JP4992331B2 - Vehicle slip control device - Google Patents

Description

  The present invention relates to a technique for converging slip of a driving wheel of a vehicle in a vehicle slip control device.

As this type of slip control device, Patent Document 1 proposes a device that restricts the torque output from the motor to the drive wheel when the drive wheel idles due to the torque output from the motor. In this device, a slip control technique is known that limits the torque of a motor by referring to a map associated with the torque so that the torque upper limit value decreases as the angular acceleration increases when idling occurs in the drive wheels.
JP 2004-96825 A

  This conventional slip control technique reduces the angular acceleration of the drive wheel by predetermining a torque upper limit value in accordance with the angular acceleration of the drive wheel. In this configuration, since the torque that can be transmitted to the road surface by the drive wheels is not taken into consideration, the maximum value of the torque that can be transmitted to the road surface by the drive wheels cannot be the upper limit value of the torque.

  Therefore, when the slip is accelerated again after convergence, the slip may occur or it may be difficult to quickly converge the slip.

  An object of the present invention is to quickly converge a slip of a drive wheel regardless of a change in a vehicle state when the drive wheel is in a slip state.

The vehicle slip control device of the present invention includes a driving source for driving wheels, a driving force control means for controlling the driving force of the driving source based on a driving force command value, and a first driving force based on a driver's request. a first driving force command value calculating means for calculating a command value, and a second driving force command value calculating means for calculating a second driving force command value based on the driving force of the driving source and the angular acceleration of the drive wheel, the drive Slip amount calculating means for calculating the slip amount of the wheel; and correcting means for correcting the second driving force command value by calculating a driving force correction value for converging the slip amount calculated by the slip amount calculating means to the target slip amount; , Delay means for adding the driving force command value calculated by the second driving force command value calculating means as a value delayed from the correction value calculated by the correcting means, and the drive wheels are in a slip state Sometimes, to the driving force control means Switching the driving force command value from the first driving force command value to the second driving force command value.

According to the present invention, a drive force and the angular acceleration of the wheel drive when slippage of the driving wheels, and calculates the driving force command value. Therefore, the driving force command value is calculated to be the maximum value of torque that can be transmitted to the road surface by the driving wheels. Therefore, even if the friction coefficient of the road surface and the wheel load change, it is possible to appropriately command the driving torque of the driving wheel, the slip can be quickly converged, and the slip is generated at the time of reacceleration after the slip convergence. Can also be avoided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a system configuration diagram of a vehicle slip control apparatus according to the present invention. The vehicle of the present embodiment is an electric vehicle that travels by driving a rear wheel.

  The motors 5 and 6 are AC machines capable of power running and regenerative operation, such as a three-phase synchronous motor and a three-phase induction motor. The motor 5 drives the left rear wheel 3 and the motor 6 drives the right rear wheel 4. Each of the motors 5 and 6 has a current sensor built therein, and transmits the magnitude of the current flowing through each of the motors 5 and 6 to the controller 30.

  The inverters 7 and 8 convert the direct current supplied from the battery 9 into alternating current and supply the alternating current to the motors 5 and 6, respectively, and convert the alternating current generated by the motors 5 and 6 into direct current to the battery 9. Charge. The battery 9 is, for example, a nickel metal hydride battery or a lithium ion battery.

  The wheel speed sensors 10 to 13 detect the rotational speeds ω1 to ω4 of the wheels 1 to 4 and transmit them to the controller 30. Here, the radius of rotation of each of the wheels 1 to 4 is the same as R. The rear wheels 3 and 4 and the motors 5 and 6 are directly connected with a reduction ratio of 1, that is, directly. Each of the wheels 1 to 4 has the same tire characteristics, and when the wheel load, the side slip angle, and the road surface friction coefficient are equal, the relationship between the driving force and the tire lateral force is the same.

  The steering angles of the front wheels 1 and 2 are adjusted by the steering of the steering wheel 14 by the driver. Note that the change amount of the steering angle of the front wheels 1 and 2 is set to be, for example, 1/16 of the change amount of the steering angle of the steering wheel 14. The steering angle sensors 15 to 18 detect the steering angles δ1 to δ4 of the wheels 1 to 4 and transmit them to the controller 30. Each of the wheels 1 to 4 is equipped with a mechanical brake, and can be braked according to a command from the controller 30.

  The acceleration sensor 19 is attached to the position of the center of gravity of the vehicle, detects the longitudinal acceleration αx and the lateral acceleration αy of the vehicle, and the yaw rate sensor 20 detects the yaw rate γ and transmits it to the controller 5. The steering angle sensor 21 detects the steering angle θ of the steering wheel 14 by the driver, the accelerator stroke sensor 22 detects the depression amount AP of the accelerator pedal 23, and the brake stroke sensor 24 detects the depression amount BP of the brake pedal 25. To the controller 30. The controller 30 controls the torque of the motors 5 and 6 based on the received signal.

  Next, the control performed by the controller 30 will be described with reference to the flowchart of FIG. This control is repeatedly executed every predetermined time (for example, 10 ms).

  In step S1, the rotational speeds ω1 to ω4, the steering angles δ1 to δ4, the vehicle longitudinal acceleration αx, the lateral acceleration αy, the yaw rate γ, and the steering angle θ of the steering wheel are read. The longitudinal acceleration αx of the vehicle is positive in the direction in which the vehicle accelerates forward, the lateral acceleration αy is positive in the direction from the center of gravity of the vehicle toward the turning center when the vehicle is turning left, and the yaw rate γ is vertically upward of the vehicle. A counterclockwise direction is positive when entangled.

  In step S2, the vehicle speed V is calculated based on the rotational speeds ω1 to ω4 of the wheels 1 to 4. Here, the speeds V1 to V4 of the wheels 1 to 4 are calculated by multiplying the rotational speeds ω1 to ω4 of the wheels by the wheel radius R, respectively. The vehicle speed V is calculated based on the following equation (1) using the speeds V1 and V2 of the front wheels 1 and 2. V and V1 to V4 are positive in the vehicle forward direction.

  In step S3 (slip amount calculation means), the slip amounts λ3 and λ4 of the rear wheels 3 and 4 as drive wheels are calculated based on the following equations (2) and (3).

  In step S4, the target value tF of the force applied in the longitudinal direction of the vehicle is calculated. The target value tF is calculated based on the following equation (4).

  Here, tFa is a driving force calculated with reference to the map of FIG. 3 based on the depression amount AP and the vehicle speed V of the accelerator pedal 23, and tFb is a table of FIG. 4 based on the depression amount BP of the brake pedal 25. Is a braking force calculated with reference to FIG. Note that tF, tFa, and tFb are positive in the direction in which the vehicle is accelerated forward.

  In step S5, a target value ΔF of the driving force difference between the left and right driving wheels 3 and 4 is calculated. The target value ΔF is calculated based on the vehicle speed V and the steering angle θ of the steering 14 with reference to the map of FIG.

  In step S6 (first driving force command value calculation means), the first driving force command values Fx3 and Fx4 of the rear wheels 3 and 4 are determined based on the driver's request based on the following equations (5) and (6). The driving force command value obtained is calculated. The first driving force command values Fx3 and Fx4 are positive for the force acting in the direction of moving the vehicle forward.

  In step S7 (second driving force command value calculating means), second driving force command values Ff3 and Ff4, which are driving forces corresponding to the road surface reaction force, are calculated. The second driving force command values Ff3 and Ff4 are calculated based on the following equations (7) and (8).

  Here, Tm5 and Tm6 are the torques of the motors 5 and 6, respectively, and are calculated based on detection values of current sensors built in the motors 5 and 6, respectively. Ir is the inertia of the rear wheel, and dω3 / dt and dω4 / dt are differential values of the rotational speeds ω3 and ω4 of the rear wheels 3 and 4, respectively, and are based on the following equations (9) and (10). Is calculated.

  Here, ω3 (k−1) and ω4 (k−1) are the rotational speeds ω3 and ω4 in the previous process. Tsamp is a calculation cycle.

  As described above, the vehicle is transmitted to the road surface without slipping from the relationship between the current motor torque of the vehicle calculated based on the detection value of the current sensor built in the motors 5 and 6 and the angular acceleration of the rear wheels. Since a possible driving force (corresponding to a road surface reaction force) is obtained, an appropriate driving force command value corresponding to a change in vehicle state (a change in wheel load and road surface friction) can be generated. Further, since the second driving force command values Ff3 and Ff4 are calculated not by map search but by calculation, the ROM of the controller 30 can be reduced to reduce the manufacturing cost.

  In step S8 (correction means), driving force correction amounts Fb3 and Fb4 which are correction amounts of the driving force of the driving wheels 3 and 4 for converging the slip amounts λ3 and λ4 of the rear wheels 3 and 4 to the target slip amount λ ′. Is calculated based on the following equations (11) and (12). The target slip amount λ ′ is the slip amounts λ3 and λ4 when the road surface reaction force becomes maximum, that is, the slip amounts λ3 and λ4 when the frictional force between the drive wheels 3 and 4 and the road surface becomes maximum.

  Here, P is a gain, for example, 20 and the target slip amount λ ′ is, for example, 0.15.

  The driving force correction amounts Fb3 and Fb4 may be calculated using sliding mode control, PID control, PI control, and the like.

  In step S9, the corrected second driving force command values Fs3 and Fs4 are calculated based on the following equations (13) and (14).

  In step S10 (switching means), the first driving force command values Fx3 and Fx4 are compared with the corrected second driving force command values Fs3 and Fs4, and the smaller value is set as the control driving force F3 and F4. This is because the corrected second driving force command values Fs3 and Fs4 are always calculated larger than the first driving force command values Fx3 and Fx4 when there is no slip on the driving wheels of the vehicle. When no slip occurs on the drive wheels of the vehicle, the first drive force command values Fx3 and Fx4 are selected as the control drive forces F3 and F4. On the other hand, when slip occurs on the driving wheels of the vehicle, the corrected second driving force command values Fs3 and Fs4 are always calculated to be smaller than the first driving force command values Fx3 and Fx4. This is because the corrected second driving force command values Fs3 and Fs4 are selected as the control driving forces F3 and F4 when slip occurs in the driving wheels. Further, when the driver recognizes the occurrence of slip and returns the accelerator pedal, the first driving force command values Fx3 and Fx4 are also reduced, so that the first driving force command values Fx3 and Fx4 are selected and promptly selected. It is possible to follow the operation of the driver.

  The corrected second driving force command values Fs3 and Fs4 may be set to the control driving forces F3 and F4 only when the slip state of the driving wheel is determined and the slip state is determined. In this case, when the slip amounts λ3 and λ4 exceed the target slip amount λ ′, for example, it can be determined that the drive wheels 3 and 4 are in the slip state. Further, the corrected second driving force command value may be calculated only when it is determined to be in the slip state.

  In step S11 (driving force control means), the outputs of the motors 5 and 6 are controlled based on torque command values obtained by multiplying the control driving forces F3 and F4 by the radius R of the wheels, respectively.

  The operation of this embodiment will be described with reference to FIGS. 6 and 7 summarizing the above control. FIG. 6 is a diagram illustrating vehicle slip control based on the slip amount control, and FIG. 7 is a diagram illustrating vehicle slip control according to the present embodiment. In each case, (a) is a relationship diagram between the slip amount and the road surface reaction force, and (b) is a timing chart showing changes in the driving force of the driving wheels.

  First, a conventional example will be described with reference to FIG. When the drive wheels 3 and 4 are in a slip state at time t1, the slip amounts λ3 and λ4 and the target slip amount λ ′ are converged so that the slip amounts λ3 and λ4 of the drive wheels 3 and 4 converge to the target slip amount λ ′. Based on the deviation, the driving force of the driving wheels 3 and 4 is controlled. As a result, the driving force decreases from the required driving force and becomes equal to the road surface reaction force at the target slip amount λ ′, so that the slip state of the driving wheels 3 and 4 is eliminated.

  However, since the road surface reaction force at the target slip amount λ ′ is smaller when the wheel load is small, for example, when the wheel load is small, the road surface reaction force at the time t1 and the road surface at the target slip amount λ ′. Deviation from reaction force increases. Therefore, the time required for the driving force of the driving wheels 3 and 4 to converge to the road surface reaction force at the target slip amount λ ′ becomes longer.

  Next, the present embodiment will be described with reference to FIG. When the driving wheels 3 and 4 are in a slip state at time t1, the second driving force calculated based on the motor angular acceleration so that the slip amounts λ3 and λ4 of the driving wheels 3 and 4 converge to the target slip amount λ ′. The sum of the command values Ff3 and Ff4 and the driving force correction values Fb3 and Fb4 calculated based on the difference between the slip amounts λ3 and λ4 and the target slip amount λ ′ is used as the driving force of the driving wheels 3 and 4.

  That is, when the slip state is reached, the driving force of the driving wheels 3 and 4 is switched from the first driving force command values Fx3 and Fx4 to the corrected second driving force command values Fs3 and Fs4, and the driving force is corrected. The second driving force command values Fs3 and Fs4 converge to the road surface reaction force at the target slip amount λ ′. As a result, the second driving force command values Ff3 and Ff4 are set smaller as the acceleration increases, so that even when the wheel loads W3 and W4 are small and the difference between the driving force and the road surface reaction force at the target slip amount λ ′ is large. The driving force quickly converges to the road surface reaction force. Further, since the second driving force command values Ff3 and Ff4 are determined to be values corresponding to the road surface reaction force, not only the slip is converged, but also an appropriate torque for advancing the vehicle after the slip has converged. Therefore, it is possible to prevent the slip from occurring again after the slip has converged.

  As described above, in the present embodiment, the corrected second driving force command values Fs3 and Fs4 are set to the road surface reaction force at the target slip amount λ ′, and the slip amount λ3 is set based on the second driving force command values Ff3 and Ff4. Since the driving force of the driving wheels 3 and 4 is controlled based on the deviation between λ4 and the target slip amount λ ′, the driving force and the target slip amount λ ′ when the driving wheels 3 and 4 are in the slip state are controlled. Even when the deviation from the road reaction force is large, the slip amounts λ3 and λ4 can be quickly converged to the target slip amount λ ′. Therefore, the slip state of the wheels 3 and 4 can be quickly eliminated, and deterioration of drivability and fuel consumption can be prevented.

  Furthermore, in the present embodiment, the second driving force command values Ff3 and Ff4 are calculated based on the torques Tm5 and Tm6 of the motors 5 and 6 and the rotational speeds ω3 and ω4 of the rear wheels. Even if there is a change in physical properties such as a change in tire, aging of tire rubber, tire replacement, etc., it is not necessary to rewrite the program or parameters of the in-vehicle computer, so that the maintainability can be improved.

(Second Embodiment)
In this embodiment, a part of the calculation method of the second driving force command value is different from that of the first embodiment. Hereinafter, a method of calculating the second driving force command values Ff3 and Ff4 in the present embodiment will be described.

  In the present embodiment, values obtained by applying a first-order lag filter to the second driving force command values Ff3 and Ff4 of the rear wheels 3 and 4 are set as second driving force command values Ff3 and Ff4. The first-order lag filter is applied based on the following equations (15) and (16) obtained by discretizing a first-order lag transfer function.

  Here, Ts is a first-order delay time constant, and is set to 1.0, for example.

  The operation of the present embodiment will be described with reference to FIGS. FIG. 8 is a timing chart showing the driving state of the vehicle when the road surface reaction force is the driving force basic value. FIG. 9 is a timing chart showing the driving state of the vehicle when the value obtained by applying the first-order lag filter to the second driving force command value is used as the driving force basic value. In either case, (a) shows the vehicle speed, (b) shows the slip amount of the wheel, and (c) shows the driving force.

  First, the case where the delay filter is not applied to the second driving force command values Ff3 and Ff4 will be described with reference to FIG. While traveling on a road surface having a low road surface friction coefficient, the driving force of the driving wheels 3 and 4 gradually increases, and at the time t1, the slip amounts λ3 and λ4 of the driving wheels 3 and 4 increase to become a slip state. As the slip amounts λ3 and λ4 increase, the road reaction force calculated based on the torques Tm5 and Tm6 of the motors 5 and 6 and the rotational speeds ω3 and ω4, that is, the second driving force command values Ff3 and Ff4 decrease. Thereafter, the increase in the slip amount is suppressed by the decrease in the second driving force command values Ff3 and Ff4, and the slip amount starts to decrease.

  Here, the driving force correction amounts Fb3 and Fb4 and the second driving force command values Ff3 and Ff4 calculated based on the difference between the target slip amount λ ′ and the slip amounts λ3 and λ4 are caused by disturbance, communication delay, and the like. When overshooting the driving force corresponding to the road surface reaction force, not only the driving force correction amounts Fb3 and Fb4 but also the second driving force command values Ff3 and Ff4 are corrected. In this case, since both perform corrections for overshoot, the second driving force command value and the target slip amount are corrected at substantially the same frequency, and the vibrations of the target driving forces Fs3 and Fs4, which are the sum of the two companies. Is encouraged. As a result, the driving force of the driving wheels 3 and 4 is hunted, so that the slip amount λ ′ of the driving wheels 3 and 4 cannot be quickly converged to the target slip amounts λ3 and λ4.

  Next, a case where values obtained by applying a first-order lag filter to the second driving force command values Ff3 and Ff4 will be described with reference to FIG. While traveling on a road surface with a low road surface friction coefficient, the driving force of the drive wheels 3 and 4 gradually increases, and at time t1, the slip amounts λ3 and λ4 of the drive wheels increase to enter a slip state. As the slip amounts λ3 and λ4 increase, the second driving force command values Ff3 and Ff4 decrease. Thereafter, the increase in the slip amounts λ3 and λ4 is suppressed by the decrease in the second driving force command values Ff3 and Ff4, and the slip amounts λ3 and λ4 start to decrease.

  Here, the driving force correction amounts Fb3 and Fb4 and the second driving force command values Ff3 and Ff4 calculated based on the difference between the target slip amount λ ′ and the slip amounts λ3 and λ4 are caused by disturbance, communication delay, and the like. Even when the driving force corresponding to the road surface reaction force is overshot, the driving force corresponding to the road surface reaction force is obtained by using a value obtained by applying a first-order lag filter to the second driving force command values Ff3 and Ff4. Therefore, with respect to the driving force equivalent to the road surface reaction force, the overshoot is not corrected at least at that time. On the other hand, since there is no delay with respect to the driving force correction amounts Fb3 and Fb4, the difference between the target slip amount λ ′ and the slip amounts λ3 and λ4 is corrected. Therefore, the correction timing of both is asynchronous, and the vibration of the driving force basic values Ff3 and Ff4 is suppressed. As a result, the driving force of the driving wheels 3 and 4 converges to the second driving force command values Ff3 and Ff4 without hunting, and the slip amount gradually approaches the target slip amount. Since vibration is also suppressed, vibration of the driving force basic value is further suppressed. Therefore, the slip amounts λ3 and λ4 of the wheels quickly converge to the target slip amount λ ′.

  As described above, in the present embodiment, the values obtained by applying the first-order lag filter to the second driving force command values Ff3 and Ff4 of the rear wheels 3 and 4 are set as the driving force basic values Ff3 and Ff4. , Fb4 becomes vibrational due to disturbance, communication delay, and the like, so that the driving force of the drive wheels 3 and 4 can be prevented from becoming vibrational. Therefore, the slip amounts λ3 and λ4 of the wheels 3 and 4 can quickly converge to the target slip amount λ ′, and the slip state of the wheels 3 and 4 can be quickly eliminated to prevent deterioration in drivability and fuel consumption.

(Third embodiment)
In the present embodiment, the first-order lag filter described in the second embodiment is cut under a predetermined condition. Other controls are the same as in the second embodiment. Hereinafter, a method of calculating the second driving force command values Ff3 and Ff4 in the present embodiment will be described with reference to FIG. FIG. 10 is a flowchart showing calculation control of the second driving force command values Ff3 and Ff4 in the present embodiment.

  In step S21, filter cut flags f3 and f4 are set. The filter cut flags f3 and f4 are set to 1 if the slip amounts λ3 and λ4 of the rear wheels 3 and 4 are larger than the filter cut threshold λth, and are set to 0 if they are smaller than the threshold λth. Here, the filter cut threshold value λth is a threshold value for determining whether or not it is necessary to temporarily cut the first-order lag filter, and in this embodiment, is the same value as the target slip amount λ ′.

  In step S22, the filter cut flags f3 and f4 at the previous processing are set to f3 (k−1) and f4 (k−1).

  In step S23, second driving force command values Ff3 and Ff4 are calculated. Here, a method for calculating the second driving force command value Ff3 for the left rear wheel 3 will be described, but the second driving force command value Ff4 is also calculated for the right rear wheel 4 in the same manner as the left rear wheel 3.

  When the value obtained by subtracting the filter cut flag f3 (k−1) at the previous processing from the filter cut flag f3 is 1, prohibiting the first-order lag filter from being applied to the second driving force command value Ff3; That is, the first-order lag filter is cut and the second driving force command value is output.

  If the value obtained by subtracting the initial value setting flag f3 (k-1) at the time of the previous processing from the initial value setting flag f3 is not 1, the value obtained by applying the first-order lag filter to the second driving force command value Ff3 is set to the second value. The driving force command value is Ff3.

  The operation of this embodiment will be described with reference to FIGS. 11 and 12 summarizing the above control. FIG. 11 is a timing chart showing the driving state of the vehicle when the primary delay filter is not cut. FIG. 12 is a timing chart showing the driving state of the vehicle when the primary delay filter is cut. In either case, (a) shows the slip amount of the wheel, and (b) shows the driving force.

  First, the case where the primary delay filter is not cut will be described with reference to FIG. At time t1, when the first driving force command values Fx3 and Fx4 that are the driver's requested driving force increase while the vehicle is traveling, the torques of the motors 5 and 6 increase, so that the second driving force command value Ff3 that is calculated is calculated. Ff4 increases. Along with this, the slip amounts λ3 and λ4 of the drive wheels 3 and 4 increase. At this time, the second driving force command values Ff3 and Ff4 are set to the second driving force command values Ff3 and Ff4, so that the second driving force command values Ff3 and Ff4 rise slowly. However, it takes time until the difference between the second driving force command values Ff3 and Ff4 and the driving force corresponding to the road surface reaction force becomes small.

  Next, a case where the first-order lag filter is cut will be described with reference to FIG. At time t1, when the driver's first driving force command values Fx3 and Fx4 increase while the vehicle is traveling, the torques of the motors 5 and 6 increase, so that the calculated second driving force command values Ff3 and Ff4 increase. Along with this, the slip amounts λ3 and λ4 of the drive wheels 3 and 4 increase. At this time, the values obtained by applying the first-order lag filter to the second driving force command values Ff3 and Ff4 are set as the second driving force command values Ff3 and Ff4, so that the second driving force command value gradually increases. Immediately thereafter, when the slip amount exceeds the filter cut threshold at time t2, the first-order lag filter is temporarily cut, so that the second driving force command values Ff3 and Ff4 increase stepwise. As a result, the second driving force command values Ff3 and Ff4 immediately follow the driving force of the road surface reaction force that has suddenly changed. Thereafter, the second driving force command values Ff3 and Ff4 are values subjected to a first-order lag filter.

  As described above, in the present embodiment, when the slip amounts λ3 and λ4 exceed the filter cut threshold λth, which is the target slip amount λ ′, for example, the first-order lag filter is temporarily cut and the second driving force command value Ff3 , Ff4 is calculated, so that the second driving force command values Ff3 and Ff4 can be quickly converged to the driving force corresponding to the road surface reaction force after the driver's required driving force increases rapidly. Therefore, the responsiveness of the driving force to changes in the driver's required driving forces Fx3 and Fx4 can be improved, and the drivability of the vehicle can be improved.

(Fourth embodiment)
In the present embodiment, the calculation method of the control driving forces F3 and F4 in step S10 in the control shown in the flowchart of FIG. 2 is different from those in the first to third embodiments. Other configurations and controls are the same. Hereinafter, a method of calculating the control driving forces F3 and F4 in the present embodiment will be described with reference to FIG. FIG. 13 is a flowchart showing calculation control of the control driving forces F3 and F4 in this embodiment.

  In step S31, slip start flags fs3 and fs4 are set. The slip start flags fs3 and fs4 are set to 1 if the slip amounts λ3 and λ4 of the rear wheels 3 and 4 are larger than the slip start threshold λths, and are set to 0 if they are less than the slip start threshold λths. The slip start threshold λths is set to the target slip amount λ ′, for example.

  In step S32, slip end flags fe3 and fe4 are set. The slip end flags fe3 and fe4 are set to 1 if the slip amounts λ3 and λ4 of the rear wheels 3 and 4 are smaller than the slip end threshold λthe, and are set to 0 if they are equal to or greater than the slip end threshold λthe. For example, the slip end threshold λthe is set to a value λthe = 0.15−0.05 = 0.1 obtained by subtracting 0.05 from the target slip amount λ ′ (for example, 0.15).

  In step S33, slip flags fth3 and fth4 are set. The slip flags fth3 and fth4 are set to 1 if the slip start flags fths3 and fths4 are 1, and are set to 0 if the slip end flags fe3 and fe4 are 1. If the slip start flags fths3 and fths4 and the slip end flags fe3 and fe4 are both 0, the slip flags fth3 and fth4 are not changed. The slip flags fth3 and fth4 are set to 0 as initial values.

  In step S34, control driving forces F3 and F4 are calculated. If the slip flags fth3 and fth4 are 0, the first driving force command values Fx3 and Fx4 calculated in step S6 of FIG. The corrected second driving force command values Fs3 and Fs4 calculated in step S9 of step 2 are set as control driving forces F3 and F4.

  As described above, in the present embodiment, in addition to determining whether or not the wheels 3 and 4 are in the slip state based on the slip amounts λ3 and λ4, it is determined that the wheels 3 and 4 are in the slip state. Since the slip start threshold value λths to be used and the slip end threshold value λthe for determining that the wheels 3 and 4 are no longer in the slip state are set to different values, the control driving force F3 and F4 are set to the first driving force command values Fx3 and Fx4, respectively. Generation of hunting when switching between the corrected second driving force command values Fs3 and Fs4 can be prevented. As a result, the driving force of the driving wheels 3 and 4 quickly converges to the desired driving force, so that the drivability and fuel efficiency of the vehicle can be improved.

  The present invention is not limited to the embodiment described above, and various modifications and changes can be made within the scope of the technical idea.

  For example, although the present embodiment has been described using a vehicle that drives only the rear wheels 3 and 4, a vehicle that drives the four wheels independently may be used. In this case, the vehicle speed V may be calculated as an average value of the four wheels, and the control of the present invention may be executed for the front wheels 1 and 2 as well.

  Moreover, although the vehicle speed V is detected using the wheel speed sensor 9, it may be detected using a GPS navigation system.

  Furthermore, the present invention is also applicable to a vehicle in which left and right wheels are directly connected and driven by one motor 1, 2 or engine, or a vehicle driven by a drive system in which the motor 1, 2 and engine are combined. In this case, the control of the present invention may be executed with the left and right wheels regarded as one wheel.

  Furthermore, the present invention can also be applied to a vehicle in which left and right wheels are connected with a differential gear. In this case, the control of the present invention may be executed by combining the brakes of the driving wheels so that the driving forces of the left and right wheels can be adjusted independently. Moreover, you may perform control of this invention so that the slip of a wheel with larger slip amount among right-and-left wheels may be eliminated.

It is a schematic block diagram which shows the slip control apparatus of the vehicle in this embodiment. It is a flowchart which shows control of the slip control apparatus of the vehicle in this embodiment. It is a map which shows the relationship between a vehicle speed, a driving force, and an accelerator pedal operation amount. It is a table which shows the relationship between a brake pedal operation amount and braking force. It is a map which shows the relationship between the target value of the driving force difference of a right-and-left driving wheel, a vehicle speed, and the steering angle of a steering. It is a figure explaining the slip control of the vehicle in a prior art example. It is a figure explaining slip control of vehicles in this embodiment. It is the timing chart which showed the driving | running state of the vehicle in case road surface reaction force is made into driving force basic value. It is the timing chart which showed the driving | running state of the vehicle in case the value which gave the 1st delay filter to the 2nd driving force command value is made into driving force basic value. It is a flowchart which shows the calculation control of the 2nd driving force command value in this embodiment. It is the timing chart which showed the driving | running state of the vehicle when not cutting a primary delay filter. It is the timing chart which showed the driving | running state of the vehicle in the case of cutting a primary delay filter. It is a flowchart which shows the calculation control of the driving force for control in this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Left front wheel 2 Right front wheel 3 Left rear wheel 4 Right rear wheel 5 Motor 6 Motor 7 Inverter 8 Inverter 9 Battery 10 Wheel speed sensor 11 Wheel speed sensor 12 Wheel speed sensor 13 Wheel speed sensor 14 Steering 15 Steering angle sensor 16 Steering angle sensor 17 Steering angle sensor 18 Steering angle sensor 19 Acceleration sensor 20 Yaw rate sensor 21 Steering angle sensor 22 Accelerator stroke sensor 23 Accelerator pedal 24 Brake stroke sensor 25 Brake pedal 30 Controller

Claims (3)

In the slip control device for vehicle drive wheels,
A drive source for driving the wheels;
Driving force control means for controlling the driving force of the driving source based on the driving force command value;
First driving force command value calculating means for calculating a first driving force command value based on a driver's request;
Second driving force command value calculating means for calculating a second driving force command value based on the driving force of the driving source and the angular acceleration of the driving wheel;
Slip amount calculating means for calculating the slip amount of the drive wheel;
Correction means for calculating a driving force correction value for converging the slip amount calculated by the slip amount calculating means to a target slip amount and correcting the second driving force command value;
Delay means for adding the driving force command value calculated by the second driving force command value calculating means as a value delayed from the correction value calculated by the correcting means;
Switching means for switching the driving force command value to the driving force control means from the first driving force command value to the second driving force command value when the driving wheel is in a slip state;
A slip control device for a vehicle drive wheel. 2. The vehicle drive wheel slip control device according to claim 1, wherein when the slip amount of the drive wheel is equal to or greater than a predetermined threshold, the delay means prohibits the delay. The switching means has a first threshold value for determining that the driving wheel is in a slip state based on the slip amount, and the first threshold value for determining that the slip state of the driving wheel has converged based on the slip amount. The slip control device for vehicle drive wheels according to claim 1, further comprising a second threshold value smaller than the second threshold value.

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