Vehicle control device and vehicle control method

Abstract

One aspect of the present invention provides a vehicle control device and a vehicle control method wherein: a first braking force generated by a front braking-driving device and a first driving force generated by a rear braking-driving device are obtained on the basis of the velocity of a vehicle and a physical quantity pertaining to the steering angle of the vehicle in primary steering, which is a state in which a steering wheel of the vehicle is being turned to the right or left direction from the neutral position; and a first control command for generating the first braking force and the first driving force is output. Thus, it is possible to improve the turning performance of the vehicle without generating acceleration and deceleration that are not intended by a driver.

Description

Technical Field

[0001] The present invention relates to a vehicle control device and a vehicle control method.

Background Art

[0002] The vehicle motion control device of Patent Document 1 includes a yaw moment control unit that controls the yaw moment generated in the vehicle by the difference in the driving forces of the left and right wheels of the vehicle according to the lateral motion of the vehicle. In a first period predicted when the lateral motion of the vehicle changes from a state where the vehicle is performing lateral motion on one side to a state where it is performing lateral motion on the other side, the yaw moment generated in the vehicle is controlled. In a second period predicted by the lateral motion prediction unit when the lateral motion of the vehicle changes from a state where the vehicle is performing lateral motion to a state where it is not performing lateral motion, the absolute value of the deceleration generated in the vehicle is made smaller than the absolute value of the deceleration generated in the vehicle in the first period.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in vehicle motion control that controls the pitching motion of a vehicle by the longitudinal acceleration of the vehicle and the difference in the driving forces of the left and right wheels of the vehicle, there is a possibility that the driver may feel discomfort due to the occurrence of acceleration and deceleration that the driver does not intend.

[0005] The present invention has been made in view of the conventional situation, and an object thereof is to provide a vehicle control device and a vehicle control method capable of improving the turning performance of a vehicle without generating acceleration and deceleration that the driver does not intend.

Means for Solving the Problems

[0006] According to one embodiment of the present invention, when the steering wheel of a vehicle is turned in either the left or right direction from the neutral position during primary steering, a first braking force to be generated by the front brake drive unit and a first driving force to be generated by the rear brake drive unit are determined based on the vehicle's speed and a physical quantity relating to the vehicle's steering angle, and a first control command to generate the first braking force and the first driving force is output. [Effects of the Invention]

[0007] According to the present invention, the turning performance of a vehicle can be improved without causing unintended acceleration or deceleration by the driver. [Brief explanation of the drawing]

[0008] [Figure 1] This is an overall configuration diagram showing the vehicle control system 1. [Figure 2] This is a block diagram that schematically shows the braking and driving control systems. [Figure 3] This is a block diagram showing a first embodiment of the turning control. [Figure 4] This is a diagram illustrating the torque map. [Figure 5] This figure shows the correlation between vehicle speed V and braking / driving torque T. [Figure 6] This figure shows the correlation between the absolute value of the steering angular velocity Δθ ​​|Δθ| and the braking / driving torque T. [Figure 7] This diagram illustrates the correlation between the absolute value of the rudder angle θ and the second gain G2. [Figure 8] This diagram illustrates the correlation between the brake operation amount and the third gain G3. [Figure 9] This figure illustrates the changes in the vehicle state when performing the turning control of the first embodiment. [Figure 10] This is a block diagram showing a second embodiment of the turning control. [Figure 11] This figure illustrates the changes in the vehicle state when performing the turning control according to the second embodiment. [Figure 12] This is a block diagram showing a third embodiment of the turning control. [Figure 13] This is a block diagram showing the primary steering / secondary steering determination unit and the rate limit determination unit in the third embodiment. [Figure 14] This figure illustrates the changes in the vehicle state when the turning control of the third embodiment is implemented. [Figure 15] This is a flowchart showing the turning control process for making decisions regarding primary and secondary steering. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the vehicle control device and vehicle control method according to the present invention will be described with reference to the drawings. Figure 1 is an overall configuration diagram showing the vehicle control system 1 installed in the vehicle 10. Figure 2 is a block diagram schematically showing the braking and driving control systems of the vehicle control system 1. The vehicle 10 is equipped with a pair of left and right front wheels 11, 12 and a pair of left and right rear wheels 13, 14.

[0010] Furthermore, the vehicle 10 includes a front motor 71 that provides driving force to the front wheels 11 and 12, and a rear motor 73 that provides driving force to the rear wheels 13 and 14, as drive force actuators that provide driving force to the vehicle 10. The front motor inverter 72 controls the drive of the front motor 71, and the rear motor inverter 74 controls the drive of the rear motor 73.

[0011] The front motor inverter 72 and the rear motor inverter 74 each have an inverter circuit and an ECU (Electronic Control Unit) that outputs signals to control the inverter circuit. The ECUs of the front motor inverter 72 and the rear motor inverter 74 acquire information on the operation amount of the accelerator pedal 63 from the accelerator pedal sensor 64, and output a control signal corresponding to the target driving force based on the operation amount of the accelerator pedal 63 to the inverter circuit, thereby generating a driving force corresponding to the operation amount of the accelerator pedal 63 with the front motor 71 and the rear motor 73.

[0012] Further, the vehicle 10 includes a steering device that changes the steering angle of the front wheels 11, 12, which are the steered wheels, in accordance with the steering operation of the steering wheel 51. The steering wheel 51 includes a steering angle sensor 52 that detects the rotation angle of the steering wheel 51 as the steering angle.

[0013] Further, the vehicle 10 includes a braking device. The braking device has a brake control unit 32, a brake pedal sensor 62 that detects the operation amount of the brake pedal 61, and brake actuators 15, 16, 17, 18 provided on each of the wheels 11, 12, 13, 14.

[0014] The brake control unit 32 controls the frictional braking force applied to each of the wheels 11, 12, 13, 14 by the brake actuators 15, 16, 17, 18 based on the output of the brake pedal sensor 62. Note that the front motor 71 and the rear motor 73 are used as power sources and selectively perform a regenerative operation. The front motor 71 constitutes a front drive device that applies a driving force to the front wheels 11, 12, and the rear motor 73 constitutes a rear drive device that applies a driving force to the rear wheels 13, 14.

[0015] The vehicle control unit 31 acquires a signal related to the steering angle from the steering angle sensor 52. Then, the vehicle control unit 31 outputs a control command related to drive to the brake control unit 32, the ECU of the front motor inverter 72, and the ECU of the rear motor inverter 74. The microcomputers in the front motor inverter 72's ECU, the rear motor inverter 74's ECU, the brake control unit 32, and the vehicle control unit 31 are equipped with an MPU (Microprocessor Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc., and various functions are realized by running the program stored in the ROM, which acts as a memory unit, using the MPU.

[0016] In the vehicle control system 1, the microcomputer, which is a control unit of the vehicle control device 31, performs turning control to improve the turning performance of the vehicle 10 without causing unintended acceleration or deceleration when the vehicle 10 turns. In turning control, when the steering wheel 51 is turned in either the left or right direction from the neutral position (primary steering), the vehicle control unit 31 determines a first braking force to be generated by the front brake / drive system and a first driving force to be generated by the rear brake / drive system based on the speed of the vehicle 10 and a physical quantity related to the steering angle of the vehicle 10, and outputs a first control command to generate the first braking force and the first driving force. This turning control increases the lateral acceleration of the vehicle 10, which in turn increases the amount of lateral movement, thereby improving the turning performance of the vehicle 10.

[0017] "First Embodiment" The following describes a first embodiment of the turning control. Figure 3 is a block diagram showing the functional components of the vehicle control unit 31 for turning control in the first embodiment.

[0018] The differential unit 101 obtains a signal of the rudder angle θ [deg] from the rudder angle sensor 52, and calculates the rudder angular velocity Δθ ​​[deg / s] by differentiating the rudder angle θ with respect to time. Note that the rudder angle θ is zero when the steering is in the neutral position (in other words, the straight-ahead position), and the left and right directions from the neutral position are represented by positive and negative signs, respectively. The absolute value calculation unit 102 obtains the signal of the rudder angular velocity Δθ ​​from the differentiation unit 101 and calculates the absolute value of the rudder angular velocity Δθ, |Δθ|.

[0019] The torque calculation unit 103 acquires a signal of the absolute value of the steering angular velocity Δθ ​​|Δθ| and a signal of the vehicle speed V [km / h], and calculates the braking and driving torque T [Nm] (T≧0) applied to the front and rear wheels based on the absolute value of the steering angular velocity Δθ ​​|Δθ| and the vehicle speed V. Here, the torque calculation unit 103 refers to a torque map in which a braking / driving torque T is set for each combination of the absolute value of the steering angular velocity Δθ ​​|Δθ| and the vehicle speed V, and searches for the braking / driving torque T that corresponds to the absolute value of the steering angular velocity Δθ ​​|Δθ| and the vehicle speed V at that time.

[0020] The torque map is stored in non-volatile memory, such as ROM, of the microcomputer in the vehicle control unit 31. However, the configuration is not limited to determining the braking and driving torque T using a torque map; the torque calculation unit 103 can determine the braking and driving torque T by a calculation process that uses the absolute value of the steering angular velocity Δθ ​​|Δθ| and the vehicle speed V as variables.

[0021] Figure 4 shows an overview of the torque map. In the torque map, in the region where the vehicle speed V is less than or equal to the first threshold THV1 (THV1>0), and in the region where the absolute value of the steering angular velocity Δθ ​​|Δθ| is less than or equal to the first threshold THθ1 (THθ1>0), the braking and driving torque T is set to zero. The first velocity threshold, THV1, is set to a speed of approximately 40 km / h, for example, and the first angular velocity threshold, THθ1, is set to approximately 50 deg / s.

[0022] The region where the braking / driving torque T is set to zero is a region where the braking / driving torque command for the turning control ultimately becomes zero, meaning that turning control does not intervene; in other words, it is a region where turning control is effectively canceled. On the other hand, in the torque map, in the region where the vehicle speed V exceeds the first threshold THV1 and the absolute value of the steering angular velocity Δθ ​​|Δθ| exceeds the first threshold THθ1, the braking and driving torque T is set to a value higher than zero.

[0023] Figure 5 shows the trend of the correlation between vehicle speed V and braking / driving torque T in the torque map shown in Figure 4. As mentioned above, when the vehicle speed V is less than or equal to the first threshold THV1, the braking and driving torque T is set to zero, and cornering control does not intervene. Furthermore, the braking and driving torque T reaches a maximum value in the region where the vehicle speed V exceeds the first threshold THV1. In other words, if we define the second speed threshold, THV2, as the vehicle speed V at which the braking / driving torque T reaches its maximum value, then the braking / driving torque T increases in proportion to the increase in vehicle speed V when the vehicle speed V is between the first threshold THV1 and the second threshold THV2, and decreases in proportion to the increase in vehicle speed V when the vehicle speed V exceeds the second threshold THV2.

[0024] Figure 6 shows the trend of the correlation between the absolute value of the steering angular velocity Δθ| and the braking / driving torque T in the torque map shown in Figure 4. As mentioned above, when the absolute value of the steering angular velocity Δθ ​​|Δθ| is less than or equal to the first threshold THθ1, the braking and driving torque T is set to zero, and turning control does not intervene. Furthermore, the braking and driving torque T reaches a maximum value in the region where the absolute value of the steering angular velocity Δθ ​​|Δθ| exceeds the first threshold THθ1. In other words, if the absolute value |Δθ| at which the braking / driving torque T reaches its maximum value is defined as the second threshold THθ2 (second angular velocity threshold), then the braking / driving torque T increases in proportion to the increase in the absolute value |Δθ| of the steering angular velocity Δθ ​​when the absolute value |Δθ| of the steering angular velocity Δθ ​​is between the first threshold THθ1 and the second threshold THθ2, and decreases in proportion to the increase in the absolute value |Δθ| of the steering angular velocity Δθ ​​when the absolute value |Δθ| of the steering angular velocity Δθ ​​exceeds the second threshold THθ2.

[0025] As described above, when the vehicle speed V is less than or equal to the first threshold THV1, and / or the absolute value of the steering angular velocity Δθ|Δθ| is less than or equal to the first threshold THθ1, the effectiveness of cornering control is low, so the torque map is set so that cornering control does not intervene. On the other hand, in the region where the vehicle speed V exceeds the first threshold THV1 and the absolute value of the steering angular velocity Δθ ​​|Δθ| exceeds the first threshold THθ1, the torque map is set so that cornering control intervenes. However, if the absolute value of the vehicle speed V or steering angular velocity Δθ| exceeds a certain value of the second threshold THθ2, the vehicle 10 may become unstable due to the turning control. Therefore, the torque map is set to suppress the braking and driving force applied by the turning control.

[0026] The torque calculation unit 103 outputs a signal of the braking / driving torque T, which is determined based on the absolute value |Δθ| of the steering angular velocity Δθ ​​and the vehicle speed V, to the first multiplication unit 104. The first multiplication unit 104 outputs the result of multiplying the braking torque T by the first gain G1 as a signal of the required braking torque Ttg. Here, the first gain G1 is set based on the second gain G2, which is based on the steering angle θ, and the third gain G3, which is based on the amount of brake operation (G1 = G2 × G3).

[0027] The second gain setting unit 105 acquires the rudder angle θ signal and outputs a second gain G2 signal based on the rudder angle θ. Figure 7 illustrates the correlation between the absolute value of the rudder angle θ and the second gain G2 (1.0 ≥ G2 ≥ 0). The second gain setting unit 105 sets the second gain G2 to zero when the rudder angle θ is zero and in the neutral position (neutral angle), and sets the second gain G2 to a larger value as the absolute value of the rudder angle θ increases within the range of 1.0 ≥ G2 ≥ 0. In other words, when the steering angle θ is near the neutral position, the second gain G2 based on the steering angle θ is set to zero or near zero, so the required drive torque Ttg output by the first multiplier unit 104 is set to zero or near zero, and the required drive torque Ttg increases as the steering angle θ moves away from the neutral position.

[0028] The third gain setting unit 106 acquires a signal of the brake operation amount (in other words, the amount of operation of the brake pedal 61) from the brake pedal sensor 62 and outputs a signal of the third gain G3 based on the brake operation amount. Figure 8 illustrates the correlation between the brake operation amount and the third gain G3 (1.0 ≥ G3 ≥ 0). The third gain setting unit 106 sets the third gain G3 to 1.0 when the brake operation amount is zero and no brake operation is performed, and approaches zero as the brake operation amount increases (in other words, as the required frictional braking force increases). In other words, the greater the amount of braking operation performed by the driver, the smaller the required braking torque Ttg output by the first multiplier unit 104 becomes, thereby preventing the application of braking force by the turning control from hindering the realization of the rapid deceleration request.

[0029] The second multiplication unit 107 acquires the signal for the second gain G2 from the second gain setting unit 105 and the signal for the third gain G3 from the third gain setting unit 106. The second multiplier unit 107 then outputs the result of multiplying the second gain G2 by the third gain G3 as the first gain G1 (G1 = G2 × G3) to the first multiplier unit 104. The first multiplication unit 104 outputs a signal of the required braking / driving torque Ttg (Ttg = T × G1) by multiplying the first gain G1, which is based on the second gain G2 and the third gain G3, by the braking / driving torque T obtained by the torque calculation unit 103.

[0030] The limiter control unit 108 acquires the signal of the requested braking torque Ttg output by the first multiplication unit 104, limits the requested braking torque Ttg to within the torque range that the braking force system of the vehicle control system 1 can output, and outputs it. In other words, if the requested driving torque Ttg output by the first multiplication unit 104 exceeds the upper limit value Ttgmax, the limiter control unit 108 outputs the upper limit value Ttgmax as the requested driving torque Ttg. Furthermore, if the requested drive torque Ttg output by the first multiplier unit 104 is less than or equal to the upper limit value Ttgmax, the limiter control unit 108 outputs the requested drive torque Ttg output by the first multiplier unit 104 as the requested drive torque Ttg.

[0031] The limiter control unit 108 outputs a signal of the required drive torque Ttg, limited to the upper limit value Ttgmax or less, to the third multiplier unit 109 as the required drive torque TtgF for the front wheels 11 and 12, and to the front / rear distribution ratio control unit 110 as the required drive torque TtgR for the rear wheels 13 and 14. The third multiplier unit 109 multiplies the signal of the required drive torque Ttg obtained from the limiter control unit 108 by a fixed value of -1, thereby inverting the sign of the required drive torque Ttg from positive to negative.

[0032] In this application, a positive required driving torque Ttg indicates a required driving torque, and a negative required driving torque Ttg indicates a required braking torque. Therefore, the process by which the third multiplier unit 109 multiplies the signal of the requested braking torque Ttg by -1 is equivalent to setting the requested braking torque TtgF of the front wheels 11 and 12 to a braking request. On the other hand, the required drive torque TtgR for the rear wheels 13 and 14 is supplied to the front-to-rear distribution ratio control unit 110 with the same sign as the output of the limiter control unit 108, resulting in a positive required drive torque Ttg, that is, a drive torque requirement.

[0033] The front-to-rear torque distribution control unit 110 acquires signals for a negative requested braking / driving torque TtgF, a positive requested braking / driving torque TtgR, and the driver's requested torque, and performs the front-to-rear torque distribution of the braking / driving torque, as described later, according to the driver's requested torque. The front-to-rear distribution ratio control unit 110 then outputs a braking torque command to the front motor 71 based on the requested braking torque TtgF after distribution control, causing the front motor 71 to generate regenerative torque (in other words, braking torque). Furthermore, the front-to-rear distribution ratio control unit 110 outputs a drive torque command to the rear motor 73 based on the requested drive torque TtgR after distribution control, causing the rear motor 73 to generate motor torque (in other words, drive torque).

[0034] Here, the front-to-rear distribution ratio control unit 110 basically sets the front-to-rear distribution ratio to 50:50, so that the magnitude of the braking and driving force applied to the front wheels 11 and 12 is the same as the magnitude of the braking and driving force applied to the rear wheels 13 and 14, in order to prevent acceleration and deceleration of the vehicle 10, and so that the braking and driving force applied by the cornering control cancels out between the front and rear wheels. In other words, the limiter control unit 108 outputs a braking torque equivalent to the required braking torque Ttg to the front wheels 11 and 12, and the limiter control unit 108 outputs a driving torque equivalent to the required braking torque Ttg to the rear wheels 13 and 14. This prevents unintended acceleration or deceleration from occurring due to the implementation of turning control.

[0035] Furthermore, the front-to-rear distribution ratio control unit 110 sets the front-to-rear distribution ratio from the basic value of 50:50 to a predetermined distribution ratio other than 50:50, depending on the acceleration and deceleration state of the vehicle 10. The front-to-rear distribution ratio control unit 110 sets the distribution ratio between the amount of braking force applied to the front wheels 11 and 12 and the amount of driving force applied to the rear wheels 13 and 14 to, for example, 40:60, when the vehicle 10 is accelerating. In other words, the front-to-rear distribution ratio control unit 110 reduces the amount of braking force applied to the front wheels 11 and 12 compared to when the front-to-rear distribution ratio is the basic value of 50:50, while relatively increasing the amount of driving force applied to the rear wheels 13 and 14 compared to when the front-to-rear distribution ratio is the basic value of 50:50.

[0036] The front-to-rear distribution ratio control unit 110, for example, when the vehicle 10 is accelerating and the drive torque generated by the rear motor 73 due to the intervention of cornering control is likely to exceed a limit, sets a distribution ratio that relatively reduces the braking force applied to the front wheels 11 and 12 during cornering control. As a result, the driving force applied to the rear wheels 13 and 14 is reduced to offset the braking force applied to the front wheels 11 and 12, which in turn allows the rear motor 73 to generate a larger driving force for acceleration, making it possible to satisfy the driver's acceleration demands with motor torque within the limits.

[0037] Furthermore, when the vehicle 10 decelerates, the front-to-rear distribution ratio control unit 110 sets the distribution ratio between the amount of braking force applied to the front wheels 11 and 12 and the amount of driving force applied to the rear wheels 13 and 14 to, for example, 60:40. In other words, the front-to-rear distribution ratio control unit 110 increases the amount of braking force applied to the front wheels 11 and 12 compared to when the front-to-rear distribution ratio is the basic value of 50:50, while relatively decreasing the amount of driving force applied to the rear wheels 13 and 14 compared to when the front-to-rear distribution ratio is the basic value of 50:50.

[0038] The front-to-rear distribution ratio control unit 110, for example, when the vehicle 10 is decelerating and the regenerative torque generated by the front motor 71 due to the intervention of cornering control is likely to exceed a limit, sets a distribution ratio that relatively reduces the driving force applied to the rear wheels 13 and 14 during cornering control. As a result, the braking force applied to the front wheels 11 and 12 is reduced to offset the driving force applied to the rear wheels 13 and 14. This allows the braking force (in other words, regenerative torque) that can be generated by the front motor 71 for deceleration to be increased, making it possible to satisfy the driver's deceleration request with regenerative torque within the limit.

[0039] Figure 9 illustrates the changes in the vehicle state when cornering control is performed, applying braking force to the front wheels 11 and 12 and driving force to the rear wheels 13 and 14. Figure 9 shows the changes in steering angle θ [deg], lateral acceleration [G], lateral displacement [m], braking / driving torque [Nm] of the front wheels 11 and 12, and braking / driving torque [Nm] of the rear wheels 13 and 14 when vehicle 10 changes lanes from the left lane to the right lane while traveling on a road with two lanes in each direction.

[0040] Let's assume that the driver begins turning the steering wheel 51 from the neutral position to the right at time t1 in order to change lanes (in other words, to turn). At this time, the vehicle control unit 31 determines the steering operation (i.e., primary steering) based on the change in steering angle θ, increases the required braking torque Ttg, and outputs control commands to the front braking and driving units to apply braking torque to the front wheels 11 and 12 and driving torque to the rear wheels 13 and 14. The braking and driving control increases the lateral acceleration of the vehicle 10, which in turn increases the lateral movement of the vehicle 10, thereby improving its turning performance. Furthermore, the braking torque applied to the front wheels 11 and 12 and the driving torque applied to the rear wheels 13 and 14 cancel each other out, preventing unintended acceleration and deceleration by the driver.

[0041] "Second Embodiment" The following describes a second embodiment of the turning control. In the second embodiment, the vehicle control unit 31 determines whether the steering wheel 51 is turned in one direction to the left or right from the neutral position (primary steering) or whether the steering wheel 51 is turned in the other direction after the primary steering. The vehicle control unit 31 then applies braking force to the front wheels 11 and 12 and driving force to the rear wheels 13 and 14 during primary steering, and switches to a state where it applies driving force to the front wheels 11 and 12 and braking force to the rear wheels 13 and 14 during secondary steering.

[0042] In other words, when primary steering is performed, the vehicle control unit 31 determines a first braking force to be generated by the front brake drive unit and a first driving force to be generated by the rear brake drive unit based on the speed of the vehicle 10 and a physical quantity related to the steering angle θ, and outputs a first control command to generate the first braking force and the first driving force. Furthermore, when performing secondary steering after primary steering, the vehicle control unit 31 determines a second driving force to be generated by the front brake drive unit and a second braking force to be generated by the rear brake drive unit based on the speed of the vehicle 10 and a physical quantity related to the steering angle θ, and outputs a second control command to generate the second driving force and the second braking force.

[0043] Figure 10 is a block diagram showing the functional components of the vehicle control unit 31 for turning control in the second embodiment. In Figure 10, the same reference numerals are used for the same blocks as in Figure 3, and detailed explanations are omitted. The vehicle control unit 31 of the second embodiment includes, in addition to the functional unit shown in Figure 3, an absolute value calculation unit 111, a differentiation unit 112, and a fourth multiplication unit 113.

[0044] The absolute value calculation unit 111 calculates the absolute value |θ| of the rudder angle θ. The differential unit 112 calculates the rudder angular velocity Δ|θ| by differentiating the absolute value of the rudder angle θ|θ| with respect to time, and outputs a signal indicating the sign of the rudder angular velocity Δ|θ|. That is, it outputs a +1 signal when the absolute value of the rudder angle θ|θ| increases and the rudder angular velocity Δ|θ| becomes positive, and a -1 signal when the absolute value of the rudder angle θ|θ| decreases and the rudder angular velocity Δ|θ| becomes negative.

[0045] In other words, the differential unit 112 outputs a +1 signal when the steering wheel 51 is turned in either the left or right direction from the neutral position (primary steering), and outputs a -1 signal when the steering wheel 51 is turned in the other direction (secondary steering) after the primary steering. Therefore, the output signal of the differential unit 112 is a signal indicating the judgment result of primary steering and secondary steering.

[0046] As described above, the third multiplier unit 109 multiplies the signal of the required drive torque Ttg obtained from the limiter control unit 108 by a fixed value of -1, and then multiplies it by the output signal (-1 or +1) of the derivative unit 112 to output the required drive torque TtgF for the front wheels 11 and 12. Meanwhile, the fourth multiplier unit 113 multiplies the signal of the required drive torque Ttg obtained from the limiter control unit 108 by the output signal (-1 or +1) of the differential unit 112 and outputs it as the required drive torque TtgR for the rear wheels 13 and 14.

[0047] Here, when the output signal of the differential unit 112 is +1 during primary steering, the third multiplier unit 109 outputs a negative value indicating a braking request as the required braking torque TtgF for the front wheels 11 and 12, and the fourth multiplier unit 113 outputs a positive value indicating a drive request as the required braking torque TtgR for the rear wheels 13 and 14. On the other hand, when the output signal of the differential unit 112 is -1 during secondary steering, the third multiplier unit 109 outputs a positive value indicating a drive request as the required braking drive torque TtgF for the front wheels 11 and 12, and the fourth multiplier unit 113 outputs a negative value indicating a braking request as the required braking drive torque TtgR for the rear wheels 13 and 14.

[0048] In other words, during primary steering, the positive and negative values ​​of the required braking and driving torques TtgF and TtgR are set so that braking force is applied to the front wheels 11 and 12 and driving force is applied to the rear wheels 13 and 14. During secondary steering after primary steering, the positive and negative values ​​of the required braking and driving torques TtgF and TtgR are set so that driving force is applied to the front wheels 11 and 12 and braking force is applied to the rear wheels 13 and 14. Therefore, in primary steering, braking force is applied to the front wheels 11 and 12 and driving force to the rear wheels 13 and 14. When switching from primary to secondary steering, the braking and driving forces of the front and rear wheels are reversed, with driving force applied to the front wheels 11 and 12 and braking force to the rear wheels 13 and 14. According to this second embodiment, in primary steering, the lateral acceleration (in other words, the amount of lateral movement) increases, improving the turning performance of the vehicle 10, while in secondary steering, the convergence of the lateral acceleration is accelerated, improving the stability performance of the vehicle 10.

[0049] Figure 11 illustrates the changes in vehicle state in the second embodiment, where primary steering applies braking force to the front wheels 11 and 12 and driving force to the rear wheels 13 and 14, and secondary steering applies driving force to the front wheels 11 and 12 and braking force to the rear wheels 13 and 14. Here, the driver begins turning the steering wheel 51 from the neutral position to the right at time t1 in order to change lanes (in other words, to turn), and begins turning back to the neutral position at time t2.

[0050] During primary steering, when the absolute value of the steering angle θ|| increases from time t1 to time t2, braking force is applied to the front wheels 11 and 12 and driving force to the rear wheels 13 and 14, increasing the lateral acceleration (lateral displacement) of the vehicle 10 and improving the turning performance of the vehicle 10. Furthermore, during secondary steering from time t2 until time t3 when the steering wheel 51 returns to the neutral position (in other words, when the lane change is completed or when exiting a turn), driving force is applied to the front wheels 11 and 12 and braking force to the rear wheels 13 and 14, which speeds up the convergence of the vehicle 10's lateral acceleration and improves the vehicle 10's stability.

[0051] "Third Embodiment" The third embodiment of the turning control will be described below. In the third embodiment, even after returning to the neutral position by turning back, the vehicle 10's stability performance is further improved by continuing to apply driving force to the front wheels 11 and 12 and braking force to the rear wheels 13 and 14, that is, by continuing to make decisions regarding secondary steering.

[0052] Figure 12 is a block diagram showing the functional components of the vehicle control unit 31 for turning control in the third embodiment. In Figure 12, the same reference numerals are used for the same blocks as in Figures 3 and 10, and detailed explanations are omitted.

[0053] The vehicle control unit 31 of the third embodiment has a primary steering / secondary steering determination unit 120 instead of the absolute value calculation unit 111 and differential unit 112 shown in Figure 10. Furthermore, the vehicle control unit 31 of the third embodiment includes a front-to-rear distribution ratio control unit 110A which has the same function as the front-to-rear distribution ratio control unit 110 of the first embodiment, and a rate limit determination unit 140. The third multiplier unit 109 and the fourth multiplier unit 113 are configured to switch between drive requests and braking requests by switching the positive and negative values ​​of the requested braking torques TtgF and TtgR based on the primary steering and secondary steering determination signals output by the primary steering and secondary steering determination unit 120.

[0054] Here, the primary steering / secondary steering determination unit 120, similar to the second embodiment, is based on determining primary and secondary steering based on the positive or negative value of the differential Δ|θ|. However, the primary / secondary steering determination unit 120 is configured to continue determining secondary steering in the reversed state even if the differential value Δ|θ| reverses to positive after the steering angle θ returns to near the neutral position due to the reversed steering.

[0055] Figure 13 is a block diagram showing the details of the primary steering / secondary steering determination unit 120 and the rate limit determination unit 140. The absolute value calculation unit 121 calculates the absolute value |θ| of the rudder angle θ. The first switch unit 122 compares the absolute value of the rudder angle θ| with the rudder angle threshold θth (θth>0), which is a value near the neutral position. The first switch unit 122 outputs 1 when the absolute value of the steering angle θ|θ| is less than or equal to the steering angle threshold θth, that is, when the steering angle θ is within a predetermined range near the neutral position, including the neutral position. It outputs 0 when the absolute value of the steering angle θ|θ| exceeds the steering angle threshold θth, or when the steering angle θ is not near the neutral position.

[0056] The delay unit 123 retains the previous value of the output of the first switch unit 122. The first comparison unit 124 compares the output of the delay unit 123 (i.e., the previous value of the output of the first switch unit 122) with 0, and outputs 1 when the output of the delay unit 123 is 0. Furthermore, the second comparison unit 125 compares the output of the first switch unit 122 (i.e., the current value) with 1, and outputs 1 when the output of the first switch unit 122 is 1.

[0057] The logical AND operation unit 126 performs a logical AND operation between the output of the first comparison operation unit 124 and the output of the second comparison operation unit 125. Here, when the steering angle θ returns from a state away from the neutral position to near the neutral position defined by the steering angle threshold θth, the output of the first switch unit 122 switches from 0 to 1. At this time, the output of both the first comparison unit 124 and the second comparison unit 125 become 1, and the logical AND unit 126 outputs 1.

[0058] The second switch unit 127 outputs 1 when the output of the logical AND operation unit 126 is 1 or greater (i.e., the output of the logical AND operation unit 126 is 1), and outputs the output of the third switch unit 128, which will be explained later, when the output of the logical AND operation unit 126 is less than 1 (i.e., the output of the logical AND operation unit 126 is 0). The third switch unit 128 outputs 0 when the timer x output by the adder unit 130 (described later) is equal to or greater than the second threshold x2, and outputs the previous value of the output of the second switch unit 127 held by the delay unit 129 if the timer x is less than the second threshold x2. Here, the initial value of the delay unit 129 is 0.

[0059] Therefore, while the output of the logical AND operation unit 126 is 0, the output of the third switch unit 128 is also 0, and the output of the second switch unit 127 is kept at 0. Then, when the output of the logical AND operation unit 126 switches to 1, the output of the second switch unit 127 switches to 1, and the next time the output of the logical AND operation unit 126 returns to 0, the output of the delay unit 129 retains the previous value of 1, so the output of the second switch unit 127 continues to retain 1.

[0060] In other words, when the steering angle θ moves away from the neutral position and returns to the vicinity of the neutral position defined by the steering angle threshold θth, the second switch unit 127 switches from a state that outputs 0 to a state that outputs 1. The output of the second switch unit 127 is then supplied to the adder unit 130 as the sum. The adder 130 adds the output of the second switch 127 to the output of the fourth switch 131 and outputs it as timer x.

[0061] The fourth switch unit 131 resets its output to 0 when the output of the third switch unit 128 is 0, but while the output of the third switch unit 128 is 1, it outputs the previous value of the adder unit 130 held by the delay unit 132 (in other words, the previous value of timer x). In other words, when the steering angle θ returns from a state away from the neutral position to near the neutral position defined by the steering angle threshold θth, and the output of the second switch unit 127 becomes 1, the timer x, which is the output of the adder unit 130, increases by 1 each time. Then, when timer x exceeds the second threshold x2, the output of the third switch unit 128 becomes 0, which in turn causes the output of the fourth switch unit 131 to also become 0, and timer x is reset to 0.

[0062] The differentiation unit 133 obtains the absolute value |θ| of the rudder angle θ calculated by the absolute value calculation unit 121, and determines the rudder angular velocity Δ|θ| by differentiating the absolute value |θ| with respect to time. The positive / negative determination unit 134 determines whether to perform primary steering, which applies braking force to the front wheels 11 and 12 and driving force to the rear wheels 13 and 14, and secondary steering, which applies driving force to the front wheels 11 and 12 and braking force to the rear wheels 13 and 14, based on whether the steering angular velocity Δ|θ| is positive or negative.

[0063] In other words, the positive / negative determination unit 134 determines that if the steering angle |θ| is increasing, that is, if the steering angle θ is changing in a direction away from the neutral position and the steering angular velocity Δ|θ| is positive, it is in a state of primary steering where braking force is applied to the front wheels 11 and 12 and driving force to the rear wheels 13 and 14, and outputs a signal of +1. On the other hand, the positive / negative determination unit 134 determines that if the steering angle |θ| is decreasing or changing, or if the steering angle θ is changing in a direction approaching the neutral position and the steering angular velocity Δ|θ| is negative, it is in a state of secondary steering where driving force is applied to the front wheels 11 and 12 and braking force to the rear wheels 13 and 14, and outputs a signal of -1.

[0064] The fifth switch unit 135 is a functional unit that switches the output (i.e., the determination signals for primary steering and secondary steering) by comparing timer x with threshold values x1 and x2 (x2 > x1 ≥ 0). When the timer x is less than or equal to the first threshold value x1 (x ≤ x1) or when the timer x is greater than or equal to the second threshold value x2 (x ≥ x2), the fifth switch unit 135 outputs the output of the positive / negative determination unit 134 (i.e., the determination signals for primary steering and secondary steering) as it is. On the other hand, while the timer x satisfies x1 < x < x2, the fifth switch unit 135 uses the previous value of the output of the fifth switch unit 135 held by the delay unit 136 as the current output value.

[0065] For example, when the steering wheel 51 is turned from the neutral position to either the left or right, such as when a lane change is started, the steering angular velocity Δ|θ| becomes positive, and it enters a state of primary steering where braking force is applied to the front wheels 11, 12 and driving force is applied to the rear wheels 13, 14. After reaching a certain steering angle θ, when a return operation is performed to turn the steering wheel 51 back towards the neutral position, the steering angular velocity Δ|θ| becomes negative, and it switches to a state of secondary steering where driving force is applied to the front wheels 11, 12 and braking force is applied to the rear wheels 13, 14.

[0066] Here, when the steering wheel 51 is turned back near the neutral position and further turned in the reverse direction from the neutral position, the steering angular velocity Δ|θ| switches to positive. Therefore, the positive / negative determination unit 134 determines that it is in a state of primary steering where braking force is applied to the front wheels 11, 12 and driving force is applied to the rear wheels 13, 14.

[0067] On the other hand, the timer x starts counting up when the steering wheel 51 returns near the neutral position (specifically, when it reaches a predetermined steering angle immediately before the neutral position). At the start of such counting up, since the steering angular velocity Δ|θ| is negative, the positive / negative determination unit 134 is in a state of determining secondary steering.

[0068] Therefore, while the timer x satisfies x1 < x < x2, that is, during a predetermined time after the steering wheel 51 is turned back to near the neutral position, the fifth switch unit 135 continuously outputs the secondary steering determination at the start of the count-up of the timer x. As a result, when the steering wheel 51 is turned back to near the neutral position and further when the steering wheel 51 is turned in the reverse direction from the neutral position, even if the steering angular velocity Δ|θ| reverses from minus to plus by passing through the neutral position (in other words, even if the determination by the positive / negative determination unit 134 reverses from secondary steering to primary steering), the output of the fifth switch unit 135 is held at a signal of -1 indicating secondary steering, and the application of driving force to the front wheels 11, 12 is continued.

[0069] If there is no function to maintain the secondary steering determination using the timer x, when the steering angular velocity Δ|θ| reverses from minus to plus, the output of the positive / negative determination unit 134 switches from the secondary steering determination to the primary steering determination, and the control to improve stability by applying driving force to the front wheels 11, 12 switches to the control to improve turning performance by applying braking force to the front wheels 11, 12. However, when the steering wheel 51 is turned back to near the neutral position and further when it is turned in the reverse direction from the neutral position, it is a state where the turning for lane change or the like has ended, so the improvement in stability should be prioritized over the turning performance. Therefore, when the steering wheel 51 is turned back to near the neutral position and further when it is turned in the reverse direction from the neutral position, by continuing the determination of secondary steering, the stability of the vehicle 10 when the lane change (in other words, the turn) ends is improved.

[0070] By the way, the required control drive torque Ttg output by the limiter control unit 108 decreases to zero once and then rises again due to the action of the second gain G2 based on the steering angle θ when the steering angle θ passes through the neutral position. Therefore, even if the decision to perform secondary steering is continued when the steering angle θ passes the neutral position, the driving force applied to the front wheels 11 and 12 and the braking force applied to the rear wheels 13 and 14 will drop near the neutral position before rising again, and the effect of continuing the decision to perform secondary steering cannot be fully realized.

[0071] Therefore, the vehicle control unit 31 includes a rate limit determination unit 140 as a functional unit for ensuring the braking and driving force applied to the front and rear wheels when the decision on secondary steering is continued. The rate limit determination unit 140 includes a rate limit processing unit 141, a select high processing unit 142, and a sixth switch unit 143.

[0072] The rate limit processing unit 141 acquires the required braking torque TtgF signal of the front wheels 11 and 12 from the third multiplication unit 109, performs rate limit processing to limit the change in the required braking torque TtgF, and outputs the signal after rate limit processing (i.e., the braking force limit value) as the required braking torque TtgFRL. The rate limiting unit 141 will output a requested drive torque TtgFRL that decreases more slowly than the requested drive torque TtgF when the requested drive torque TtgF decreases.

[0073] The select high processing unit 142 outputs the larger of the requested drive torque TtgFRL after rate limit processing output by the rate limit processing unit 141 and the requested drive torque TtgF output by the third multiplication unit 109 as the requested drive torque TtgF. Therefore, when the requested drive torque TtgF decreases, the select high processing unit 142 selects a requested drive torque TtgFRL that is greater than the requested drive torque TtgF output by the third multiplication unit 109.

[0074] The sixth switch unit 143 outputs either the output of the select high processing unit 142 or the output of the third multiplier unit 109 as the required drive torque TtgF for the front wheels 11 and 12, based on the primary steering and secondary steering judgment signals output by the primary steering and secondary steering judgment unit 120 (fifth switch unit 135). In detail, the sixth switch unit 143 selects and outputs the output of the select high processing unit 142 when the output of the primary steering / secondary steering determination unit 120 (fifth switch unit 135) is -1, which indicates secondary steering.

[0075] On the other hand, when the output of the primary steering / secondary steering determination unit 120 (fifth switch unit 135) is +1, which indicates primary steering, the sixth switch unit 143 outputs the output of the third multiplication unit 109 as the required drive torque TtgF. Furthermore, the required drive torque TtgR for the rear wheels 13 and 14 is set as a signal with the same absolute value as the required drive torque TtgF output from the sixth switch unit 143, but with the sign inverted. Then, as described above, the requested braking and driving torques TtgF and TtgR set by the rate limit determination unit 140 are targeted by the front / rear distribution ratio control unit 110A, and finally, the braking and driving torques to be applied to the front and rear wheels are determined.

[0076] The primary / secondary steering determination unit 120 continues to make a determination on secondary steering when the steering wheel 51 is turned back to near the neutral position and then turned in the opposite direction from the neutral position. However, the required drive torque TtgF before processing by the rate limit determination unit 140 at this time decreases to zero when the steering angle θ crosses the neutral position, and then increases.

[0077] Therefore, when secondary steering is determined, if the braking and driving force applied to the front and rear wheels is controlled without processing in the rate limit determination unit 140, the effect of improving the stability of the vehicle 10 (i.e., the effect of accelerating the convergence of lateral acceleration) cannot be reliably obtained. In contrast, the output of the select-high processing unit 142 gradually decreases before and after the steering angle θ crosses the neutral position. Therefore, when secondary steering is determined, applying braking and driving force to the front and rear wheels based on the output of the select-high processing unit 142 can stably improve the stability of the vehicle 10 (the effect of accelerating the convergence of lateral acceleration).

[0078] Figure 14 shows the changes in steering angle θ, lateral acceleration, lateral displacement, braking and driving torque of the front wheels 11 and 12, and braking and driving torque of the rear wheels 13 and 14 when turning control is performed when the vehicle 10 changes lanes, using the block diagram configuration of Figures 12 and 13. At time t1, the steering wheel 51 is turned from the neutral position and the lane change begins.

[0079] In the primary steering state, where the steering angle θ changes from time t1 to time t2 in a direction away from the neutral position, the vehicle control unit 31 applies braking torque to the front wheels 11 and 12 and driving force to the rear wheels 13 and 14. In this braking and driving state, lateral acceleration increases, improving turning ability.

[0080] From time t2, the steering wheel 51 is turned back to the neutral position. At this time, the vehicle control unit 31 applies drive torque to the front wheels 11 and 12 and braking torque to the rear wheels 13 and 14 based on the judgment of secondary steering.

[0081] At time t3, the rudder angle θ returns to the neutral position, but then the rudder angle θ passes through the neutral position and changes to the opposite side. From time t3 onward, the steering angle θ changes in a direction away from the neutral position, but the vehicle control unit 31 continues to apply driving torque to the front wheels 11 and 12 and braking torque to the rear wheels 13 and 14 (i.e., it makes decisions regarding secondary steering). Here, when the steering angle θ crosses the neutral position, the function of the rate limit determination unit 140 described above prevents a decrease in the braking and driving force applied to the front and rear wheels, thereby maximizing the effect of improving stability performance through the continuation of secondary steering decisions.

[0082] The flowchart in Figure 15 shows the turning control process common to the second and third embodiments, which applies braking and driving torque to the front and rear wheels based on the determination of primary and secondary steering. In step S201, the vehicle control unit 31 obtains information on the steering angle θ, in step S202 it differentiates the steering angle θ to obtain the steering angular velocity Δθ, and in step S203 it obtains the absolute value |Δθ| of the steering angular velocity Δθ.

[0083] Furthermore, in step S204, the vehicle control unit 31 acquires information on the vehicle speed V. Then, in step S205, the vehicle control unit 31 determines whether the absolute value of the steering angular velocity Δθ ​​|Δθ| and the vehicle speed V satisfy the conditions for performing turning control, or in other words, whether or not zero has been set as the braking / driving torque T corresponding to the absolute value of the steering angular velocity Δθ ​​|Δθ| and the vehicle speed V at the present time.

[0084] If the absolute value of the steering angular velocity Δθ ​​|Δθ| and the vehicle speed V do not satisfy the conditions for performing cornering control (in other words, if the braking and driving torque T is zero), the vehicle control unit 31 decides in step S206 not to perform cornering control, that is, not to apply braking and driving force to the front wheels 11, 12 and the rear wheels 13, 14. On the other hand, if the absolute value of the steering angular velocity Δθ ​​|Δθ| and the vehicle speed V satisfy the conditions for implementing turning control (in other words, if the braking and driving torque T is not zero), the vehicle control unit 31 proceeds to step S209.

[0085] In step S209, the vehicle control unit 31 calculates the required drive torque Ttg (Ttg = T × G2 × G3) by multiplying the absolute value of the steering angular velocity Δθ ​​at the current time |Δθ| and the torque T corresponding to the vehicle speed V by the respective gains G2 and G3. In step S207, the vehicle control unit 31 sets a second gain G2 based on the steering angle θ, and in step S208, it sets a third gain G3 based on the brake operation amount. Then, in step S209, the vehicle control unit 31 uses these gains G2 and G3 to determine the required drive torque Ttg.

[0086] Next, in step S210, the vehicle control unit 31 limits the requested braking torque Ttg so as not to exceed the upper limit of the vehicle control system 1. In the next step S211, the vehicle control unit 31 determines whether to perform primary steering or secondary steering based on the absolute value |θ| and the derivative value Δ|θ| of the steering angle θ, etc. In other words, it determines whether to apply braking force to the front wheels 11 and 12 and driving force to the rear wheels 13 and 14, or to apply driving force to the front wheels 11 and 12 and braking force to the rear wheels 13 and 14. Then, in step S212, the vehicle control unit 31 outputs a control command to apply braking and driving force to the front and rear wheels based on the determination of primary steering, secondary steering, and the calculation result of the required braking and driving torque Ttg.

[0087] Here, the vehicle control unit 31, when the steering wheel 51 is turned in either the left or right direction from the neutral position (in other words, turned further), sets the system to apply braking force to the front wheels 11 and 12 and driving force to the rear wheels 13 and 14 based on the required braking torque Ttg during primary steering. On the other hand, when the steering wheel 51 is turned in the opposite direction after the primary steering input (in other words, in the reverse steering state), the vehicle control unit 31 sets the system to apply driving force to the front wheels 11 and 12 and braking force to the rear wheels 13 and 14 based on the required braking torque Ttg during the secondary steering input. In addition, in the third embodiment, when the vehicle control unit 31 is steered to the opposite side beyond the neutral position after being turned back, it continues to make a judgment on secondary steering and continues to apply driving force to the front wheels 11 and 12 and braking force to the rear wheels 13 and 14 both before and after the neutral position.

[0088] By the way, in the torque map shown in Figure 4, as mentioned above, the first threshold THV1, which is the condition for the vehicle speed V at which turning control intervenes, can be set to 40 km / h, and the first threshold THθ1, which is the condition for the absolute value |Δθ| of the steering angular velocity Δθ ​​at which turning control intervenes, can be set to 50 deg / s. In this case, when the vehicle 10 is traveling at 60 km / h and the steering wheel 51 is turned at 60 deg / s, the vehicle control unit 31 performs a control step of applying braking force to the front wheels 11 and 12 and driving force to the rear wheels 13 and 14. In other words, when the vehicle 10 is traveling at 60 km / h and the steering wheel 51 is turned at 60 deg / s, braking force is applied to the front wheels 11 and 12 and driving force is applied to the rear wheels 13 and 14, which constitutes an embodiment of the present invention.

[0089] Furthermore, when the steering wheel 51 is turned at 70 degrees / second, the vehicle control unit 31 will perform a control step that increases the braking force applied to the front wheels 11 and 12 and the driving force applied to the rear wheels 13 and 14 compared to when the steering wheel is turned at 60 degrees / second. In other words, the fact that the braking force applied to the front wheels 11 and 12 and the driving force applied to the rear wheels 13 and 14 are greater when the steering wheel 51 is turned at 70 deg / s than when it is turned at 60 deg / s means that, at least between 60 deg / s and 70 deg / s, a control step is executed in which the braking and driving force applied to the front and rear wheels increases as the steering angular velocity increases.

[0090] Furthermore, when the vehicle 10 is traveling at 60 km / h and the steering wheel 51 is turned clockwise at 60 deg / s, and then turned back counterclockwise at 60 deg / s, the vehicle control unit 31 performs a control step in which it applies driving force to the front wheels 11 and 12 and braking force to the rear wheels 13 and 14. In other words, when the vehicle 10 is traveling at 60 km / h, and the steering wheel 51 is turned clockwise at 60 degrees / s, and then turned back counterclockwise at 60 degrees / s, the application of driving force to the front wheels 11 and 12 and braking force to the rear wheels 13 and 14 constitutes an embodiment of the present invention.

[0091] The technical concepts described in the above embodiments can be used in appropriate combinations, as long as no contradictions arise. Furthermore, although the contents of the present invention have been specifically described with reference to preferred embodiments, it will be obvious to those skilled in the art that various modifications can be taken based on the basic technical concept and teachings of the present invention.

[0092] For example, at least one of the drive actuators that apply driving force to the front wheels 11 and 12 and the drive actuators that apply driving force to the rear wheels 13 and 14 can be an internal combustion engine. Furthermore, the braking force applied to the wheels for turning control can be replaced with frictional braking force from brake actuators 15, 16, 17, and 18, instead of regenerative braking force from the motor. However, when regenerative braking is used in turning control, responsiveness and control performance can be improved compared to when friction braking is used.

[0093] Furthermore, in the third embodiment, the vehicle control unit 31 defines a period for continuing the decision to perform secondary steering based on the time elapsed since the steering angle θ was returned to near the neutral position. However, the decision to continue can be canceled before the set time is reached, based on the steering angle θ, steering angular velocity Δθ, etc. For example, when the vehicle control unit 31 is continuing to make a decision on secondary steering, it can switch from making a decision on secondary steering to making a decision on primary steering when the absolute value of the steering angle θ exceeds a set value, or when the steering angular velocity in the direction away from the neutral position exceeds a set value.

[0094] Furthermore, in setting the third gain G3 based on the brake operation amount, the vehicle control unit 31 can set the third gain G3 to 1.0 when the brake operation amount is less than or equal to a set value, and set the third gain G3 to zero when the brake operation amount exceeds a set value. In other words, the vehicle control unit 31 can switch the turning control on or off (in other words, whether to intervene or not) by comparing the amount of brake operation with a set value.

[0095] Furthermore, the vehicle control unit 31 can perform the turning control of the first embodiment in emergency avoidance mode, such as when the vehicle 10 is avoiding an obstacle, and can perform turning control that reverses braking and driving based on the primary steering and secondary steering judgments of the second or third embodiment when it is not in emergency avoidance mode. This is because, in emergency evasion mode, turning performance is more important than stability performance.

[0096] Furthermore, in the above embodiment, the vehicle control unit 31 corresponds to the vehicle control device that performs turning control, but a control unit that controls braking, such as the brake control unit 32, or a control unit that controls driving, such as the motor inverters 72 and 74, can also be the main entity that performs turning control. Furthermore, the calculation processing for rotation control can be shared among multiple control units. [Explanation of symbols]

[0097] 10...Vehicle, 11,12...Front wheels, 13,14...Rear wheels, 31...Vehicle control unit (vehicle control device, control unit), 51...Steering wheel, 71...Front motor (front electric motor, front brake drive system), 73...Rear motor (rear electric motor, rear brake drive system)

Claims

1. A vehicle control device provided in a vehicle, comprising a front brake drive device that applies braking and driving force to the front wheels of the vehicle, and a rear brake drive device that applies braking and driving force to the rear wheels of the vehicle, The control unit of the aforementioned vehicle control device is When the steering wheel of the aforementioned vehicle is turned in either the left or right direction from the neutral position, during primary steering, Based on the vehicle's speed and a physical quantity relating to the vehicle's steering angle, the first braking force generated by the front brake / drive system and the first driving force generated by the rear brake / drive system are determined. Outputting a first control command that generates the first braking force and the first driving force, Vehicle control system.

2. A vehicle control device according to claim 1, The control unit is, After the primary steering, during secondary steering, when the steering wheel is turned in the other direction, Based on the aforementioned speed and the physical quantity relating to the steering angle, the second driving force generated by the front brake drive system and the second braking force generated by the rear brake drive system are determined. Outputs a second control command that generates the second driving force and the second braking force. Vehicle control system.

3. A vehicle control device according to claim 1, The control unit is, Based on the aforementioned speed, the rudder angular velocity among the physical quantities relating to the rudder angle, and the rudder angle among the physical quantities relating to the rudder angle, the first braking force and the first driving force are determined. Vehicle control system.

4. A vehicle control device according to claim 3, The control unit is, If the speed is less than a predetermined first speed threshold and the steering angular velocity is less than a predetermined first steering angular velocity threshold, the first braking force and the first driving force are output as zero. Vehicle control system.

5. A vehicle control device according to claim 4, The control unit is, If the speed is greater than the first speed threshold and less than a predetermined second speed threshold that is greater than the first speed threshold, the greater the speed, the greater the first braking force and the first driving force. If the speed exceeds the second speed threshold, the greater the speed, the smaller the first braking force and the first driving force. If the steering angular velocity is greater than the first steering angular velocity threshold and less than a predetermined second steering angular velocity threshold which is greater than the first steering angular velocity threshold, the greater the steering angular velocity, the greater the first braking force and the first driving force. If the steering angular velocity exceeds the second steering angular velocity threshold, the greater the steering angular velocity, the smaller the first braking force and the first driving force. Vehicle control system.

6. A vehicle control device according to claim 3, The control unit is, The larger the steering angle, the greater the first braking force and the first driving force. Vehicle control system.

7. A vehicle control device according to claim 3, The control unit is, The greater the frictional braking force based on the amount of brake operation of the vehicle, the smaller the first braking force and the first driving force. Vehicle control system.

8. A vehicle control device according to claim 3, The control unit is, The first braking force and the first driving force are determined by applying predetermined limitations imposed by the vehicle's system. Vehicle control system.

9. A vehicle control device according to claim 1, The control unit is, The output is made by making the magnitude of the first braking force equal to the magnitude of the first driving force. Vehicle control system.

10. A vehicle control device according to claim 1, The control unit is, The magnitude of the first braking force and the magnitude of the first driving force are distributed in a predetermined distribution ratio and output. Vehicle control system.

11. A vehicle control device according to claim 2, The control unit is, The second driving force and the second braking force are determined by selecting a high value for the braking force based on the speed, the physical quantity related to the steering angle, and a braking force limit value that limits the change in the braking force. Vehicle control system.

12. A vehicle control device according to claim 1, The front brake / drive system is a front electric motor, and the rear brake / drive system is a rear electric motor. Vehicle control system.

13. A vehicle control method performed by a control unit mounted on a vehicle, When the vehicle is traveling at 60 km / h, and the steering wheel of the vehicle is turned at a rate of 60 degrees / second, The system applies braking force to the front wheels of the vehicle and driving force to the rear wheels of the vehicle. Vehicle control method.

14. A vehicle control method according to claim 13, When the steering wheel is turned at 70 degrees / s, the braking force applied to the front wheels of the vehicle and the driving force applied to the rear wheels of the vehicle are increased compared to when the steering wheel is turned at 60 degrees / s. Vehicle control method.

15. A vehicle control method performed by a control unit mounted on a vehicle, When the vehicle is traveling at 60 km / h, and the steering wheel of the vehicle is turned clockwise at 60 degrees / s, and then the steering wheel is turned back counterclockwise at 60 degrees / s, The system applies driving force to the front wheels of the vehicle and braking force to the rear wheels of the vehicle. Vehicle control method.

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