JP5082402B2 - Vehicle steering control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress a driver's sense of incongruity caused by fluctuation of a forward/backward force difference between right and left wheels. <P>SOLUTION: During &mu; split control, the maximum value MSm of an absolute value of a stabilization moment MS including a component of the forward/backward force difference &Delta;FX is stored, and based on the maximum value MSm, a correction steering target value (correction torque target value Tms) is determined. Thus, when the &mu; split control is executed, even if an increasing/decreasing cycle of forward/backward force FX** of the right and left wheels varies and the forward/backward force difference &Delta;FX is periodically increased/decreased, fluctuation of the correction steering target value Tms along with the increase/decrease can be prevented. As a result, this can suppress effects on a steering wheel by the fluctuation and can prevent a driver from having a sense of incongruity. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a vehicle steering control device that executes counter steer control that reduces a vehicle deflection caused by a difference in longitudinal force between left and right wheels by counter-steering in a direction opposite to the deflection direction. .

  Slip suppression control (such as anti-skid control (ABS control), traction control (TCS control), etc.) that suppresses wheel slip while the vehicle is traveling on a road surface (hereinafter referred to as a μ-split road surface) with different friction coefficients on the left and right road surfaces ( (Hereinafter referred to as “μ split control”), the difference (ABS) between the front and rear forces of the left and right wheels (the friction force in the acceleration / deceleration direction generated between the road surface and the tire, also referred to as braking / driving force). A braking force difference occurs in the case of control, and a driving force difference in the case of TCS control. A yaw moment that deflects the vehicle due to the difference between the longitudinal forces (hereinafter referred to as a longitudinal force difference-induced yaw moment) is generated.

  In order to suppress the deflection of the vehicle due to the yaw moment due to the longitudinal force difference, the steering wheel is operated in the direction opposite to the direction of deflection of the vehicle, so that the steering angle of the steering wheel is directed in the direction opposite to the direction of deflection of the vehicle. Therefore, it is necessary to reduce (cancel) the yaw moment resulting from the difference in longitudinal force. Such an operation for correcting the steering angle of the steering wheel in the direction opposite to the deflection direction of the vehicle is called a counter steer operation. In order to perform this counter steer operation, driving skill is required.

  On the other hand, Patent Document 1 uses a steering gear ratio variable mechanism (hereinafter referred to as VGRS) that adjusts the ratio of the steering angle of the steering wheel to the rotation angle of the steering wheel (steering gear ratio) by driving an electric motor. In the apparatus that performs the steering control by the steering angle control, the counter steer operation can be automatically executed without the driver's steering wheel operation. Specifically, a correction target value for the steering angle of the steering wheel is determined based on the difference in the longitudinal force between the left and right wheels, and the steering angle of the steering wheel is corrected in the direction opposite to the vehicle deflection direction by the correction target value. The

In Patent Document 2, an electric power steering mechanism (hereinafter referred to as EPS) that automatically adjusts steering torque of a steering wheel by a driver by driving an electric motor is used to perform steering control by steering torque control. In the apparatus, a device that prompts a driver to perform a counter steer operation by a steering operation is described. Specifically, the correction target value of the steering torque is determined based on the difference between the front and rear forces of the left and right wheels, and the steering torque is corrected by the correction target value in a direction that prompts the steering wheel operation in the direction corresponding to the counter steer operation. .
JP 2005-255035 A JP 2004-352030 A

  In general, in ABS control and TCS control, wheel braking torque and driving torque periodically increase and decrease to suppress wheel slip. Thereby, the longitudinal force of the wheel also periodically increases and decreases.

  For this reason, on the μ split road, the friction force between the road surface and the left wheel FL, RL and the right wheel FR, RR is different. Therefore, when the μ split control is executed, the longitudinal force increase / decrease cycle of the left and right wheels is different. The difference can also increase or decrease periodically.

  Therefore, as in the steering angle control and the steering torque control described in Patent Documents 1 and 2, the steering angle correction amount or the steering torque correction amount of the steering wheel is determined based on the difference in the longitudinal force between the left and right wheels. In this case, the correction amount may vary, and as a result, the steering angle of the steering wheel or the steering torque may also vary. For this reason, there is a problem that the steering wheel is directly affected and the driver feels uncomfortable.

  In view of the above, the present invention provides a steering control device for a vehicle that executes steering control (hereinafter referred to as corrected steering control) that suppresses deflection of the vehicle due to a yaw moment caused by a difference in longitudinal force between the left and right wheels. The object is to suppress the driver's uncomfortable feeling caused by fluctuations in the longitudinal force difference.

  In order to achieve the above object, according to the first aspect of the present invention, the first calculating means (50h, S110) for calculating the longitudinal force (FX **) of the wheels (FL to RR) and the longitudinal force (FX **). ) Based on the second calculation means (50i, S115) for calculating the front-rear force difference (ΔFX) between the left and right wheels, and the maximum value (MSm, ΔFXm) of the state quantity (ΔFX, MS) including the front-rear force difference (ΔFX) Storage means (50j, S125), third calculation means (50k, S155) for calculating a corrected steering target value (Tms, δms) based on the maximum values (MSm, ΔFXm), a corrected steering target value ( Drive means (50b) for outputting a control instruction value based on (Tms, δms).

  Thus, the maximum values (MSm, ΔFXm) of the state quantities (ΔFX, MS) including the longitudinal force difference (ΔFX) are stored, and the corrected steering target value (MSm, ΔFXm) is stored based on the stored maximum values (MSm, ΔFXm). Tms, δms) is calculated. Accordingly, when the μ split control is executed, even if the increase / decrease cycle of the front / rear force (FX **) of the left and right wheels is different and the front / rear force difference (ΔFX) increases / decreases periodically, the corrected steering target accordingly It is possible to prevent the values (Tms, δms) from fluctuating. Therefore, the influence on the steering wheel due to this can be suppressed, and the driver can be prevented from feeling uncomfortable.

  In this case, as shown in claim 2, the fourth calculation means (50m, S145) for calculating the duration (tms) after the start of the μ split control, and the predetermined duration (tms) are predetermined. When the time (τk) or more is reached, correction means (50q, ΔFXms) for calculating the maximum values (MSms, ΔFXms) corrected so as to decrease the maximum values (MSm, ΔFXm) stored in the storage means (50j, S125) to zero. S160), and the third calculation means (50k, S155) calculates the corrected steering target value (Tms, δms) based on the maximum values (MSms, ΔFXms) corrected by the correction means (50q, S160). It is preferable.

  In this way, when the μ-split control is continued for a predetermined time (τk), if the corrected steering control is terminated, it is difficult for the driver to deal with the sudden front-rear force difference-induced yaw generated immediately after the start of the μ-split control. Counter steer operation corresponding to the moment can be performed. Further, it is possible to prevent the correction steering control from being continued excessively until after the return operation is performed.

  Further, as shown in claim 3, the determination means (50p, S130) for detecting the operation state of the operation member (60) for operating the longitudinal force by the driver and determining that the return operation has been performed. When the return operation is performed, correction means (50q, ΔFXms) for calculating the maximum values (MSms, ΔFXms) corrected so as to decrease the maximum values (MSm, ΔFXm) stored in the storage means (50j, S125). S135) is preferably provided.

  As described above, when the return operation is performed, the counter steering operation corresponding to the return operation can be performed by correcting the maximum values (MSm, ΔFXms) and obtaining the corrected steering target values (Tms, δms). This can prevent the driver from feeling more uncomfortable.

  In this case, as shown in claim 4, the correcting means (50q, S135) is stored in the storage means (50j, S125) when the operation member (60) returns to the position before the operation and the return operation is completed. Can be modified to reduce the maximum value (MSm, ΔFXm) to zero.

  Furthermore, as shown in claim 5, the difference between the maximum value (MSm, ΔFXm) stored in the storage means (50j, S125) and the state quantity (ΔFX, MS) including the longitudinal force difference (ΔFX) is a predetermined value. The comparison means (50t) for comparing whether or not (Km) is exceeded, the counting means (50u) for counting the duration when it is determined that the difference exceeds the predetermined value, When the duration time exceeds a predetermined time (τm), the maximum values (MSms, ΔFXms) corrected so as to decrease the maximum values (MSm, ΔFXm) stored in the storage means (50j, S125) are calculated. It is preferable to provide correction means (50q, S135).

  As described above, the period in which the difference between the maximum value (MSm, ΔFXm) and the state quantity (ΔFX, MS) including the longitudinal force difference (ΔFX) is equal to or greater than the predetermined value (Km) continues for the predetermined time (τm) or longer. In this case, by correcting the maximum values (MSm, ΔFXm), even if the longitudinal force difference (ΔFX) decreases with the change in the road surface friction coefficient, the corresponding maximum values (MSm, ΔFXm) are corrected. Yes.

  The invention described in claim 6 further includes limiting means (50r, S140, S165) for setting a limit on the amount of time change of the maximum value (MSms) after correction by the correcting means (50q, S135, S160). It is characterized by.

  In this way, a limit is set for the amount of time change of the maximum values (MSm, ΔFXms). For this reason, the fluctuation | variation of a steering operation member (21) is relieve | moderated and it becomes possible to suppress the discomfort to a driver | operator.

  As described above, claims 1 to 6 are inventions related to storing the maximum value of the state quantity (ΔFX, MS) including the longitudinal force difference (ΔFX), but as shown in claims 7 to 12, A corrected steering target value (Tms, δms) is obtained based on the state quantity (ΔFX, MS) including the longitudinal force difference (ΔFX), and the maximum value (Tmsm, δmsm) of the corrected steering target value (Tms, δms). As for the invention in which the final corrected steering target value (Tmsa, δmsa) is obtained by storing the same, the same means as in the first to sixth aspects can be employed to obtain the same effect. Can do.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
FIG. 1 is a schematic diagram showing an overall configuration of a motion control mechanism 10 of a vehicle 1 provided with a steering control device according to a first embodiment of the present invention. Hereinafter, the configuration of the motion control mechanism 10 of the vehicle 1 will be described with reference to this figure, and details of the steering control device according to the embodiment of the present invention will be described.

  As shown in FIG. 1, the motion control mechanism 10 includes a steering control mechanism 20, a brake control mechanism 30, various sensors 41 to 46, and an electronic control device (hereinafter referred to as ECU) 50.

  The steering control mechanism 20 of the present embodiment performs steering control by steering torque control. As shown in FIG. 1, the steering wheel 21, the steering shaft 22, the steering torque sensor 23, the EPS 24, the steering gear mechanism 25, the steering A link mechanism 26, a steering angle sensor 28, and the like are provided, and the angle (steering angle) of the front wheels FL and FR serving as steering wheels with respect to the vehicle center line is adjusted.

  The steering wheel 21 corresponds to a steering operation member that is operated by the driver. When the steering wheel 21 is operated by the driver, for example, the steering shaft 22 is rotated via a steering column (not shown). The steering angle of the steering wheel 21 by the driver is detected by a steering angle sensor 28.

  The steering shaft 22 transmits the steering operation of the driver as a steering force (steering torque). The steering shaft 22 is divided into two parts, a steering wheel 21 side portion (hereinafter referred to as an upper shaft) 22a and a steering gear mechanism 25 side portion (hereinafter referred to as a lower shaft) 22b. The upper shaft 22a includes a driver. The torque generated by the above operation is transmitted as it is, and the torque obtained by adding the torque transmitted to the upper shaft 22a and the assist force of the motor 24a (described later) provided in the EPS 24 is transmitted to the lower shaft 22b.

  The steering torque sensor 23 detects the steering torque ST acting on the steering wheel 21, and is provided in the upper shaft 22a to generate an output signal corresponding to the steering torque ST.

  The EPS 24 includes a motor 24a and a speed reduction mechanism 24b. When the motor 24a is driven by a motor control signal from the ECU 50, an assist force is applied to the lower shaft 22b via the speed reduction mechanism 24b. A handle shaft torque is generated in the lower shaft 22b. The EPS 24 generates a handle shaft torque by adding an assist force by the motor 24a to the torque generated in the upper shaft 22a.

  The steering gear mechanism 25 is composed of a combination of gears, for example, a rack and pinion type, and a rotation angle is given to the pinion gear 25a by the rotation of the lower shaft 22b. Is converted into a reciprocating motion of the rack 25b. That is, the handle shaft torque transmitted to the lower shaft 22b, that is, the rotational force is converted into the reciprocating force of the rack 25b.

  The steering link mechanism 26 transmits the force transmitted from the steering gear mechanism 25 to the knuckle arm 26b via the tie rod 26a and the like. As a result, the left and right front wheels FL and FR that are the steering wheels are steered in the same direction.

The brake control mechanism 30 includes an anti-skid control (hereinafter referred to as ABS control), a traction control (hereinafter referred to as TCS control), a skid prevention control (hereinafter referred to as ESC (hereinafter referred to as ESC)) that includes a plurality of solenoid valves, reservoirs, pumps, and motors. Each wheel cylinder (hereinafter referred to as W / C) 32 * provided in each wheel FL, FR, RL, and RR using a known brake fluid pressure control actuator 31 that executes electronic stability control). The pressure generated in * (hereinafter referred to as W / C pressure) is controlled. As the brake hydraulic pressure control actuator 31, either a hydraulic brake system that generates W / C pressure by hydraulic pressure or an electric brake system such as a brake-by-wire that generates W / C pressure electrically can be adopted. Since it is a known one, the specific structure of the brake fluid pressure control actuator 31 is omitted here.

  In addition, “**” attached to the reference symbol is a subscript meaning each of the wheels FL to RR, “FL” is the left front wheel, “FR” is the right front wheel, “RL” is the left rear wheel, “RR” means the right rear wheel. For example, W / C32 ** means W / C32FL to 32RR.

  In such a brake control mechanism 30, when ABS control, TCS control, and ESC control are not executed (during normal braking), brake fluid pressure corresponding to the operation of the brake pedal 60 is generated in each W / C 32 **. Let As a result, the brake pads are pressed against the disc rotor 34 ** by the calipers 33 **, and braking torque is generated. When the ABS control, TCS control or ESC control is executed, the brake fluid pressure control actuator 31 adjusts the pressure of the W / C 32 ** to be controlled independently of the operation of the brake pedal 60, and the braking torque is Adjusted.

  The various sensors 41 to 46 generate detection signals used for various controls such as ABS control, TCS control, and ESC control. Specifically, a wheel speed sensor 41 ** and a W / C pressure sensor 42 ** are provided for each of the wheels FL to RR, a yaw rate sensor 43, a longitudinal acceleration sensor 44, a lateral acceleration sensor 45, pedal operation A quantity sensor 46 is provided. Detection signals of these various sensors 41 to 46 are input to the ECU 50.

  The ECU 50 receives the detection signal of the steering torque sensor 23, generates a motor control signal indicating a control instruction value according to the detection signal, receives the detection signals of the various sensors 41 to 46, and controls the brake fluid pressure accordingly. The actuator 31 is driven to perform μ split control in addition to normal ABS control, TCS control, and ESC control, and to correct the control instruction value of the motor control signal according to the control state of the μ split control. In this way, the ECU 50 performs the steering control that outputs the motor control signal to adjust the steering (steering force) of the left and right front wheels FL and FR that become the steering wheels. In the present embodiment, this steering control is performed using the EPS 24. This is performed by the steering torque control used. In the present embodiment, one ECU 50 that performs various controls in an integrated manner is shown, but a plurality of control units mounted on the vehicle 1, such as a braking / driving force control unit, a front wheel steering angle control unit, a power A plurality of control units such as a steering control unit and a power train control unit may be combined and connected by a communication bus.

  FIG. 2 is a diagram showing a block configuration of a part related to steering control (steering torque control) described in the present embodiment in the ECU 50 (specifically, CPU). With reference to this figure, each control block will be described.

  As shown in FIG. 2, the ECU 50 includes a reference target value determining unit 50a and a driving unit 50b.

  The reference target value determining means 50a obtains a reference target value for adjusting the turning of the steering wheels FL and FR based on the operation of the steering operation member (steering wheel 21) by the driver. Specifically, the reference target value determining means 50a is based on a map or a function expression showing the vehicle body speed, the steering torque of the steering wheel 21, and the relationship between these and the reference torque target value Ts corresponding to the reference target value. Then, a reference torque target value Ts is obtained. The reference torque target value Ts is a target value of the output torque of the motor 24a for performing vehicle speed sensitive power steering control for reducing the driver's steering operation force, and is set to a smaller value as the vehicle body speed increases. . The vehicle body speed is obtained by a known method based on each wheel speed Vw ** obtained from the detection signal of the wheel speed sensor 41 **, and the steering torque is obtained based on the detection signal of the steering torque sensor 23. .

  The driving unit 50b outputs a motor control signal to the motor 24a so that the output of the motor 24a coincides with the reference torque target value Ts during normal operation (when the correction steering control is not operated), and steering torque control is performed. I do. When it is necessary to perform the correction steering control, a correction torque target value Tms corresponding to a correction steering target value described later is calculated. Based on the reference torque target value Ts and the corrected torque target value Tms (the corrected torque target value Tms is added to the reference torque target value Ts), the final steering torque target value (the output target value of the motor 24a) Is required. This output target value is converted into a value (motor control signal) corresponding to the motor control command value, and the converted motor control signal is output to the motor 24a.

  Further, the ECU 50 includes an actual motion calculation means 50c, a target motion calculation as means for obtaining a corrected steering target value for executing the correction steering control corresponding to the μ split control (the steering control for reducing the longitudinal force difference-induced moment). Means 50d, comparison means 50e, stabilization moment calculation means 50f, ABS / TCS control means 50g, longitudinal force calculation means 50h, longitudinal force difference calculation means 50i, maximum value storage means 50j and corrected steering target value calculation means 50k are provided. ing.

  The actual motion calculation means 50c calculates a momentum VMa actually generated in the vehicle 1 (hereinafter referred to as an actual momentum). Here, the “momentum” is a state quantity that represents the turning motion of the vehicle, and is a state quantity that is calculated using values corresponding to the yaw rate, the lateral acceleration, the vehicle body slip angle, and the vehicle body slip angular velocity. For example, an actual yaw rate actually generated (hereinafter referred to as an actual yaw rate) is calculated based on the detection signal of the yaw rate sensor 43.

  The target motion calculation means 50d calculates a target exercise amount VMt (hereinafter referred to as a target exercise amount) of the vehicle 1, and calculates a state amount in the same dimension as the actual exercise amount. For example, when the momentum is a yaw rate, a target yaw rate (hereinafter referred to as a target yaw rate) obtained by a known method is calculated based on the detection signal of the steering angle sensor 28 and the vehicle body speed.

  Here, the target of the actual exercise amount VMa and the target exercise amount VMt is the yaw rate, but other state quantities (for example, a vehicle body slip angle, etc.) well-known as those used for ESC control may be used. . Further, in the case of the EPS 24, since the upper shaft 22a and the lower shaft 22b are connected, the steering angle of the steering wheel 21 detected by the steering angle sensor 28 is in the traveling direction intended by the driver, or the counter steer operation is performed. It is difficult to determine whether it is reflected. For this reason, the target momentum can be set to zero assuming that the vehicle 1 is traveling straight. It is also possible to obtain the target momentum based on the steering angle of the steering wheel 21 immediately before the μ split control is started.

  The comparison unit 50e calculates a deviation ΔVM between the actual exercise amount VMa and the target exercise amount VMt. The stabilization moment calculating means 50f calculates the stabilization moment MS using the deviation ΔVM obtained by the comparison means 50e and the longitudinal force difference ΔFX obtained by the longitudinal force difference calculating means described later. Specifically, the stabilization moment MS is obtained by substituting the deviation ΔVM and the longitudinal force difference ΔFX into the calculation formula shown in Formula 1. In Equation 1, G1 and G2 are predetermined coefficients.

(Equation 1)
MS = G1 · ΔFX + G2 · ΔVM Equation 1
The ABS / TCS control means 50g obtains the wheel speed Vw ** and the vehicle body speed (estimated vehicle body speed) based on the detection signal from the wheel speed sensor 41 **, and obtains the slip ratio for each wheel FL to RR. ABS control and TCS control are executed based on this slip ratio. In the ABS control, wheel slip is suppressed by adjusting the braking torque by reducing, holding, and increasing the W / C pressure of the target wheel by the brake fluid pressure control actuator 31. In the TCS control, the driving torque is adjusted by increasing, holding, or reducing the W / C pressure of the driving wheel by the brake hydraulic pressure control actuator 31, or by adjusting the output of the engine (not shown). Suppress wheel slip. These ABS control and TCS control methods are well known and will not be described here, but the ABS / TCS control means 50g uses the W / C pressure of each wheel FL to RR during ABS control or TCS control. Since this control target value is obtained, this is transmitted to the longitudinal force calculating means 50h.

  In the longitudinal force calculating means 50h, the longitudinal force FX ** of each wheel FL to RR is calculated. The longitudinal force is a frictional force in the acceleration / deceleration direction generated between the road surface and the tire as described above, that is, a braking / driving force. Specifically, each wheel is obtained by a known method of obtaining the braking torque of each of the left and right wheels FL to RR based on the control target value of the W / C pressure of each wheel FL to RR during ABS control or TCS control. A longitudinal force FX ** of FL to RR is obtained.

  As for the longitudinal force FX **, in addition to this, the left and right wheels FL to RR determined using the W / C pressure of each wheel FL to RR detected from the detection signal of the W / C pressure sensor 42 **. Braking torque, driving torque of each wheel FL to RR obtained from engine driving torque (not shown), acceleration / deceleration of each wheel FL to RR obtained by differentiating wheel speed Vw **, and rotational motion of each wheel FL to RR It may be obtained from the equation, the operating state of the brake fluid pressure control actuator 31 (indicated current value to the electromagnetic valve), etc., and may be obtained by any known method.

  The longitudinal force difference calculation means 50i is based on the difference between the longitudinal forces FX ** of the left wheels FL, RL and the right wheels FR, RR based on the longitudinal forces of the wheels FL to RR determined by the longitudinal force calculation means 50h ( Hereinafter, ΔFX) is calculated. On the μ split road surface, the friction coefficients of the left and right road surfaces are different. Therefore, when the μ split control is executed, the front / rear forces of the left wheel FL, RL and the right wheel FR, RR are different from each other. A difference ΔFX occurs. This longitudinal force difference ΔFX is a physical quantity corresponding to the magnitude of the longitudinal force difference-induced yaw moment.

  For example, the front / rear force difference ΔFX may be a value obtained by subtracting the sum of the front / rear forces FXFL, FXRL of the left front / rear wheel FL, RL from the sum of the front / rear forces FXFR, FXRR of the right front / rear wheels FR, RR. The sign of the longitudinal force difference ΔFX changes in the clockwise direction and the counterclockwise direction as viewed from above the vehicle, but either direction may be positive or negative. The longitudinal force difference ΔFX calculated by the longitudinal force difference calculating means 50i is transmitted to the stabilizing moment calculating means 50f, and the stabilizing moment MS is obtained.

  The maximum value storage means 50j stores the maximum value MSm of the absolute value of the stabilization moment MS together with the positive and negative signs of the stabilization moment MS. That is, when the μ split control is executed, the increase / decrease cycle of the longitudinal force FX ** of the left and right wheels is different, and the longitudinal force difference ΔFX can also be periodically increased / decreased. Therefore, by storing the maximum value MSm of the absolute value of the stabilization moment MS including the component of the longitudinal force difference ΔFX, it is possible to store the value when the longitudinal force difference ΔFX has increased most. FIG. 3 is a timing chart showing changes in the maximum value MSm stored with respect to changes in the stabilization moment MS. As shown in this figure, even if the stabilization moment MS changes, the maximum value MSm is stored, so that the effect of fluctuation of the stabilization moment MS on the periodic increase / decrease in the longitudinal force difference ΔFX during μ split control can be reduced. It is possible to memorize values that are not received. Further, as shown in the figure, when the stabilization moment MS is increased by the additional operation of the brake pedal 60 or the accelerator pedal, the maximum value MSm is also newly stored, so that it is possible to cope with the additional operation.

  The corrected steering target value calculating means 50k calculates a corrected torque target value Tms, which becomes a corrected steering target value, based on the maximum value MSm of the absolute value of the stabilizing moment MS and the sign of the stabilizing moment MS. Specifically, the corrected torque target value Tms is calculated using a map showing the relationship between the maximum value MSm and the corrected torque target value Tms stored in advance in the ROM or the like of the ECU 50. For example, this map is represented by a graph as shown in FIG. 4, and the larger the maximum value MSm, the larger the corrected torque target value Tms. Then, when the corrected torque target value Tms is obtained in this way, the final steering torque target value is obtained by adding the reference torque target value Ts and the corrected torque target value Tms in the driving means 50b. A motor control signal indicating the corresponding control instruction value is output to the motor 24a.

  Further, the ECU 50 is provided with duration calculation means 50m, driving operation calculation means 50n, return operation determination means 50p, maximum value correction means 50q, and restriction means 50r. By these means, the limit value of the corrected steering target value is set when the corrected steering control is terminated.

  The duration calculation means 50m calculates the duration tms after the start of the μ split control. Immediately after the start of μ-split control, a yaw moment due to a sudden front-rear force difference is generated, so it is difficult for the driver to perform a counter-steer operation following the change. It is possible for a person to perform a counter-steer operation corresponding to the change, and the correction steering control may be terminated. Therefore, the duration tms is calculated by the duration calculation means 50m so as to measure the time until the end of the correction steering control. Note that the start of μ split control can be determined from the fact that, for example, the flag set during μ split control by the ABS / TCS control means 50g is switched from the reset state to the set state.

  The driving operation calculation means 50n calculates an operation amount DS of a brake pedal 60 or an accelerator pedal (not shown) serving as a longitudinal force operation member. The operation amount of the brake pedal 60 is obtained from detection signals of a pedal operation amount sensor 46, for example, a pedaling force sensor, a stroke sensor, and a master cylinder pressure sensor. The operation amount of the accelerator pedal is obtained from detection signals from an accelerator pedal operation amount sensor, an accelerator opening sensor handled in engine control, and a throttle opening sensor.

  The return operation determination means 50p determines whether or not an operation for returning to a state before the brake pedal 60 or an accelerator pedal (not shown) is not operated (hereinafter simply referred to as a return operation) has been performed. For example, when a return operation is performed, the stabilization moment MS decreases accordingly, so it may not be preferable to use the stored maximum value MSm as it is. Therefore, whether or not the maximum value MSm needs to be corrected is determined based on whether or not a return operation has been performed.

  The maximum value correcting means 50q corrects the maximum value MSm stored in the maximum value storing means 50j based on the duration tms and the return operation determination result DSm. As described above, the correction steering control is ended when the duration tms has passed the predetermined time τk. Therefore, the maximum value correcting means 50q reduces the maximum value MSm to zero when the duration time tms has passed the predetermined time τk. Further, the maximum value correcting means 50q does not suddenly reduce the maximum value MSm to zero, but can reduce it to zero step by step as time elapses. When the return operation is performed, it is necessary to correct the maximum value MSm correspondingly. For this reason, when the return operation is performed, the maximum value MSm is corrected to be decreased. In the case of the present embodiment, the maximum value MSm is reduced to a constant ratio by multiplying the maximum value MSm by a positive coefficient K1 smaller than 1. In this way, the maximum value MSms taking into account the duration tms and the return operation are obtained by the maximum value correcting means 50q.

  The limiting unit 50r sets a limit on the time change of the maximum value MSms. The maximum value correcting means 50q performs correction to reduce the maximum value MSm. If the corrected maximum value MSms changes suddenly, it may appear in the vehicle behavior and give the driver a sense of incongruity. There is. Therefore, the amount of time change is limited so as to gradually decrease the maximum value MSms. For example, the change amount (decrease gradient) of the maximum value MSms per control cycle is limited to a predetermined value Kdown. When the change amount of the maximum value MSms is equal to or greater than the predetermined value Kdown, the final maximum value MSml is calculated by decreasing the predetermined value Kdown from the maximum value MSms every control cycle. When the continuous time tms has passed the predetermined time τk, the corrected steering target value calculation is performed even if the maximum value MSm stored in the maximum value storage means 50j is transmitted to the corrected steering target value calculation means 50k. The means 50k obtains a corrected steering control target value (corrected torque target value) using the final maximum value MSml in preference to the maximum value MSm. On the other hand, when the maximum value MSm is decreased by the return operation determination, the corrected steering target value calculation means 50k gives priority to the maximum value MSm over the maximum value MSml, and uses the maximum value MSm to correct the corrected steering control target value (correction). Torque target value) is obtained.

  FIG. 5 is a timing chart showing how the maximum value MSm changes when a predetermined time τk elapses after the μ split control is started. As indicated by the broken line in this figure, when the correction steering control is terminated, the maximum value MSm is reset to zero. In addition, there is a limit to the amount of time change of the maximum value MSm, and the maximum value MSm can be gradually decreased. For this reason, it is possible to suppress the driver from feeling uncomfortable.

  Although the maximum value storage means 50j may store the actual value MS as the maximum value MSm, the corrected steering target value deduction means 50k has a duration tms that has already passed the predetermined time τk. Prior to the maximum value MSm, the corrected steering control target value (corrected torque target value) is obtained using the maximum value MSml during the limiting process. For example, after time t1, the actual value MS (newly stored MSm) becomes larger than the maximum value MSm1 during the limit process, but the corrected steering control target value (corrected torque target value) is the maximum during the limit process. Determined based on the value MSml.

  FIG. 6 is a timing chart showing how the maximum value MSm changes when the return operation is performed. As shown in this figure, when the return operation is performed halfway, the maximum value MSm is reduced to a predetermined ratio with respect to before the return operation, and when the return operation is completely performed, the maximum value MSm is decreased to zero. . Also at this time, the amount of time change of the maximum value MSm is limited, and the maximum value MSm is gradually reduced, so that it is possible to suppress the driver from feeling uncomfortable.

  The maximum value storage unit 50j may store the actual value MS as the maximum value MSm. However, since the decrease in the maximum value MSm is caused by the return operation determination result, the corrected steering target value calculation unit 50k The maximum value MSm is prioritized over the maximum value MSml during the limiting process, and the corrected steering control daily target value (corrected torque target value) is obtained using the maximum value MSm. For example, immediately after the time point t2, the actual value MS (newly stored MSm) becomes larger than the maximum value MSml during the limit process, so the corrected steering control target value (corrected torque target value) is newly set. It is obtained based on the stored maximum value MSm.

  Next, details of the correction steering control executed by the ECU 50 configured as described above will be described. FIG. 7 is a flowchart of the correction steering control. Each process shown in this figure is executed at every predetermined control cycle, and is executed when the ignition switch is turned on, for example, and is ended when the ignition switch is turned off.

  First, in step 100, general initialization processing such as flag reset is performed, and then in step 105, signal reading processing such as reading of detection signals of the steering torque sensor 23 and various sensors 41 to 46 is performed.

  Next, in step 110, the longitudinal force FX ** of each wheel FL to RR is calculated, and in step 115, the longitudinal force difference ΔFX is calculated. The longitudinal force FX ** and the longitudinal force difference ΔFX are calculated by the above-described method by the longitudinal force calculating means 50h and the longitudinal force difference calculating means 50i.

  Subsequently, in step 120, it is determined whether the μ split control is being performed. Whether or not the μ split control is being performed is determined, for example, by checking a flag that the ABS / TCS control means 50g sets during the μ split control. Then, if an affirmative determination is made here, the routine proceeds to step 125, where the stabilization moment MS is obtained based on the longitudinal force difference ΔFX, and the maximum value MSm of the absolute value of the stabilization moment MS together with the positive and negative signs of the stabilization moment MS. Remember. The maximum value MSm is obtained and stored in the maximum value storage means 50j. This maximum value MSm is selected by selecting a larger one by comparing MAX (MS, MSm), that is, the maximum value MSm up to the previous control cycle and the stabilization moment MS obtained in the current control cycle. The larger one is updated as a new maximum value MSm.

  Further, in step 130, it is determined whether or not a return operation has been performed. This determination is performed by the return operation determination means 50p. If an affirmative determination is made here, correction is made to decrease the maximum value MSm in step 135 based on the determination result DSm. This correction is performed by the maximum value correcting means 50q. As described above, the corrected maximum value MSms is obtained by multiplying the maximum value MSm before the return operation by the coefficient K1 (a positive value smaller than 1). It is done. In step 140, a restriction process is executed. This restriction process is performed by the restriction means 50r, and a restriction is provided on the time change of the corrected maximum value MSms obtained by correcting the maximum value MSm before the return operation. Thereby, the final maximum value MSml is obtained. On the other hand, if a negative determination is made in step 130, the process proceeds to step 145 as it is.

  Thereafter, in step 145, the duration tms is counted, and then the process proceeds to step 150. Then, it is determined whether or not the duration time tms has passed the predetermined time τk. This processing is also performed by the maximum value correcting means 50q. The predetermined time τk may be a predetermined time, but in the present embodiment, the predetermined time τk is determined according to the vehicle body speed (initial speed Vxi) when the μ split control is started. FIG. 8 is a map showing the relationship between the initial speed Vxi and the predetermined time τk. This map is stored in advance in the maximum value correcting means 50q, and the predetermined time τk becomes longer as the initial speed Vxi increases. This is because when the correction steering control is performed as the μ split control starts, the time required for the correction steering becomes longer as the initial speed Vxi is larger.

  If an affirmative determination is made at step 150, the routine proceeds to step 155, where the maximum value MSm (or maximum value MSms, MSml) with the positive / negative sign stored at step 125 is converted into a torque, and a corrected torque target value Tms is calculated. To do. Specifically, Tms = MSnc (MSm), where MSnc (MSm) is a map (see FIG. 4) or a function expression using MSm as an argument, and the corrected torque target value is substituted by the maximum value MSm. Tms can be calculated.

  Further, if a negative determination is made in step 150, or if a negative determination is not made in the μ split control in step 120, the process proceeds to step 160 and the maximum value MSm is reset to zero. Then, the process proceeds to step 165 to execute a restriction process. This restriction process is performed by the restriction means 50r, and a restriction is provided on the time change of the corrected maximum value MSms obtained by correcting the maximum value MSm before the return operation. Thereby, the final maximum value MSml is obtained. On the other hand, if a negative determination is made in step 120, the process proceeds to step 165 as it is. Then, the restriction process is executed by the same method as in step 140. Thereby, the final maximum value MSml is obtained. Thereafter, the process proceeds to step 155, and the corrected torque target value Tms is obtained by performing torque conversion on the maximum value MSm (or maximum value MSms, MSml) with a positive or negative sign.

  When the corrected torque target value Tms is obtained in this way, the reference torque target value Ts and the corrected torque target value Tms are summed by the drive means 50b in another flow (not shown) to obtain the final steering torque target value. The corresponding output torque target value (output target value) of the motor 24a is obtained. Then, a motor control signal indicating a control instruction value for realizing this is output to the motor 24a, so that the correction steering control for reducing the longitudinal force difference-induced yaw moment generated during the μ split control is executed, and the driving is performed. It is possible to prompt the user to perform a counter steer operation during the μ split control.

  FIG. 9 shows a timing chart of the longitudinal force difference ΔFX and the corrected torque target value Tms when the corrected steering control is executed. As shown in this figure, the longitudinal force difference ΔFX increases from time t0 to time t3. For this reason, the maximum value MSm is updated every control cycle, and the corrected torque target value Tms increases. Subsequently, after time t3, the corrected torque target value Tms is constant unless the maximum value MSm is updated. Then, when a predetermined time τk has elapsed from the start of the μ split control at time t4, the corrected torque target value Tms is gradually brought close to zero. At this time, the time change amount (change gradient) of the corrected torque target value Tms is limited to a value corresponding to the time change amount (predetermined value Kdown) of the corrected maximum value MSml.

  As described above, according to the steering control device of the present embodiment, the maximum value MSm of the absolute value of the stabilization moment MS including the component of the longitudinal force difference ΔFX is stored during μ split control, and this maximum value is stored. A corrected steering target value (corrected torque target value) is obtained based on the value MSm. For this reason, when the μ split control is executed, even if the increase / decrease cycle of the longitudinal force FX ** of the left and right wheels is different and the longitudinal force difference ΔFX periodically increases / decreases, the corrected steering target value Tms varies accordingly. You can avoid it. Therefore, the influence on the steering wheel due to this can be suppressed, and the driver can be prevented from feeling uncomfortable.

  In this embodiment, the correction steering control is terminated when the μ split control continues for a predetermined time τk. As a result, it is possible to assist the counter steer operation corresponding to the sudden front-rear force difference-induced yaw moment that occurs immediately after the start of the μ split control, which is difficult for the driver to handle. In the present embodiment, the maximum value MSm is changed when the back-and-forth force operating member (brake pedal or accelerator pedal) is returned, but it is also possible not to change it. In such a case, when the μ split control continues for a predetermined time τk, the corrected steering control is terminated, so that it is possible to prevent the corrected steering control from being continued excessively until the return operation is performed.

  In this embodiment, when a return operation is performed, the maximum value MSm is corrected to obtain a corrected steering target value (corrected torque target value). For this reason, it is possible to assist the counter steer operation corresponding to the return operation, and to prevent the driver from feeling uncomfortable.

  Further, in the present embodiment, when the correction steering control is finished or when a return operation is performed, a limit is set on the amount of time change of the maximum value MSm. For this reason, the fluctuation | variation of the steering wheel 21 is relieve | moderated and it becomes possible to suppress the discomfort to a driver | operator. Moreover, it is possible to prevent excessive correction steering control from being continued after the return operation is performed.

(Second Embodiment)
A second embodiment of the present invention will be described. In the first embodiment, the case where one embodiment of the present invention is applied to a steering control apparatus that also performs a correction steering control that feeds back a vehicle motion state has been described. However, the feedback of the vehicle operating state is excluded from the correction steering control. Also good. In this case, the ECU 50 has a configuration in which the actual motion calculation means 50c, the target motion calculation means 50d, the comparison means 50e and the stabilization moment calculation means 50f shown in FIG. 2 are eliminated. Then, instead of the stabilization moment MS, the corrected steering target value is obtained using the longitudinal force difference ΔFX itself.

  Specifically, as indicated by the parentheses in FIG. 2, the longitudinal force difference ΔFX transmitted from the longitudinal force difference calculating means 50i to the stabilizing moment calculating means 50f is transmitted to the maximum value storing means 50j, and the maximum value is obtained. The storage means 50j stores the maximum value ΔFXm of the longitudinal force difference ΔFX, and the corrected steering target value calculation means 50k determines the corrected torque target value Tms based on the maximum value ΔFXm. Similarly, the maximum value correcting means 50q corrects the maximum value ΔFXm of the longitudinal force difference ΔFX stored in the maximum value storing means 50j, limits the time change amount of the corrected maximum value ΔFXms by the limiting means 50r, and finally The maximum value ΔFXml is calculated. Then, as shown in step 155 of FIG. 7, Tms = Fnc (ΔFXm), where Fnc (ΔFXm) is a map (see FIG. 4) or function with ΔFXm as an argument, and substitutes the maximum value ΔFXm. Thus, the corrected torque target value Tms can be calculated. When the duration tms of the μ split control has passed the predetermined time τk, the corrected torque target value Tms is obtained based on the maximum value ΔFXml in preference to the maximum value ΔFXm stored in the maximum value storage means 50j. Further, when the maximum value ΔFXm is decreased by the return operation determination, the maximum value ΔFXm is prioritized over the maximum value ΔFXml during the limiting process, and the corrected torque target value Tms is obtained using the maximum value ΔFXm.

  Thus, the corrected steering target value (corrected torque target value) is obtained using the longitudinal force difference ΔFX as it is. Since the cause of vehicle deflection during μ split control is the longitudinal force difference, the same effect as in the first embodiment can be obtained by obtaining the corrected steering target value based on the longitudinal force difference ΔFX. When the corrected steering target value is obtained using the longitudinal force difference ΔFX in this way, as shown in the parentheses in each figure, the stabilization moment MS shown in FIGS. 3 to 7 and its maximum value MSm are shown. May be replaced with the longitudinal force difference ΔFX or its maximum value ΔFXm. As the parameter is changed, as shown in step 135 of FIG. 7, for example, the coefficient K1 is changed to a coefficient K2 (a positive value smaller than 1 as in K1).

(Third embodiment)
A third embodiment of the present invention will be described. In the first and second embodiments, the case where the steering control mechanism 20 is configured by the EPS 24 and the steering control is performed by the steering torque control has been described. However, in the present embodiment, the steering gear ratio variable mechanism (VGRS) is used. A case where the steering control is performed by the steering angle control will be described.

  FIG. 10 is a schematic diagram illustrating the overall configuration of the motion control mechanism 10 of the vehicle 1 provided with the steering control device according to the present embodiment. In addition, since it is the same as that of 1st Embodiment regarding the structure other than VGRS27 among the motion control mechanisms 10 of this embodiment, only VGRS is demonstrated.

  The VGRS 27 includes a gear mechanism 27a and a motor 27b. The VGRS 27 controls the (absolute) rotation angle of the motor 27b to rotate the lower shaft 22b relative to the upper shaft 22a, and the steering angles of the left and right front wheels FL and FR that become steering wheels with respect to the rotation angle of the steering wheel 21 Adjust the ratio (steering gear ratio).

  For example, the VGRS 27 includes a known planetary gear mechanism including a sun gear 27aa connected to the upper shaft 22a, a ring gear 27ab connected to the motor 27b, and a carrier 27ac connected to the lower shaft 22b.

  Further, the steering control mechanism 20 of the present embodiment is provided with a steering angle sensor 28, and the steering angle of the steering wheel 21 by the driver is obtained.

  By controlling the rotation angle of the motor 27b of the VGRS 27, the steering control, that is, the vehicle speed sensitive steering gear ratio control, and the corrected steering control based on the front-rear force difference ΔFX between the left wheel FL, RL and the right wheel FR, RR. Can be executed. The vehicle speed-sensitive steering gear ratio control means that the steering stability is maintained by setting the steering gear ratio large during high-speed driving, and the steering gear ratio is set small during low-speed driving. Is to improve.

  Specifically, when the stabilization moment MS is used as in the first embodiment, the following modifications are made to the first embodiment. In addition, about the signal processing of steering angle control, etc., it shows using square brackets in each figure.

  In the third embodiment, the reference target value determining means 50a obtains a reference target value for adjusting the steering of the steering wheels FL and FR based on the operation of the steering operation member (steering wheel 21) by the driver. is there. In the first embodiment, the reference torque target value Ts is calculated as the reference target value in the reference target value determining means 50a shown in FIG. 2, but instead of this, based on the detection signal of the steering angle sensor 28, the steering wheel 21 of the steering wheel 21 is calculated. After obtaining the steering angle, a reference rudder angle target value δf is obtained based on a map or a relational expression showing the relationship between the steering angle, the vehicle body speed, and the steering gear ratio. This reference rudder angle target value δf is a target value of the rotation angle of the motor 27b for performing vehicle speed sensitive steering gear ratio control.

  Similarly, in the first embodiment, the corrected steering target value Tms is calculated by the corrected steering target value calculation means 50k. Instead, the corrected steering angle target value δms is calculated. Specifically, when the corrected rudder angle target value δms is obtained based on the maximum value MSm of the stabilization moment MS as in the first embodiment, the positive / negative sign stored in step 125 in step 155 of FIG. The maximum value MSm (or the maximum value MSms, MSm1) marked with is converted to the steering angle instead of torque conversion. That is, δms = NSnc (MSm), where NSnc (MSm) is a map or a function expression using MSm as an argument, and the corrected steering angle target value δms can be calculated by substituting the maximum value MSm. .

  Then, in the drive means 50b, the rotation angle target value (output target value) of the motor 27b corresponding to the final steering angle target value is obtained by adding the reference steering angle target value δf and the corrected steering angle target value δms. After being obtained, a motor control signal indicating a control instruction value for realizing it is output to the motor 27b. Accordingly, it is possible to execute the correction steering control for reducing the yaw moment due to the longitudinal force difference generated during the μ split control, and to reduce the counter steering operation of the driver during the μ split control.

  As described above, even when the steering control mechanism 20 is configured by the VGRS 27 and the steering control is performed by the steering angle control, the same effect as in the first embodiment can be obtained.

  When the VGRS 27 is employed as in this embodiment, when the vehicle motion state feedback is excluded from the corrected steering control as in the second embodiment, the corrected steering target value calculation unit 50k uses the maximum value ΔFXm. (Or the corrected steering angle target value δms can be obtained based on the maximum values ΔFXms, ΔFXml). In the same manner as described above, as shown in step 155 of FIG. 7, δms = Gnc (ΔFXm), where Gnc (ΔFXm) is a map (see FIG. 4) or function using ΔFXm as an argument. Yes, it is possible to obtain the corrected steering angle target value δms by substituting the maximum value ΔFXm.

(Fourth embodiment)
A fourth embodiment of the present invention will be described. In the present embodiment, the process executed by the ECU 50 is changed with respect to the first to third embodiments, and the other parts are the same, so only the different parts will be described.

  The longitudinal force difference ΔFX may decrease with a change in the road surface friction coefficient. FIG. 11 is a timing chart showing the state of the stabilization moment MS and the longitudinal force difference ΔFX when the road surface friction coefficient is changed. As shown in this figure, the road surface even if the driver's return operation is not performed. The actual values of the stabilization moment MS and the longitudinal force difference ΔFX are reduced with respect to the maximum values MSm and ΔFXm stored with the change of the friction coefficient. If this occurs before the predetermined time τ has elapsed from the start of the μ split control, the maximum value MSm will not be updated even if the actual value of the stabilization moment MS or the longitudinal force difference ΔFX decreases. For this reason, in the present embodiment, the maximum values MSm and ΔFXm are corrected when a period in which the difference between the maximum values MSm and ΔFXm and the actual value is equal to or greater than the predetermined value Km continues for a predetermined time τm or longer. .

  FIG. 12 is a diagram showing a block configuration of a part related to steering control described in the present embodiment in the ECU 50 of the present embodiment.

  As shown in this figure, the difference (| MSm | − | MS | (or | ΔFXm | − |) between the absolute value of the stabilization moment MS (or longitudinal force difference ΔFX) and the maximum value MSm (or maximum value ΔFXm). Comparison means 50t for determining whether or not ΔFX |) is equal to or greater than a predetermined value Km, and time counting means for counting the duration of the determination result that the difference output from comparison means 50t is equal to or greater than the predetermined value Km. 50u, and when the duration tc exceeds the predetermined time τm by the time counting means 50u, the fact is notified to the maximum value correcting means 50q, and the maximum value MSm (or maximum value ΔFXm) is corrected. It has become. For example, in the maximum value correcting means 50q, a positive coefficient smaller than 1 is added to the maximum value MSm (or the maximum value ΔFXm) when the duration tc is equal to or longer than the predetermined time τm, as in the case where the return operation is performed. A correction is made to reduce to a predetermined ratio by multiplying by K3.

  As described above, when the period in which the difference between the maximum value MSm (or ΔFXm) and the actual value is equal to or greater than the predetermined value Km continues for the predetermined time τm or longer, the maximum value MSm (or ΔFXm) is corrected. Even if the longitudinal force difference ΔFX decreases as the road surface friction coefficient changes, the corresponding maximum value MSm (or ΔFXm) can be corrected. In this case as well, if the restriction means 50r places a restriction on the time change amount of the maximum value MSms (or ΔFXms), it is possible to further suppress the driver from feeling uncomfortable.

(Fifth embodiment)
A fifth embodiment of the present invention will be described. In the present embodiment, the process executed by the ECU 50 is changed with respect to the first to fourth embodiments, and the other parts are the same, so only the different parts will be described.

  In the first to fourth embodiments, the corrected steering target values Tms and δms are calculated by storing the absolute value maximum value MSm of the stabilization moment MS or the absolute value maximum value ΔFXm of the longitudinal force difference ΔFX. It was. On the other hand, in the present embodiment, the corrected steering target values Tms and δms are calculated in advance based on the stabilization moment MS or the longitudinal force difference ΔFX, and the absolute maximum values Tmsm and δmsm are stored. Final corrected steering correction values Tmsa and δmsa are obtained.

  FIG. 13 is a diagram showing a block configuration of a part related to steering control described in the present embodiment in the ECU 50 of the present embodiment.

  As shown in this figure, in the present embodiment, a corrected steering target value calculating means 50k is disposed in front of the maximum value storing means 50j, and a corrected steering correction value calculating means 50s is newly added.

  In such a configuration, the corrected steering target values Tms and δms are calculated in advance by the corrected steering target value calculation means 50k based on the stabilization moment MS or the longitudinal force difference ΔFX. The relationship between the corrected steering target values Tms and δms with respect to the stabilization moment MS or the longitudinal force difference ΔFX is the same as in FIG. 4 described above. Then, the maximum values Tmsm and δmsm of the absolute values together with the positive and negative signs of the corrected steering target values Tms and δms are stored in the maximum value storage means 50j, and the values assigned to the maximum values Tmsm and δmsm are corrected steering. The correction value calculation means 50s sets the corrected steering correction values Tmsa and δmsa as final corrected steering target values.

  Further, the maximum value correcting means 50q corrects the maximum values Tmsm and δmsm stored in the maximum value storing means 50j based on the duration tms and the determination result DSm of the return operation by the same method as in the first embodiment. The maximum values Tmsms and δmsms are calculated. That is, if the duration tms exceeds the predetermined time τk, the maximum values Tmsm and δmsm are reduced to zero, and if the return operation is performed, the maximum values Tmsm and δmsm are reduced to a predetermined ratio before the return operation. Then, the limiting means 50r limits the amount of time change of the maximum values Tmsms and δmsms, and calculates the final maximum values Tmsml and δmsml. When the final maximum values Tmsml and δmsml are transmitted to the corrected steering correction value calculation means 50s, the correction steering correction value calculation means 50s determines that the maximum value storage means 50j when the duration time tms exceeds the predetermined time τk. The final maximum values Tmsml and δmsml are set as the corrected steering correction values Tmsa and δmsa in preference to the maximum values Tmsm and δmsm stored in. When the return operation is determined, the maximum values Tmsm and δmsm are prioritized, and these are set as the corrected steering correction values Tmsa and δmsa.

  As described above, the maximum corrected values Tmsm and δmsm of the corrected steering target values Tms and δms are stored, and the final corrected steering correction values Tmsa and δmsa may be obtained based on the stored values, as in the first to fourth embodiments. Similar effects can be obtained.

(Other embodiments)
In each of the above-described embodiments, the brake control mechanism 30 has been described that applies braking torque to the wheels FL to RR based on a hydraulic brake using the brake hydraulic pressure control actuator 31, but an electric motor such as an electric brake is used. The brake torque may be applied to the wheels FL to RR by generating the W / C pressure by pressing the brake pad directly against the disk rotor. In this case, for example, the braking torque can be obtained based on the control instruction value of the electric motor.

  In each of the above embodiments, when the return operation is performed, the maximum value MSm is reduced to a predetermined ratio with respect to that before the return operation. However, the maximum value MSm is not set to a predetermined ratio and corresponds to the operation amount of the return operation. The maximum value MSm may be reduced.

  Further, in each of the above embodiments, as the longitudinal force difference ΔFX, a value obtained by subtracting the sum of the longitudinal forces FXFL, FXRL of the left longitudinal wheel FL, RL from the sum of the longitudinal forces FXFR, FXRR of the right longitudinal wheel FR, RR is used. However, when the longitudinal force difference is a braking force difference, the longitudinal force difference ΔFX between the left and right wheels is set as the longitudinal force (braking force) FXfr of the right front wheel FR to the longitudinal force (braking force) of the left front wheel FL. ) A value obtained by subtracting FXfl may be used. When the longitudinal force difference is a driving force difference, a value obtained by subtracting the longitudinal force (driving force) of the left driving wheel from the longitudinal force (driving force) of the right driving wheel may be used.

  In the first to fourth embodiments, the restriction unit 50r performs restriction processing for restricting the amount of time change of the maximum values MSms and ΔFXms. However, the time of the corrected steering target values Tms and δms is used. Limiting processing for limiting the amount of change may be performed. Similarly, in the fifth embodiment, the limiting process is performed to limit the time variation of the maximum values Tmsms and δmsms in the limiting means 50r, but the time variation of the corrected steering correction values Tmsa and δmsa. Restriction processing may be performed to limit the number of items.

  The steps shown in each figure correspond to means for executing various processes.

1 is a schematic diagram showing an overall configuration of a vehicle motion control mechanism provided with a steering control device according to a first embodiment of the present invention. It is the figure which showed the block configuration of the part which relates to steering control among ECU. It is the timing chart which showed the change of the maximum value MSm memorize | stored with respect to the change of the stabilization moment MS. 6 is a map showing a relationship between a maximum value MSm and a corrected torque target value Tms. 6 is a timing chart showing how a maximum value MSm changes when a predetermined time τk has elapsed after the start of μ-split control. It is the timing chart which showed the mode of change of maximum value MSm when return operation was done. It is a flowchart of correction steering control. It is the map which showed the relationship between initial speed Vxi and predetermined time (tau) k. 6 is a timing chart of a longitudinal force difference ΔFX and a corrected torque target value Tms when the corrected steering control is executed. It is the schematic which showed the whole structure of the motion control mechanism of the vehicle provided with the steering control apparatus concerning 3rd Embodiment of this invention. It is the timing chart which showed the mode of stabilization moment MS and the longitudinal force difference (DELTA) FX when a road surface friction coefficient changes. It is the figure which showed the block configuration of the part which relates to steering control among ECU. It is the figure which showed the block configuration of the part which relates to steering control among ECU.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Vehicle, 10 ... Motion control mechanism, 20 ... Steering control mechanism, 21 ... Steering wheel, 22 ... Steering shaft, 22a ... Upper shaft, 22b ... Lower shaft, 23 ... Steering torque sensor, 24 ... EPS, 25 ... Steering gear Mechanism: 26 ... Steering link mechanism, 27 ... VGRS, 28 ... Steering angle sensor, 30 ... Brake control mechanism, 31 ... Brake hydraulic pressure control actuator, 32 ... W / C, 41 ... Wheel speed sensor, 42 ... W / C Pressure sensor, 43 ... Yaw rate sensor, 44 ... Longitudinal acceleration sensor, 45 ... Lateral acceleration sensor, 46 ... Pedal operation amount sensor, 50 ... ECU, 60 ... Brake pedal.

Claims (12)

In order to suppress the slip of the vehicle wheels, wherein while executing the slip suppression control for adjusting the longitudinal force of the vehicle wheel, the friction coefficient is different μ split road surface of the road surface passing through the left wheel wheel and the right wheel wheel during traveling the vehicular steering control apparatus of the vehicles that μ split control for executing slip suppression control is executed,
A first arithmetic means to calculating the longitudinal force of the vehicle wheels,
A second arithmetic means to calculating the longitudinal force difference between the right and left wheels on the basis of the longitudinal force,
A storage means to store a maximum value of the state quantity including the longitudinal force difference,
And third arithmetic means to calculating the corrected steering target value based on the maximum value,
The correction driving means to output a control instruction value based on the steering target value, the vehicle steering control apparatus characterized by comprising a. A fourth arithmetic means to the arithmetic between Continuation from the start of the μ split control,
If during the time the continuation is predetermined on a predetermined time Ma以, and a modification means to calculating the maximum value modified to reduce the maximum value stored in the memory manually stage to zero,
The third arithmetic hand stage, the vehicle steering control apparatus according to claim 1, characterized by calculating the modified steering target value based on said maximum value after correction by the correction manual stage. A determining hands stage that said detecting an operation state of the longitudinal force operating member for operating the front-rear force the driver's back operation is performed,
When the return operation has been performed, and a modification means to calculating the maximum value modified to reduce the maximum value stored in the storage hands stage,
The third arithmetic hand stage, the vehicle steering control apparatus according to claim 1 or 2, characterized in that for calculating said correction steering target value based on said maximum value after correction by the correction manual stage. The modified hand stage, when the return operation the longitudinal force operating member is returned to a position before the operation is complete, be modified to reduce the maximum value stored in the memory manually stages to zero The vehicle steering control device according to claim 3. A comparing hand stepped difference between the state quantity including the longitudinal force difference between the maximum value stored in the storage hands stage comparing determines whether more than a predetermined value,
A counting means to count the duration of when said difference is determined to exceed the predetermined value,
When said counted duration becomes the predetermined time Ma以, and a modification means to calculating the maximum value modified to reduce the maximum value stored in the storage hands stage,
The third arithmetic hand stage, a vehicle according to any one of claims 1 to 4, characterized in that for calculating said correction steering target value based on said maximum value after correction by the correction manual stage Steering control device. The vehicle steering control apparatus according to any one of claims 2 to 4, further comprising a restriction means to set the time change amount of restriction of the maximum value after manual repairs to the modified hand stage . In order to suppress the slip of the vehicle wheels, wherein while executing the slip suppression control for adjusting the longitudinal force of the vehicle wheel, the friction coefficient is different μ split road surface of the road surface passing through the left wheel wheel and the right wheel wheel during traveling the vehicular steering control apparatus of the vehicles that μ split control for executing slip suppression control is executed,
A first arithmetic means to calculating the longitudinal force of the vehicle wheels,
A second arithmetic means to calculating the longitudinal force difference between the right and left wheels on the basis of the longitudinal force,
And third arithmetic means to calculating the corrected steering target value based on the state quantity including the longitudinal force difference,
A storage means to store a maximum value of the correction steering target value,
A fourth arithmetic means to calculating the final correction steering target value based on the maximum value,
The final fixes and drive means to output a control instruction value based on the steering target value, the vehicle steering control apparatus characterized by comprising a. A fifth arithmetic means to the arithmetic between Continuation from the start of the μ split control,
If during the time the continuation is predetermined on a predetermined time Ma以, and a modification means to calculating the maximum value modified to reduce the maximum value stored in the memory manually stage to zero,
It said fourth arithmetic hand stage, the vehicle steering control apparatus according to claim 7, characterized in that for calculating the final correction steering target value based on said maximum value after correction by the correction manual stage. A determining hands stage that said detecting an operation state of the longitudinal force operating member for operating the front-rear force the driver's back operation is performed,
When the return operation has been performed, and a modification means to calculating the maximum value modified to reduce the maximum value stored in the storage hands stage,
Said fourth arithmetic hand stage, the vehicle steering control according to claim 7 or 8, characterized in that computing the final correction steering target value based on said maximum value after correction by the correction manual stage apparatus. The modified hand stage, when the return operation the longitudinal force operating member is returned to a position before the operation is complete, be modified to reduce the maximum value stored in the memory manually stages to zero The vehicle steering control device according to claim 9. A comparing hand stepped difference between the corrected steering target value and said stored maximum value in said storage hands stage comparing determines whether more than a predetermined value,
A counting means to count the duration of when said difference is determined to exceed the predetermined value,
When said counted duration becomes the predetermined time Ma以, and a, a modification means to calculating the maximum value modified to reduce the maximum value stored in the storage hands stage The vehicle steering control device according to claim 7, wherein the vehicle steering control device is a vehicle steering control device. The vehicle steering control apparatus according to any one of claims 8 to 11, further comprising a restriction means to set the time change amount of restriction of the maximum value after manual repairs to the modified hand stage .

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