the vehicle speed V, for example, is a steady vehicle speed determination reference value Vdo (a positive value close to 0). Or the absolute value of the steering angular velocity θd calculated as a time differential value of the steering angle θ is equal to or less than a reference value θdo (a positive constant close to 0) for steady turning determination, that is, It is determined whether or not the vehicle is in a steady running state. If a negative determination is made, the process proceeds to step 840, and if an affirmative determination is made, the process proceeds to step 845.

  In step 845, a map corresponding to the graph shown in FIG. 9A is specified based on the vehicle speed V, and shown in FIG. 9B from the specified map based on the steering angle θ. As described above, the yaw rate γ corresponding to the vehicle speed V and the steering angle θ is calculated as the standard yaw rate γb.

  In step 850, the yaw rate deviation Δγ is calculated as the deviation between the reference yaw rate γb and the yaw rate γ detected by the yaw rate sensor 60, and a map corresponding to the graph shown in FIG. The steering angle deviation amount Δθ is calculated from the map specified based on the specified yaw rate deviation Δγ, and after the flag Fa is set to 1, the routine proceeds to step 855.

  Thus, according to the third embodiment shown in the drawing, when there is a sticking abnormality in the active stabilizer device 16 on the front wheel side or the active stabilizer device 18 on the rear wheel side, the vehicle speed when the vehicle is in a steady running state. The reference yaw rate γb is calculated based on V and the steering angle θ, and the deviation Δθ between the reference yaw rate γb and the actual yaw rate γ and the vehicle speed V are calculated. The steering angle deviation amount Δθ can be reliably and accurately estimated, and the steering angle of the front wheels can be offset so as to cancel the influence of the wheel toe change caused by roll steer, as in the first and second embodiments. Thus, it is possible to prevent the vehicle from deflecting due to roll steer while achieving a predetermined steering characteristic.

  In particular, according to the third embodiment shown in the drawing, as in the case of the first embodiment described above, the target steering angle δft of the front wheels is based on the steering angle θ corrected by the steering angle deviation amount Δθ and the target steering gear ratio Rgt. Therefore, for example, as in the case of the second embodiment described above and the fourth embodiment described later, a provisional target for the front wheels for achieving a predetermined steering characteristic based on the steering angle θ including the steering angle deviation amount Δθ. The steering angle δfta is calculated, and the target steering angle δft of the front wheels is calculated by subtracting the correction amount (Δθ / Rgt) of the target steering angle of the front wheels for eliminating the influence of roll steer from the provisional target steering angle δfta. As compared with the case, the steering angle deviation amount Δθ can be calculated efficiently.

  FIG. 10 is a flowchart showing a control routine for the front wheel steering angle in the fourth embodiment of the vehicle travel control apparatus according to the present invention, which is configured as a modification of the second embodiment. In FIG. 10, steps corresponding to the steps shown in FIG. 8 are assigned the same step numbers as those shown in FIG.

  As in the case of the above-described third embodiment, the electronic control device 44 of the fourth embodiment is used when the front wheel side active stabilizer device 16 or the rear wheel side active stabilizer device 18 is stuck abnormally. A line indicating the relationship between the yaw rate deviation Δγ and the steering angle deviation amount Δθ is identified based on the vehicle speed V when the vehicle is in a steady running state, and the steering angle deviation amount is identified based on the identified line and the yaw rate deviation Δγ. Δθ is calculated.

  Similarly to the second embodiment, the electronic control unit 44 of the fourth embodiment calculates the target steering angle from the map corresponding to the graph shown in FIG. The gear ratio Rgt is calculated, the front target wheel target steering angle δfta is calculated based on the steering angle θ and the target steering gear ratio Rgt, and the correction amount based on the steering angle deviation amount Δθ from the temporary target steering angle δfta, that is, the steering angle. By subtracting a value obtained by dividing the deviation amount Δθ by the target steering gear ratio Rgt, the target steering angle δft of the front wheels is calculated, and the steering angle varying device 34 so that the steering angle δf of the front wheels becomes the target steering angle δft. To control.

  As shown in FIG. 10, in the front wheel steering angle control routine of the fourth embodiment, steps 810 to 855, 875, and 880 are respectively steps 810 to 855, 875, and the steps of the third embodiment. It is executed in the same way as 880. Steps 865 and 870 executed after step 855 are executed in the same manner as steps 375 and 880 in the second embodiment.

  Thus, according to the fourth embodiment shown in the figure, as in the case of the above-described third embodiment, when there is a sticking abnormality in the active stabilizer device 16 on the front wheel side or the active stabilizer device 18 on the rear wheel side, the vehicle is The reference yaw rate γb is calculated based on the vehicle speed V and the steering angle θ when the vehicle is in a steady running state, and the deviation Δθ between the reference yaw rate γb and the actual yaw rate γ and the steering speed deviation Δθ based on the vehicle speed V is calculated. Since the calculation is performed, it is possible to reliably and accurately estimate the steering angle deviation amount Δθ caused by roll steer, and, as in the first to third embodiments, the wheel toe change caused by roll steer. Thus, the steering angle of the front wheels can be corrected so as to cancel the influence of the vehicle, thereby preventing the vehicle from deflecting due to roll steer while achieving a predetermined steering characteristic.

  In particular, according to the above-described third and fourth embodiments, even when the vehicle is in a specific traveling state as in the first and second embodiments described above, the traveling state of the vehicle may be a steady traveling state. For example, since the steering angle deviation amount Δθ can be calculated based on the vehicle speed V, the steering angle θ, and the yaw rate γ, a sticking abnormality has occurred in the active stabilizer device 16 on the front wheel side or the active stabilizer device 18 on the rear wheel side. In this case, the steering angle deviation amount Δθ can be calculated earlier than in the case of the above-described first and second embodiments, so that prevention of vehicle deflection due to roll steer can be achieved earlier.

  Further, generally, when a sticking abnormality occurs in the active stabilizer device 16 on the front wheel side or the active stabilizer device 18 on the rear wheel side and a wheel toe change due to roll steer occurs, the driver deflects the wheel in the toe change direction. The vehicle must be driven against this, and unnecessary steering torque is generated. Therefore, an unnatural steering feeling in which the steering reaction force varies depending on the turning direction of the vehicle cannot be avoided. When trying to drive straight, the steering wheel must be held against a high steering reaction force.

  According to each of the above-described embodiments, the steering angle of the front wheels is controlled so as to reduce the influence of the wheel toe change caused by the roll steer, so that unnecessary steering torque can be reduced, and thereby the driver The unnatural change in the steering reaction force felt by the engine can be reduced, thereby improving the steering feeling as compared with the prior art and reducing the holding torque.

  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, the vehicle turning state amount is the vehicle yaw rate γ, but the vehicle turning state amount is, for example, a vehicle lateral acceleration or a value obtained by dividing the vehicle lateral acceleration by the vehicle speed V. It may be.

  In each of the above-described embodiments, once the steering angle deviation amount Δθ is calculated, the steering angle deviation amount Δθ is not updated. However, the flag Fa is omitted, and the steering angle deviation amount is calculated. The correction may be made so that Δθ is calculated every time, and when a predetermined time elapses from the time when the steering angle deviation Δθ is calculated or updated, the process proceeds to step 320, whereby the steering angle deviation Δθ is updated. It may be modified so that.

Further, in each of the above-described embodiments, the turning angle varying device 34 rotates the lower steering shaft 36 relative to the upper steering shaft 32 so that the left and right front wheels 10FL do not depend on the steering operation of the driver. And 10FR are automatically steered, but as long as the steered wheels can be steered and the steer angle can be controlled independently of the driver's steering operation, for example, a type of steer that expands and contracts the tie rods 30L and 30R. Any configuration known in the art, such as a variable angle device, may be used.
In each of the above-described embodiments, the steered wheel is the front wheel, and the electronic control unit 44 adjusts the steered angle of the front wheel by the steered angle varying device 34 so as to cancel the influence of the wheel toe change caused by the roll steer. When the vehicle is equipped with a rear wheel steering device, the steering angle of the rear wheel is corrected and controlled so that the effect of wheel toe change caused by roll steering is offset or reduced. May be modified.

  In the first and second embodiments described above, the reference value Ts1 in the determination in step 325 and the reference value Ts2 in the determination in step 350 are positive constants. Even if the turning angle of the wheel is constant, the magnitude of the steering torque actually generated is smaller as the vehicle speed V is lower and larger as the vehicle speed V is higher. Therefore, these reference values are larger as the vehicle speed V is higher. It may be modified so as to be variably set according to the vehicle speed V so as to decrease as V decreases.

  In the first and second embodiments described above, it is determined whether or not the vehicle is in a specific traveling state in consideration of the steering torque Ts in steps 325 and 350. The condition of the steering torque Ts may be omitted.

In the first and second embodiments described above, when an affirmative determination is made in step 325, the map corresponding to the graph shown in FIG. 4 is used based on the yaw rate γ of the vehicle in step 335. The steering angle deviation amount Δθ is calculated. Based on the absolute value of the vehicle yaw rate γ, the steering angle deviation amount Δθb is calculated from the map corresponding to the graph shown in FIG. The steering angle deviation amount Δθ may be corrected so as to be calculated according to the following equation 6 with sign γ as the sign of the vehicle yaw rate γ.
Δθ = signγ ・ Δθb (6)

  In the above-described first and second embodiments, when there is a sticking abnormality in the active stabilizer device 16 on the front wheel side, the determination in step 325 is performed, and a sticking abnormality occurs in the active stabilizer device 18 on the rear wheel side. In step 350, the determination in step 350 is performed. However, when a sticking abnormality has occurred in the active stabilizer device on the front wheel side or the rear wheel side, determination in step 325 is first performed. In this case, it may be modified so as to proceed to step 350 when a negative determination is made.

  In the first and second embodiments described above, it is not determined whether or not the vehicle is in a steady state, but the vehicle is in a steady state. It may be modified so that the determination in step 325 or 350 is performed only when the vehicle is in a steady traveling state.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram illustrating 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 showing a control routine for a front wheel steering angle in the first embodiment. It is a graph which shows the relationship between the yaw rate (gamma) and vehicle speed V of a vehicle, and deviation | shift amount (DELTA) (theta) of a steering angle. It is a graph which shows the relationship between the vehicle speed V and the target steering gear ratio Rgt. 6 is a graph showing a relationship between an absolute value of a yaw rate γ of a vehicle and a vehicle speed V and a steering angle deviation amount Δθ. FIG. 6 shows a routine for controlling the front wheel steering angle in the second embodiment of the vehicle travel control apparatus according to 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. It is a flowchart. FIG. 6 shows a control routine for the front wheel steering angle in the third embodiment of the vehicle travel control apparatus according to 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. It is a flowchart. A graph (A) showing the relationship between the steering angle θ and the vehicle speed V and the yaw rate γ of the vehicle, an explanatory diagram (B) showing the point of calculating the reference yaw rate γb based on the steering angle θ, the yaw rate deviation Δγ and the vehicle speed V 6 is a graph (C) showing the relationship between the steering angle deviation amount Δθ. 7 shows a routine for controlling a front wheel steering angle in a fourth embodiment of a vehicle traveling control apparatus according to 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. It is a flowchart. Explanatory drawing (A) which shows the situation where sticking abnormality has occurred in the active stabilizer device on the front wheel side and roll steer has occurred on the front wheel, the steering angle when the active stabilizer devices on the front wheel side and the rear wheel side are normal A graph (B) showing the relationship between θ and the yaw rate γ of the vehicle, the steering angle θ and the yaw rate of the vehicle when the front wheel side active stabilizer device is stuck abnormally and roll steer is generated on the front wheels It is a graph (C) which shows the relationship between (gamma). Explanatory drawing (A) which shows the situation where the sticking abnormality has occurred in the active stabilizer device on the rear wheel side and the roll steer is generated in the rear wheel, in the case where the active stabilizer devices on the front wheel side and the rear wheel side are normal Graph (B) showing the relationship between the steering angle θ and the yaw rate γ of the vehicle, the steering angle θ when the rear wheel side active stabilizer device has a sticking abnormality and the rear wheel has roll steer 6 is a graph (C) showing the relationship between the vehicle and the yaw rate γ of the vehicle.

Explanation of symbols

16, 18 Active stabilizer device 20F, 20R Actuator 22 Electronic control device 26 Power steering 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 60 Yaw rate sensor

Claims (7)

Steering wheel rudder angle varying means capable of changing the rudder angle of the steered wheel regardless of the driver's steering, and steering wheel rudder angle for controlling the steered wheel rudder angle varying means so that the rudder angle of the steered wheel becomes the target rudder angle. In the vehicle travel control device having the control means and the roll stiffness varying means for changing the roll stiffness of the vehicle, the steering wheel steering angle control means has the fixing abnormality in which the roll stiffness of the vehicle varies depending on the roll direction of the vehicle. When this occurs in the roll stiffness variable means, the correction amount of the steering operation amount for reducing the deflection of the vehicle due to the sticking abnormality is calculated based on the steering operation amount of the driver and the actual turning state amount of the vehicle. And calculating a target rudder angle of a steered wheel for achieving a predetermined steering characteristic based on the steering operation amount corrected by the correction amount of the steering operation amount, and based on the target rudder angle, the steering wheel rudder To control the angle variable means Travel control device for a vehicle according to symptoms. Steering wheel rudder angle varying means capable of changing the rudder angle of the steered wheel regardless of the driver's steering, and steering wheel rudder angle for controlling the steered wheel rudder angle varying means so that the rudder angle of the steered wheel becomes the target rudder angle In the vehicle travel control device having the control means and the roll stiffness varying means for changing the roll stiffness of the vehicle, the steering wheel steering angle control means has the fixing abnormality in which the roll stiffness of the vehicle varies depending on the roll direction of the vehicle. When this occurs in the roll stiffness variable means, the correction amount of the steering operation amount for reducing the deflection of the vehicle due to the sticking abnormality is calculated based on the steering operation amount of the driver and the actual turning state amount of the vehicle. And calculating a provisional target rudder angle of the steered wheel for achieving a predetermined steering characteristic based on the driver's steering operation amount, and based on the correction amount of the steering operation amount to achieve the predetermined steering characteristic. Corrected target rudder angle The provisional target steering angle target steering angle of the steering wheel is calculated by modifying a running control device for a vehicle and controlling the steering wheel steering angle varying unit based on the target steering angle at. The steering wheel steering angle control means calculates a correction amount of the steering operation amount based on a deviation between a reference turning state amount based on a driver's steering operation amount and an actual turning state amount. Or the vehicle travel control device according to 2; The steering wheel rudder angle control means is configured such that the magnitude of the driver's steering operation amount is equal to or less than a reference value for determining whether the vehicle is going straight and the actual amount of turning state is equal to or greater than the reference value for determining whether the vehicle is turning. actual traveling control apparatus for a vehicle according to claim 1 or 2, characterized in that for calculating the correction amount of the steering operation amount based on the turning state quantity. The roll stiffness varying means includes a front wheel side roll stiffness varying means for changing the roll stiffness of the front wheel side vehicle and a rear wheel side roll stiffness varying means for changing the roll stiffness of the rear wheel side vehicle. 5. The vehicle travel control according to claim 4, wherein the wheel steering angle control means calculates a correction amount of the steering operation amount when a sticking abnormality has occurred in the roll rigidity variable means on the front wheel side. apparatus. The steering wheel rudder angle control means is configured such that the magnitude of the driver's steering operation amount is greater than or equal to a reference value for determining turning of the vehicle and the actual amount of turning state is equal to or less than the reference value for determining whether the vehicle is going straight. running control apparatus for a vehicle according to claim 1 or 2, characterized in that for calculating the correction amount of the steering operation amount based on the steering operation amount by the driver. The roll stiffness varying means includes a front wheel side roll stiffness varying means for changing the roll stiffness of the front wheel side vehicle and a rear wheel side roll stiffness varying means for changing the roll stiffness of the rear wheel side vehicle. 7. The vehicle travel according to claim 6, wherein the wheel steering angle control means calculates a correction amount of the steering operation amount when a sticking abnormality occurs in the roll stiffness variable means on the rear wheel side. Control device.

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