JP2008080840A - Four-wheel active steering system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a four-wheel active steering system free of imposing a steering burden on a driver even if the responsiveness on one side has changed. <P>SOLUTION: The four-wheel active steering system is equipped with: a front-wheel active steering means to give an auxiliary steering angle to the front wheels; a rear-wheel active steering means to give an auxiliary steering angle to the rear wheels; and a four-wheel active steering controlling means to give commands about the auxiliary steering angles to both active steering means so that a desired vehicle behavior characteristic is obtained, wherein presumption is made for the responsiveness of at least either of a steering condition sensing means to sense the steering condition of the driver and the front-wheel and rear-wheel active steering means. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle control system, and more particularly to a vehicle equipped with active steering that obtains desired vehicle behavior characteristics.

Conventionally, various technologies related to a four-wheel active steering system having a control law for obtaining desired vehicle behavior characteristics by controlling the steering angles of the front and rear wheels have been proposed (see, for example, Patent Document 1). In this publication, when an abnormality is detected in the active steering means on the front wheel side and the rear wheel side, the response of the active steering means is reduced.
JP 2003-182622 A

  If the responsiveness of the active steering means is reduced as in the above prior art, the amount of steering required by the driver is different from that during normal control, so the driver's corrective action is difficult and the vehicle behavior is less likely to converge. There was a problem that the burden on the driver was heavy.

  The present invention has been made paying attention to the above-mentioned problem, and its object is to place a steering burden on the driver even if the responsiveness of either the front wheel or the rear wheel active steering means changes. It is an object to provide a four-wheel active steering system that does not have any.

  In order to achieve the above object, in the four-wheel active steering system of the present invention, a front wheel side active steering means for giving an auxiliary steering angle to a front wheel, a rear wheel side active steering means for giving an auxiliary steering angle to a rear wheel, and a desired Steering state detection for detecting the steering state of a driver in a four-wheel active steering system comprising: a four-wheel active steering control means for commanding an auxiliary steering angle to both the active steering means so as to obtain a vehicle behavior characteristic of Responsiveness estimating means for estimating the responsiveness of at least one of the front wheel side and the rear wheel side active steering means, the detected steering state and the change in the estimated one responsiveness, Responsiveness changing means for changing the other responsiveness is provided.

  Estimate the responsiveness of at least one of the active steer means, and when the responsiveness of one of them decreases, increase the responsiveness of the other to suppress the change in vehicle behavior or compensate for the lack of change in the vehicle behavior convergence This improves the driver's steering burden. Further, by estimating the responsiveness, it is possible to cope with the system before the deviation from the target behavior occurs, further suppressing the vehicle behavior and improving the convergence.

  Hereinafter, the best mode for realizing a vehicle control system of the present invention will be described based on an embodiment shown in the drawings.

[Configuration of vehicle control system]
FIG. 1 is a system configuration diagram illustrating a vehicle control system according to the first embodiment. The vehicle according to the first embodiment controls an engine controller (hereinafter referred to as ECU) 1 that controls an engine, an automatic transmission controller (hereinafter referred to as ATCU) 2 that controls an automatic transmission, and various meters. Meter controller (hereinafter referred to as MCU) 3, steering angle sensor 7 for detecting the steering angle of the driver, and integrated sensor 8 for detecting state quantities (yaw rate, lateral acceleration, longitudinal acceleration, etc.) related to the behavior of the vehicle. Is installed.

  The steering angle sensor 7 is provided with a controller 7a that outputs an electrical signal detected according to a change in angle as an angle signal, and a value obtained by removing a noise component or the like is output every predetermined period (for example, every 10 msec). . Further, the integrated sensor 8 is provided with a controller 8a for outputting an electric signal detected according to a change in the behavior of the vehicle as a yaw rate signal, a lateral acceleration signal, and a longitudinal acceleration signal, and a value obtained by removing noise components and the like. It is output every predetermined period (for example, every 5 msec).

  In addition, a front wheel steering unit 40 capable of adding / subtracting the steering angle of the front wheels 4a with respect to the steering angle of the driver, a rear wheel steering unit 50 capable of controlling the steering angle of the rear wheels 5a, and the wheels 4a, 5a. A brake unit 60 that can independently control the braking force according to the traveling state is mounted.

  The front wheel steering unit 40 includes a front wheel controller 4 and a front wheel actuator 41 that operates based on a command from the front wheel controller 4, and is disposed below an instrument panel in front of the vehicle. The rear wheel steering unit 50 includes a rear wheel controller 5 and a rear wheel actuator 51 that operates based on a command from the rear wheel controller 5, and is disposed in the vicinity of the rear wheel behind the vehicle. The brake unit 60 includes a brake controller 6 and a brake actuator 61 that operates based on a command from the brake controller 6, and is disposed in the engine room.

  The ECU 1, the ATCU 2, the MCU 3, the steering angle sensor 7, the brake controller 6, and the rear wheel controller 5 are provided with a low speed communication control port and are connected by a low speed CAN communication line 100. The communication speed of the low-speed CAN communication line 100 is configured so that data output from each controller can be transmitted and received every 10 msec.

  In CAN communication, a combination of a high signal and a low signal is output to two communication lines, and a bit signal is transmitted / received based on a deviation between these signals. Therefore, even if a signal is disturbed due to a disturbance or the like, a disturbance occurs simultaneously on the two communication lines. Therefore, a stable bit signal can be transmitted and received by taking a deviation. Further, in this communication line, sensor signals and the like output from each controller are output at a constant cycle or every time an event occurs, and only a necessary controller receives necessary information.

  The front wheel controller 4, the rear wheel controller 5, the brake controller 6, and the integrated sensor 8 are provided with a high-speed communication control port and are connected by a high-speed CAN communication line 200. The communication speed of the high-speed CAN communication line 200 is configured so that data output from each controller can be transmitted and received every 1 msec. In communication via the low-speed CAN communication line 100, the amount of data that can be transmitted / received within a unit time is small, and in communication via the high-speed CAN communication line 200, the amount of data that can be transmitted / received within a unit time is large. .

  As described above, the brake controller 6 and the rear wheel controller 5 are provided with both a high-speed communication control port and a low-speed communication control port, and are connected to both the high-speed CAN communication line 200 and the low-speed CAN communication line 100. Yes.

[4-wheel active steering system]
FIG. 2 is a system diagram showing a configuration of a four-wheel active steering system. The theory that the vehicle of the first embodiment is optimal to achieve such yaw rate and lateral acceleration as steering feeling and vehicle behavior characteristics when a driver generates a certain steering angle at a certain vehicle speed. Based on this, a four-wheel active steering system is provided in which auxiliary steering angles are given to the front and rear wheels. In other words, the feedback control system using a yaw rate sensor, a lateral acceleration sensor, or the like does not reflect the driver's steering intention, but starts control based on the actually generated vehicle behavior. It is not possible to obtain the optimal vehicle behavior characteristics according to the steering intention. Therefore, before and after the vehicle behavior is generated by feedforward control with respect to the steering angle and the vehicle speed, the front and rear wheel auxiliary steering angles are set to ensure a quick response. Details of the control configuration will be described later.

(Configuration of front wheel steering unit)
The front wheel actuator 41 is provided on a steering shaft between the steering wheel and the rack and pinion mechanism. The steering shaft is composed of a first steering shaft connected to the steering wheel and a second steering shaft connected to the pinion, and the rotation of the second steering shaft with respect to the rotation angle of the first steering shaft is driven by the front wheel side motor 42. The angle is controlled so that it can be added or subtracted. The front wheel actuator is a well-known technique and will not be described.

  The front wheel side motor 42 is provided with a front wheel side rotation angle sensor 43 that detects the rotation angle of the front wheel side motor 42 and is output to the front wheel controller 4. In the front wheel controller 4, a calculation unit 401 that calculates a driving amount of the front wheel side motor 42 with respect to a target rudder angle calculated in a target value calculation unit 504 (described later) (a driving amount corresponding to the given auxiliary steering angle); A servo control unit 402 that feedback-controls a control amount of the side motor 42 based on a detection value of the front wheel side rotation angle sensor 43 and a front wheel side driver unit 403 that outputs a current value to the front wheel side motor 42 are provided. Yes.

  The current is supplied to the front wheel side motor 42 by calculating a current command value corresponding to the deviation between the motor rotation angle corresponding to the target front wheel steering angle (auxiliary steering angle) and the actual motor rotation angle. The output voltage is supplied by duty control so as to be a value. Therefore, the output voltage Duty is determined based on the current command value, and a current value corresponding to the output voltage Duty is output. However, since the motor rotation speed with respect to the current value varies depending on the load applied to the front wheel side motor 42, the back electromotive force also varies. Therefore, in this case, when a larger current command value is output, the output voltage Duty also increases and a larger current value flows.

  Further, the front wheel controller 4 is provided with a front wheel side current sensor 403a for detecting an actual current value supplied to the front wheel side motor 42. The front wheel controller 4 transmits a current command value, an output voltage Duty, and an actual current value detected by the front wheel side current sensor 403a as control information to the rear wheel controller 5 (particularly, the target value calculation unit 504). .

(Configuration of rear wheel steering unit)
The rear wheel actuator 51 is provided between the left and right rear wheels 5a. The left and right rear wheels 5a are connected by a parallel link. When one side of this link is moved in the vehicle width direction by the rear wheel side motor 51, a steering angle is generated in the rear wheel 5a due to elastic deformation of the parallel link. Since this rear wheel actuator is a well-known technique, description thereof is omitted.

  The rear wheel side motor 52 is provided with a rear wheel side rotation angle sensor 53 that detects the rotation angle of the rear wheel side motor 52 and is output to the rear wheel controller 5. In the rear wheel controller 5, there is a calculation unit 501 that calculates a drive amount of the rear wheel side motor 52 with respect to a target steering angle calculated by a target value calculation unit 504 (described later) (a drive amount corresponding to the provided auxiliary steering angle). A servo control unit 502 that feedback-controls a control amount of the rear wheel side motor 52 based on a detection value of the rear wheel side rotation angle sensor 53, and a rear wheel side driver unit that outputs a current value to the rear wheel side motor 52. 503 and a target value calculation unit 504 for calculating the target rudder angle of the front and rear wheels based on the steering angle detected by the steering angle sensor 7 and the vehicle speed.

  Note that the supply of current to the rear wheel side motor 52 is the same as the supply of current to the front wheel side motor 42, and thus the description thereof is omitted. Further, the rear wheel controller 5 is provided with a rear wheel side current sensor 503 a that detects the actual current value supplied to the rear wheel side motor 52, similarly to the front wheel controller 4. The rear wheel controller 5 transmits a current command value, an output voltage Duty, and an actual current value detected by the rear wheel side current sensor 503a as control information to the target value calculation unit 504.

  The front wheel controller 4 controls the front wheel side motor 42 based on the target steering angle of the front wheels calculated by the target value calculation unit 504. The target value calculation unit 504 is not limited to the rear wheel controller 5 but may be provided in the front wheel controller 4 or in both, and is not particularly limited.

(4-wheel active steering control configuration)
The rear wheel controller 5 connected to the low-speed CAN communication line 100 receives the steering angle information from the steering angle sensor 7 connected to the low-speed CAN communication line 100 and the vehicle speed information from the ATCU 2 connected to the low-speed CAN communication line 100. The target value calculation unit 504 calculates a target front wheel steering angle and a target rear wheel steering angle based on these two values.

  FIG. 3 is a block diagram illustrating a control configuration of the target value calculation unit 504. The target value calculation unit 504 includes a target value generation unit 5041 that generates a target yaw rate and a target lateral acceleration based on the steering angle information and the vehicle speed, and a front wheel target rudder angle and a rear wheel target rudder based on the target yaw rate and the target lateral acceleration. Based on the target output generation unit 5042 for calculating the angle and various control information (current command value, actual current value, output voltage Duty in the front wheel and rear wheel controllers 4, 5) input to the rear wheel controller 5, the front wheel actuator 41 and the rear wheel actuator 51 are provided with a responsiveness estimating unit 5043 and an output correcting unit 5044 for correcting the front and rear wheel target rudder angles based on the steering angle, the vehicle speed, and the estimated responsiveness. The corrected front and rear wheel target rudder angles corrected by the output correction unit 5044 are output to the control blocks 401, 402, 403, 501, 502, and 503 described above.

(Configuration of response estimation unit)
Here, the responsiveness estimating unit 5043 will be supplementarily described. The responsiveness estimation unit 5043 includes three responsiveness estimation methods. Hereinafter, each response estimation method will be described.

[Response estimation based on actuator load]
FIG. 6 is a responsiveness determination map in which the rotation speed of the front wheel side motor 42 is the vertical axis and the front wheel side output voltage Duty is the horizontal axis. The hatched area in FIG. 6 is set as the responsiveness reduction area. If the motor speed does not increase despite the large output voltage Duty, it can be determined that the load on the front wheel actuator 41 is large. That is, even if the current command value for the deviation between the target front wheel rudder angle and the actual rudder angle is output, a torque sufficient to overcome the load cannot be obtained and the responsiveness decreases. Therefore, in the first embodiment, the responsiveness is estimated based on the relationship between the output voltage Duty and the motor rotation speed.

  As another determination of responsiveness, for example, it may be considered to determine that the responsiveness is lowered based on a state in which the deviation between the target front wheel steering angle and the actual steering angle does not shrink. However, it can only be determined based on feedback information of the actual steering angle, and a quick determination cannot be achieved. On the other hand, in the first embodiment, quick determination can be made by estimating the responsiveness based on information having a control phase that is earlier than the actual deviation of the target front wheel steering angle and the actual steering angle. . Since the same estimation is made for the rear wheel motor 52, the description thereof is omitted.

[Response estimation based on overcurrent]
FIG. 7 is a responsiveness determination map in which the actual current value flowing to the front wheel side motor 42 is the vertical axis and the current command value to the front wheel side motor 42 is the horizontal axis. The hatched area in FIG. 7 is set as the responsiveness increasing area. The current command value is compared with the actual current value, and when the actual current value is larger than the current command value by a predetermined value P, it can be determined that an overcurrent is flowing. Since the overcurrent flows means that the steering load is large, the responsiveness decreases.

  Therefore, it can be estimated that the responsiveness is lowered based on the current command value and the actual current value. This method is also a responsiveness estimation method based on information with an early control phase, similar to the responsiveness estimation based on the actuator load. Since the same estimation is made for the rear wheel motor 52, the description thereof is omitted.

[Response estimation based on temperature rise]
FIG. 8 is a responsiveness determination map in which the temperature of the front wheel side motor 42 (or a board such as a driver) is the vertical axis and the current command value integrated value to the front wheel side motor 42 is the horizontal axis. A region where the current command value integrated value in FIG. 8 is equal to or greater than the predetermined value t1 is set as a responsiveness reduction region. The temperature of the motor, the substrate, etc. can be roughly estimated from the flowing current. When the temperature exceeds a predetermined value, it is determined that an abnormality has occurred in the four-wheel active steering system, and active steer control is performed to reduce the responsiveness and execute control to suppress the temperature rise. .

  Therefore, the responsiveness estimation unit 5043 can estimate the decrease in responsiveness by grasping in advance that the four-wheel active steering control side performs the process of reducing the responsiveness using the current command value integrated value. it can. This method is also a responsiveness estimation method based on information with an early control phase, similar to the responsiveness estimation based on the actuator load. Since the same estimation is made for the rear wheel motor 52, the description thereof is omitted.

  If it is determined that the responsiveness may change in any of the three responsiveness estimation methods, the responsiveness estimation unit 5043 estimates a decrease in responsiveness.

  As for the increase in responsiveness, for example, when a command for giving an auxiliary rudder angle is output, a state in which the actual rudder angle overshoots the target rudder angle is detected, and an excessive overshoot occurs. If so, it may be configured to determine that the responsiveness has increased.

(Control configuration of output correction unit)
FIG. 4 is a block diagram illustrating a control configuration of the output correction unit 5044. The output correction unit 5044 includes a steering state determination unit 5044a that determines whether the driver's steering state is increased or decreased based on the steering information, and the front wheel control state is addition control or subtraction based on the front and rear wheel target rudder angles. Based on the vehicle speed, the steering state, the front and rear wheel target rudder angle, the front and rear wheel control state, and the estimated responsiveness, which determines whether the control or the rear wheel control state is in-phase control or reverse phase control. Thus, a responsiveness changing unit 5044c that performs correction processing when the responsiveness decreases and outputs the final corrected front and rear wheel target rudder angle is provided.

  In the first embodiment, the increase in the turn represents a state in which the steering angle increases based on the driver's intention to turn, that is, the time when the steering angular velocity is positive, and the switch back refers to the intention to end the turn of the driver. It is assumed that the steering angle decreases, that is, the steering angular velocity is negative. Therefore, when determining the steering state, the determination is made based on the steering angular velocity.

  Addition control refers to control for adding the auxiliary steering angle to the steering angle (control in which the yaw rate or the like increases compared to only the driver's steering), and subtraction control refers to the auxiliary steering angle with respect to the steering angle. (Control in which the yaw rate or the like decreases compared to the driver's steering only). Hereinafter, a state where the influence of the subtraction control is strong is referred to as “slow”, and a state where the influence of the addition control is strong is referred to as “quick”. For example, it is quicker when not controlled than when subtracted, and is slower when not controlled than when added.

  In-phase control refers to control that gives the rear wheel steering angle in the same direction as the driver's steering angle (control in which yaw rate or the like is reduced compared to the driver's steering only). This represents control for giving the rear wheel steering angle in a direction opposite to the steering angle of the driver (control in which the yaw rate or the like is increased compared to the driver's steering only).

It supplements about the specific scene where these each control is performed.
In a low vehicle speed range (such as a parking lot or a narrow alley), the front wheel actuator 41 performs addition control and the rear wheel actuator 51 performs reverse-phase control to reduce the amount of steering by the driver. To achieve the effective characteristics.

  In the middle vehicle speed range (winding road, etc.), the front wheel actuator 41 performs addition control and the rear wheel actuator 51 temporarily performs reverse phase control to achieve a quick response as a vehicle to the driver's steering intention. In order to ensure the subsequent stability while generating the yaw rate, it is switched to the in-phase control. Alternatively, the yaw rate may be generated quickly only by the front wheel actuator 41 without operating the rear wheel actuator 51.

  In a high vehicle speed region (lane change on a highway, etc.), the steering-yaw rate gain is high as a characteristic of the vehicle. Thus, the rear wheel actuator 51 performs in-phase control, thereby achieving a smooth lane change.

(Response change control processing)
FIG. 5 is a flowchart showing the responsiveness change control process in the responsiveness changing unit 5044c.

  In step S1, it is determined whether or not the responsiveness of the front wheel actuator 41 and the rear wheel actuator 51 estimated by the responsiveness estimation unit 5043 has changed (decrease or increase), and if so, the process proceeds to step S2. Otherwise, this control flow ends.

  In step S2, the determination result of the front and rear wheel control state determined by the front and rear wheel control state determination unit 5044b is read.

  In step S3, the steering state determined by the steering state determination unit 5044a is read. If it is increased, the process proceeds to step S4, and if it is switched back, the process proceeds to step S5.

  In step S4, a correction process for increasing steering is executed. Specifically, the target rudder angle is changed by multiplying the target rudder angle by a gain α in accordance with the combination of the steering state and the actuator whose responsiveness is reduced or increased. The correction process at the time of additional steering will be described later.

  In step S5, a correction process at the time of switching back steering is executed. Specifically, the target rudder angle is changed by multiplying the target rudder angle by a gain α in accordance with the combination of the steering state and the actuator whose responsiveness is reduced or increased. The correction process at the time of switching back steering will be described later.

(Correction processing during additional steering)
Next, the correction process at the time of additional steering will be described. In the response change control process of the first embodiment, the response is changed only when the front wheel actuator 41 performs subtraction control and the rear wheel actuator 51 performs in-phase control. As described above, a scene where such a combination control is performed is a lane change or the like in a high vehicle speed region. This is because in a region where the steering-yaw rate gain is high, the burden on the driver's steering is large, and therefore it can be said that there is a high demand for stabilization of the vehicle behavior particularly in this scene.

  FIG. 9A is a table showing the relationship between each responsiveness combination at the time of additional steering and the responsiveness changing process corresponding to the combination. When the steering is increased, the driver basically intends to turn, and it is necessary to generate the yaw rate and the lateral speed according to the driving condition (in this case, when the lane change starts at high speed). It is a scene.

  When the response of the front wheel actuator 41 decreases, the response of the rear wheel actuator 51 is increased. In the front wheel subtraction control and the rear wheel in-phase control, when the response of the front wheel subtraction control is reduced, a quick operation is performed, and a yaw rate and a lateral speed higher than desired are generated. Therefore, the cornering force of the rear wheel is increased by increasing the responsiveness of the rear wheel in-phase control. As a result, the effect of suppressing the yaw rate and the lateral speed is enhanced, and as a result, the behavior change accompanying the decrease in the responsiveness of the front wheel actuator 41 is absorbed and stabilized.

  When the response of the rear wheel actuator 51 is lowered, the response of the front wheel actuator 41 is increased. In the front wheel subtraction control and the rear wheel in-phase control, when the responsiveness of the rear wheel in-phase control is lowered, the cornering force of the rear wheel is lowered, and a yaw rate and a lateral speed higher than desired are generated. Therefore, the cornering force of the front wheels is lowered by increasing the responsiveness of the front wheel subtraction control. As a result, the effect of suppressing the yaw rate and the lateral speed is enhanced, and as a result, the behavior change accompanying the decrease in the responsiveness of the rear wheel actuator 51 is absorbed and stabilized.

  When the response of the front wheel actuator 41 is increased, the response of the rear wheel actuator 51 is decreased. In the front wheel subtraction control and the rear wheel in-phase control, if the response of the front wheel subtraction control is increased, the response becomes slow, and a desired yaw rate and lateral speed cannot be obtained. Therefore, the cornering force of the rear wheel is lowered by reducing the responsiveness of the rear wheel in-phase control. As a result, the effect of generating the yaw rate and the lateral speed is enhanced, and as a result, the shortage of behavior change accompanying the increase in the response of the front wheel actuator 41 is absorbed and stabilized.

  When the response of the rear wheel actuator 51 is increased, the response of the front wheel actuator 41 is decreased. In the front wheel subtraction control and the rear wheel in-phase control, if the responsiveness of the rear wheel in-phase control is increased, the cornering force of the rear wheel is increased, and a desired yaw rate and lateral speed cannot be obtained. Therefore, the cornering force of the front wheels is increased by reducing the responsiveness of the front wheel subtraction control. As a result, the effect of generating the yaw rate and the lateral speed is enhanced, and as a result, the insufficient behavior change accompanying the increase in the response of the rear wheel actuator 51 is absorbed and stabilized.

(Correction processing during switchback steering)
Next, the correction process at the time of switching back steering will be described. In the response change control process of the first embodiment, the response is changed only when the front wheel actuator 41 performs subtraction control and the rear wheel actuator 51 performs in-phase control.

  FIG. 9B is a table showing the relationship between each responsiveness combination at the time of switchback steering and the responsiveness changing process corresponding to the combination. In the case of switchback steering, the driver basically intends to end the turn, and the yaw rate or the lateral speed may decrease depending on the driving state (in this case, the lane change at the time of high speed driving, etc.). This is a necessary scene.

  When the response of the front wheel actuator 41 is lowered, the response of the rear wheel actuator 51 is lowered. In the front wheel subtraction control and the rear wheel in-phase control, if the response of the front wheel subtraction control is reduced, it becomes quick, and the yaw rate and the lateral speed are excessively reduced, resulting in overshoot. Therefore, the cornering force of the rear wheel is increased by reducing the responsiveness of the rear wheel in-phase control. As a result, the yaw rate suppression effect is enhanced, and as a result, the behavior convergence delay accompanying the decrease in the response of the front wheel actuator 41 is absorbed and stabilized.

  When the responsiveness of the rear wheel actuator 51 is lowered, the responsiveness of the front wheel actuator 41 is lowered. In the front wheel subtraction control and the rear wheel in-phase control, if the responsiveness of the rear wheel in-phase control decreases, the yaw rate and the lateral speed decrease are delayed. Therefore, quickness is achieved by reducing the responsiveness of the front wheel subtraction control, and the cornering force of the front wheels is lowered. As a result, the yaw rate suppression effect is enhanced, and as a result, the behavior convergence delay accompanying the responsiveness reduction of the rear wheel actuator 51 is absorbed and stabilized.

  When the response of the front wheel actuator 41 is increased, the response of the rear wheel actuator 51 is increased. In front wheel subtraction control and rear wheel in-phase control, if the responsiveness of the front wheel subtraction control increases, it becomes slow, and the yaw rate and lateral speed decrease are delayed. Therefore, the cornering force of the rear wheel is lowered by increasing the responsiveness of the rear wheel in-phase control. As a result, the yaw rate suppressing effect is enhanced, and as a result, the behavior change shortage accompanying the increase in the response of the front wheel actuator 41 is absorbed and stabilized.

  When the response of the rear wheel actuator 51 is increased, the response of the front wheel actuator 41 is increased. In the front wheel subtraction control and the rear wheel in-phase control, if the responsiveness of the rear wheel in-phase control is increased, the yaw rate and the lateral speed are excessively decreased, resulting in overshooting. Therefore, the cornering force of the front wheels is lowered by increasing the responsiveness of the front wheel subtraction control. As a result, the yaw rate suppressing effect is enhanced, and as a result, the behavior convergence delay accompanying the increase in the response of the rear wheel actuator 51 is absorbed and stabilized.

(How to change responsiveness)
Next, a specific method for changing responsiveness will be described. Basically, there are two types of system operation: increasing or decreasing the responsiveness. In order to increase the responsiveness, the deviation from the target value may be increased. On the other hand, in order to decrease the responsiveness, the deviation from the target value may be decreased.

Therefore, when one of the responsiveness changes, the value obtained by applying the tuning parameter α to the auxiliary steering angle δh given to the actuator whose responsiveness has changed is set to the auxiliary steering angle δs of the other actuator having the appropriate responsiveness. The other responsiveness is changed by adding (or subtracting) to. Here, if the target rudder angle after correction of the other actuator having an appropriate response is δ *,
δ * = δs + δh × α
It is expressed.

  FIG. 10 is a tuning parameter map for increasing responsiveness, and FIG. 11 is a tuning parameter map for decreasing responsiveness. Since the demand for stabilization of vehicle behavior is stronger in the higher vehicle speed region, the correction amount is set to be larger in the higher vehicle speed region.

  As described above, even if the control state of each actuator is the same, whether to increase or decrease the response differs depending on the difference in the steering state. Therefore, based on the steering state, the control state, the actuator whose response has changed, and the direction of change in response (increase or decrease), it is determined whether to increase or decrease the response of the other actuator having the appropriate response. To do. Then, α is determined from the map shown in FIG. 10 when increasing, and α is determined from the map shown in FIG. 11 when decreasing. Note that α may be appropriately changed so that the vehicle behavior can be finely adjusted.

For example, a case is assumed in which the response of the front wheel actuator 41 is lowered and the response of the rear wheel actuator 51 is changed during steering. As shown in FIG. 9A, in this case, since it is necessary to improve the response of the rear wheel actuator 51, α is determined from the map of FIG. Next, assuming that the auxiliary steering angle given to the front wheels is δf, the auxiliary steering angle given to the rear wheels is δr, and the corrected rear wheel target rudder angle after the response change is δr *,
δr * = δr + δf × α
It becomes.

  FIG. 12 is a simulation result showing the effect of the responsiveness change control process. This represents the yaw rate and lateral speed when a sine wave is input at a steering angle of ± 20 ° and 0.5 Hz when driving at a constant speed of 160 km / h. In FIG. 12, the dotted line represents the normal control time (front wheel side subtraction control, rear wheel side in-phase control) with appropriate responsiveness, the solid line represents the time when the response of the front wheel actuator 41 has decreased, and the dashed line represents the front wheel actuator. The time when the responsiveness change control processing of the first embodiment is performed when the responsiveness of 41 is lowered is shown. As shown in FIG. 12, when the responsiveness of the front wheel actuator 41 decreases, both the yaw rate and the lateral speed are excessively generated. On the other hand, it can be seen that the vehicle behavior characteristic close to that during normal control is obtained by performing the response change control process of the first embodiment.

As described above, in the first embodiment, the following effects can be obtained.
(1) In a four-wheel active steering system, a steering state determination unit 5044a that detects the steering state of the driver, a responsiveness estimation unit 5043 that estimates the responsiveness of at least one of the front wheel actuator 41 and the rear wheel actuator 51, and detection A responsiveness changing unit 5044c is provided that changes the responsiveness of the other in response to the estimated steering state and the estimated change in one responsiveness.

  The response of at least one of the actuators 41 and 51 is estimated, and when the response of one of the actuators decreases, the response of the other is increased, thereby suppressing the vehicle behavior and improving the convergence. The burden can be reduced. In addition, by estimating the responsiveness, it is possible to cope with the system before the deviation from the target behavior occurs, further suppressing the vehicle behavior and improving the convergence.

  (2) The responsiveness changing unit 5044c increases the responsiveness of the other when the detected steering state is further increased and the estimated responsiveness is reduced when the detected steering state is increased.

  The first embodiment is premised on front wheel subtraction control and rear wheel in-phase control. At this time, for example, when the response of the front wheel actuator 41 is lowered, the response of the rear wheel actuator 51 is increased. As a result, the effect of suppressing the yaw rate and the lateral speed can be enhanced, and as a result, the behavior change accompanying the decrease in the responsiveness of the front wheel actuator 41 can be absorbed and stabilized.

  Similarly, when the response of the rear wheel actuator 51 is lowered, the response of the front wheel actuator 41 is increased. As a result, the effect of suppressing the yaw rate and the lateral speed can be enhanced, and as a result, the behavior change accompanying the decrease in the responsiveness of the rear wheel actuator 51 can be absorbed and stabilized.

  (3) The responsiveness changing unit 5044c reduces the responsiveness of the other when the detected steering state is increased and the steering state is increased and the estimated one responsiveness is increased.

  The first embodiment is premised on front wheel subtraction control and rear wheel in-phase control. At this time, for example, when the response of the front wheel actuator 41 is increased, the response of the rear wheel actuator 51 is decreased. As a result, the effect of generating the yaw rate and the lateral speed can be enhanced, and as a result, the lack of behavior change accompanying the increase in the response of the front wheel actuator 41 can be absorbed and stabilized.

  Similarly, when the response of the rear wheel actuator 51 is increased, the response of the front wheel actuator 41 is decreased. As a result, the effect of generating the yaw rate and the lateral speed can be enhanced, and as a result, the insufficient behavior change associated with the increased response of the rear wheel actuator 51 can be absorbed and stabilized.

  (4) When the detected steering state is the switchback steering state and one of the estimated responsiveness decreases, the responsiveness changing unit 5044c decreases the other responsiveness.

  The first embodiment is premised on front wheel subtraction control and rear wheel in-phase control. At this time, for example, when the responsiveness of the front wheel actuator 41 is lowered, the responsiveness of the rear wheel actuator 51 is lowered. As a result, the effect of suppressing the yaw rate can be enhanced, and as a result, the behavior convergence delay accompanying the decrease in the response of the front wheel actuator 41 can be absorbed and stabilized.

  Similarly, when the responsiveness of the rear wheel actuator 51 is lowered, the responsiveness of the front wheel actuator 41 is lowered. As a result, the effect of suppressing the yaw rate can be enhanced, and as a result, the behavior convergence delay accompanying the responsiveness reduction of the rear wheel actuator 51 can be absorbed and stabilized.

  (5) When the detected steering state is the switchback steering state and the estimated one responsiveness increases, the responsiveness changing unit 5044c increases the other responsiveness.

  The first embodiment is premised on front wheel subtraction control and rear wheel in-phase control. At this time, for example, when the response of the front wheel actuator 41 is increased, the response of the rear wheel actuator 51 is increased. As a result, the effect of suppressing the yaw rate can be enhanced, and as a result, the lack of behavior change accompanying the increase in the response of the front wheel actuator 41 can be absorbed and stabilized.

  Similarly, when the response of the rear wheel actuator 51 is increased, the response of the front wheel actuator 41 is increased. Thereby, the effect of suppressing the yaw rate can be enhanced, and as a result, the behavior convergence delay accompanying the increase in the response of the rear wheel actuator 51 can be absorbed and stabilized.

  (6) The responsiveness changing unit 5044c is executed when the four-wheel active steering control gives an auxiliary steering angle to be subtracted from the front wheel steering angle.

  The case where the front wheel actuator 41 basically performs subtraction control is a high vehicle speed region. In the high vehicle speed range, the steering-yaw rate gain is high, and the influence of the change in responsiveness on the vehicle behavior is large. By performing the responsiveness change control in such a scene, the driver's steering burden can be reduced more effectively.

  (7) The responsiveness changing unit 5044c is executed when the four-wheel active steering control gives an auxiliary steering angle in phase with the front wheels with respect to the rear wheel steering angle.

  The case where the rear wheel actuator 51 basically performs in-phase control is a high vehicle speed region. In the high vehicle speed range, the steering-yaw rate gain is high, and the influence of the change in responsiveness on the vehicle behavior is large. By performing the responsiveness change control in such a scene, the driver's steering burden can be reduced more effectively.

  (8) The responsiveness estimation unit 5043 estimates responsiveness based on the relationship between the rotational speeds of the front wheel side motor 42 and the rear wheel side motor 52 and the output voltage to the front wheel side motor 42 and the rear wheel side motor 52. It was.

  If the motor speed does not increase despite the large output voltage Duty, it can be determined that the load on the actuator is large. If the load is large, it can be estimated that the responsiveness is lowered. In this way, it is possible to quickly determine a change in responsiveness by estimating the responsiveness based on information having a control phase earlier than the actual deviation between the target front wheel steering angle and the actual steering angle. .

  (9) The responsiveness estimation unit 5043 obtains responsiveness based on the relationship between the actual current value flowing through the front wheel side motor 42 and the rear wheel side motor 52 and the current command value to the front wheel side motor 42 and the rear wheel side motor 52. It was decided to estimate.

  The current command value is compared with the actual current value, and when the actual current value is larger than the current command value by a predetermined value P, it can be determined that an overcurrent is flowing. Since an overcurrent flows means that the steering load is large, it can be estimated that the responsiveness decreases. In this way, it is possible to quickly determine a change in responsiveness by estimating the responsiveness based on information having a control phase earlier than the actual deviation between the target front wheel steering angle and the actual steering angle. .

  (10) The responsiveness estimating unit 5043 estimates the responsiveness based on the integrated current command value to the front wheel side motor 42 and the rear wheel side motor 52.

  The temperature of the motor, the substrate, etc. can be roughly estimated from the flowing current. When the temperature exceeds a predetermined value, it is determined that an abnormality has occurred in the four-wheel active steering system, and active steer control is performed to reduce the responsiveness and execute control to suppress the temperature rise. . As described above, it is possible to estimate the decrease in the responsiveness by grasping in advance that the process for reducing the responsiveness is executed on the four-wheel active steering control side.

  Next, Example 2 will be described. Since the basic configuration is the same as that of the first embodiment, only different points will be described. In the first embodiment, the responsiveness change control process is executed only during the front wheel subtraction control + rear wheel in-phase control. In contrast, the second embodiment is different in that the responsiveness changing control process is executed also in the case of front wheel addition control + rear wheel in-phase control and in the case of front wheel addition control + rear wheel reverse phase control.

(Correction processing during additional steering)
Here, the correction process at the time of additional steering will be described. In the responsiveness change control process of the second embodiment, the responsiveness is changed even when the front wheel actuator 41 is performing addition control. As described above, scenes in which such combination control is performed are a low vehicle speed region and a medium vehicle speed region. This is because in a region where the steering-yaw rate gain is not so high, it can be said that there is a high demand for achieving a desired vehicle behavior by relatively generating yaw rate and lateral speed.

  FIG. 13A is a table showing the relationship between each responsiveness combination at the time of additional steering and the responsiveness changing process corresponding to the combination. When the steering is increased, the driver basically has the intention to turn, and it is necessary to generate a yaw rate or a lateral speed according to the traveling state.

[Front wheel addition control + rear wheel in-phase control]
When the response of the front wheel actuator 41 is lowered, the response of the rear wheel actuator 51 is lowered. In front wheel addition control and rear wheel in-phase control, if the responsiveness of front wheel addition control is reduced, it becomes slow, and a desired yaw rate and lateral speed cannot be obtained. Therefore, the cornering force of the rear wheel is lowered by reducing the responsiveness of the rear wheel in-phase control. As a result, the effect of generating the yaw rate and the lateral speed is enhanced, and as a result, the lack of behavior change accompanying the decrease in the response of the front wheel actuator 41 is absorbed and stabilized.

  When the responsiveness of the rear wheel actuator 51 is lowered, the responsiveness of the front wheel actuator 41 is lowered. In the front wheel addition control and the rear wheel in-phase control, if the responsiveness of the rear wheel in-phase control is lowered, the cornering force of the rear wheel is lowered, and a yaw rate and a lateral speed higher than desired are generated. Therefore, the cornering force of the front wheels is lowered by reducing the responsiveness of the front wheel addition control. As a result, the effect of suppressing the yaw rate and the lateral speed is enhanced, and as a result, the behavior change accompanying the decrease in the responsiveness of the rear wheel actuator 51 is absorbed and stabilized.

  When the response of the front wheel actuator 41 is increased, the response of the rear wheel actuator 51 is increased. In the front wheel addition control and the rear wheel in-phase control, when the response of the front wheel addition control is increased, it becomes quick, and a yaw rate or a lateral speed higher than desired is generated. Therefore, the cornering force of the rear wheel is increased by increasing the responsiveness of the rear wheel in-phase control. Thereby, the effect of suppressing the yaw rate and the lateral speed is enhanced, and as a result, the behavior change accompanying the increase in the response of the front wheel actuator 41 is absorbed and stabilized.

  When the response of the rear wheel actuator 51 is increased, the response of the front wheel actuator 41 is increased. In the front wheel addition control and the rear wheel in-phase control, when the responsiveness of the rear wheel in-phase control is increased, the cornering force of the rear wheel is increased, and a desired yaw rate and lateral speed cannot be obtained. Therefore, the cornering force of the front wheels is increased by increasing the responsiveness of the front wheel addition control. As a result, the effect of generating the yaw rate and the lateral speed is enhanced, and as a result, the insufficient behavior change accompanying the increase in the response of the rear wheel actuator 51 is absorbed and stabilized.

[Front wheel addition control + Rear wheel reverse phase control]
When the response of the front wheel actuator 41 decreases, the response of the rear wheel actuator 51 is increased. In front wheel addition control and rear wheel reverse phase control, if the responsiveness of the front wheel addition control decreases, it becomes slow, and a desired yaw rate and lateral speed cannot be obtained. Therefore, the cornering force of the rear wheel is lowered by increasing the responsiveness of the rear wheel reverse phase control. As a result, the effect of generating the yaw rate and the lateral speed is enhanced, and as a result, the lack of behavior change accompanying the decrease in the response of the front wheel actuator 41 is absorbed and stabilized.

  When the response of the rear wheel actuator 51 is lowered, the response of the front wheel actuator 41 is increased. In the front wheel addition control and the rear wheel reverse phase control, if the responsiveness of the rear wheel reverse phase control decreases, the cornering force of the rear wheel is unlikely to decrease, and a desired yaw rate and lateral speed cannot be obtained. Therefore, the cornering force of the front wheels is increased by increasing the responsiveness of the front wheel addition control. As a result, the effect of generating the yaw rate and the lateral speed is enhanced, and as a result, the lack of behavior change associated with the decrease in the response of the rear wheel actuator 51 is absorbed and stabilized.

  When the response of the front wheel actuator 41 is increased, the response of the rear wheel actuator 51 is decreased. In the front wheel addition control and the rear wheel reverse phase control, when the response of the front wheel addition control is increased, a quick operation is performed, and a yaw rate and a lateral speed higher than desired are generated. Therefore, the cornering force of the rear wheel is increased by reducing the responsiveness of the rear wheel reverse phase control. Thereby, the effect of suppressing the yaw rate and the lateral speed is enhanced, and as a result, the behavior change accompanying the increase in the response of the front wheel actuator 41 is absorbed and stabilized.

  When the response of the rear wheel actuator 51 is increased, the response of the front wheel actuator 41 is decreased. In the front wheel addition control and the rear wheel reverse phase control, when the responsiveness of the rear wheel reverse phase control is increased, the cornering force of the rear wheel is decreased, and a yaw rate and a lateral speed higher than desired are generated. Therefore, the cornering force of the front wheels is lowered by reducing the responsiveness of the front wheel addition control. As a result, the effect of suppressing the yaw rate and the lateral speed is enhanced, and as a result, the behavior change accompanying the increase in the responsiveness of the rear wheel actuator 51 is absorbed and stabilized.

(Correction processing during switchback steering)
Next, the correction process at the time of switching back steering will be described.
FIG. 13B is a table showing the relationship between each responsiveness combination at the time of switchback steering and the responsiveness changing process corresponding to the combination. At the time of switchback steering, the driver basically has an intention to end the turn, and it is necessary to reduce the yaw rate or the lateral speed according to the traveling state.

[Front wheel addition control + rear wheel in-phase control]
When the response of the front wheel actuator 41 decreases, the response of the rear wheel actuator 51 is increased. In front wheel addition control and rear wheel in-phase control, if the responsiveness of the front wheel addition control decreases, it becomes slow, and the yaw rate and lateral speed decrease are insufficient. Therefore, the cornering force of the rear wheel is lowered by increasing the responsiveness of the rear wheel in-phase control. As a result, the yaw rate suppression effect is enhanced, and as a result, the behavior convergence delay accompanying the decrease in the response of the front wheel actuator 41 is absorbed and stabilized.

  When the response of the rear wheel actuator 51 is lowered, the response of the front wheel actuator 41 is increased. In the front wheel addition control and the rear wheel in-phase control, if the responsiveness of the rear wheel in-phase control decreases, the yaw rate and the lateral speed decrease are delayed. Therefore, quickness is achieved by increasing the responsiveness of the front wheel addition control, and the cornering force of the front wheels is lowered. As a result, the yaw rate suppression effect is enhanced, and as a result, the behavior convergence delay accompanying the responsiveness reduction of the rear wheel actuator 51 is absorbed and stabilized.

  When the response of the front wheel actuator 41 is increased, the response of the rear wheel actuator 51 is decreased. In the front wheel addition control and the rear wheel in-phase control, when the response of the front wheel addition control is increased, the response becomes quick, and the yaw rate and the lateral speed decrease excessively, resulting in overshoot. Therefore, the cornering force of the rear wheel is increased by reducing the responsiveness of the rear wheel in-phase control. As a result, the yaw rate suppressing effect is enhanced, and as a result, the behavior convergence delay accompanying the increase in the response of the front wheel actuator 41 is absorbed and stabilized.

  When the response of the rear wheel actuator 51 is increased, the response of the front wheel actuator 41 is decreased. In the front wheel addition control and the rear wheel in-phase control, if the responsiveness of the rear wheel in-phase control increases, the yaw rate and the lateral speed decrease are delayed. Therefore, the cornering force of the front wheels is lowered by reducing the responsiveness of the front wheel addition control. As a result, the yaw rate suppressing effect is enhanced, and as a result, the behavior convergence delay accompanying the increase in the response of the rear wheel actuator 51 is absorbed and stabilized.

[Front wheel addition control + Rear wheel reverse phase control]
When the response of the front wheel actuator 41 is lowered, the response of the rear wheel actuator 51 is lowered. In front wheel addition control and rear wheel reverse phase control, if the responsiveness of the front wheel addition control is reduced, it becomes slow, and the yaw rate and lateral speed are not sufficiently reduced. Therefore, the cornering force of the rear wheel is lowered by reducing the responsiveness of the rear wheel reverse phase control. As a result, the effect of suppressing the yaw rate and the lateral speed is enhanced, and as a result, the behavior convergence delay accompanying the responsiveness reduction of the front wheel actuator 41 is absorbed and stabilized.

  When the responsiveness of the rear wheel actuator 51 is lowered, the responsiveness of the front wheel actuator 41 is lowered. In the front wheel addition control and the rear wheel reverse phase control, if the responsiveness of the rear wheel reverse phase control is reduced, the cornering force of the rear wheel is difficult to increase, and the yaw rate and the lateral speed are not sufficiently reduced. Therefore, the cornering force of the front wheels is lowered by reducing the responsiveness of the front wheel addition control. As a result, the effect of suppressing the yaw rate and the lateral speed is enhanced, and as a result, the behavior convergence delay accompanying the responsiveness reduction of the rear wheel actuator 51 is absorbed and stabilized.

  When the response of the front wheel actuator 41 is increased, the response of the rear wheel actuator 51 is increased. In the front wheel addition control and the rear wheel reverse phase control, when the response of the front wheel addition control is increased, the response becomes quick, and the yaw rate and the lateral speed decrease excessively, resulting in overshooting. Therefore, the cornering force of the rear wheel is increased by increasing the responsiveness of the rear wheel reverse phase control. Thereby, the effect of suppressing the yaw rate and the lateral speed is enhanced, and as a result, the behavior convergence delay accompanying the increase in the response of the front wheel actuator 41 is absorbed and stabilized.

  When the response of the rear wheel actuator 51 is increased, the response of the front wheel actuator 41 is increased. In the front wheel addition control and the rear wheel reverse phase control, when the responsiveness of the rear wheel reverse phase control is increased, the cornering force of the rear wheel is increased, and the yaw rate and the lateral speed are excessively decreased, resulting in overshooting. Therefore, the cornering force of the front wheels is lowered by increasing the responsiveness of the front wheel addition control. As a result, the effect of suppressing the yaw rate and the lateral speed is enhanced, and as a result, the behavior convergence delay accompanying the increase in the response of the rear wheel actuator 51 is absorbed and stabilized.

As described above, in the second embodiment, the following effects can be obtained.
(11) The responsiveness changing unit 5044c increases the responsiveness of the other when the detected steering state is further increased and the estimated responsiveness is reduced.

  In the second embodiment, in addition to the first embodiment, when the front wheel addition control and the rear wheel reverse phase control are assumed, for example, when the response of the front wheel actuator 41 is lowered, the response of the rear wheel actuator 51 is increased. Let As a result, the effect of generating the yaw rate and the lateral speed can be enhanced, and as a result, the lack of behavior change accompanying the decrease in the response of the front wheel actuator 41 can be absorbed and stabilized.

  Similarly, when the response of the rear wheel actuator 51 is lowered, the response of the front wheel actuator 41 is increased. As a result, the effect of generating the yaw rate and the lateral speed can be enhanced, and as a result, the lack of behavior change associated with the decrease in the responsiveness of the rear wheel actuator 51 can be absorbed and stabilized.

  (12) The responsiveness changing unit 5044c reduces the responsiveness of the other when the detected steering state is increased and the estimated responsiveness is increased when the detected steering state is increased.

  In the second embodiment, in addition to the first embodiment, when the front wheel addition control and the rear wheel reverse phase control are assumed, for example, when the response of the front wheel actuator 41 is increased, the response of the rear wheel actuator 51 is decreased. Let Thereby, the effect of suppressing the yaw rate and the lateral speed can be enhanced, and as a result, the behavior change accompanying the increase in the responsiveness of the front wheel actuator 41 can be absorbed and stabilized.

  Similarly, when the response of the rear wheel actuator 51 is increased, the response of the front wheel actuator 41 is decreased. Thereby, the effect of suppressing the yaw rate and the lateral speed can be enhanced, and as a result, the behavior change accompanying the increase in the responsiveness of the rear wheel actuator 51 can be absorbed and stabilized.

  (13) The responsiveness changing unit 5044c reduces the responsiveness of the other when the detected steering state is increased and the steering state is reduced and the estimated responsiveness is reduced.

  In the second embodiment, when the front wheel addition control and the rear wheel in-phase control are assumed, for example, when the response of the front wheel actuator 41 is reduced, the response of the rear wheel actuator 51 is reduced. As a result, the effect of generating the yaw rate and the lateral speed can be enhanced, and as a result, the lack of behavior change accompanying the decrease in the response of the front wheel actuator 41 can be absorbed and stabilized.

  Similarly, when the responsiveness of the rear wheel actuator 51 is lowered, the responsiveness of the front wheel actuator 41 is lowered. As a result, the effect of suppressing the yaw rate and the lateral speed can be enhanced, and as a result, the behavior change accompanying the decrease in the responsiveness of the rear wheel actuator 51 can be absorbed and stabilized.

  (14) The responsiveness changing unit 5044c increases the responsiveness of the other when the detected steering state is increased and the estimated responsiveness of the steering state is increased.

  In the second embodiment, when the front wheel addition control and the rear wheel in-phase control are assumed, for example, when the response of the front wheel actuator 41 is increased, the response of the rear wheel actuator 51 is increased. Thereby, the effect of suppressing the yaw rate and the lateral speed can be enhanced, and as a result, the behavior change accompanying the increase in the responsiveness of the front wheel actuator 41 can be absorbed and stabilized.

  Similarly, when the response of the rear wheel actuator 51 is increased, the response of the front wheel actuator 41 is increased. As a result, the effect of generating the yaw rate and the lateral speed can be enhanced, and as a result, the insufficient behavior change associated with the increased response of the rear wheel actuator 51 can be absorbed and stabilized.

  (15) When the detected steering state is the switching back steering state and one of the estimated responsiveness decreases, the responsiveness changing unit 5044c decreases the other responsiveness.

  In the second embodiment, in addition to the first embodiment, when the front wheel addition control and the rear wheel reverse phase control are assumed, for example, when the response of the front wheel actuator 41 decreases, the response of the rear wheel actuator 51 decreases. Let As a result, the effect of suppressing the yaw rate and the lateral speed can be enhanced, and as a result, the behavior convergence delay accompanying the responsiveness reduction of the front wheel actuator 41 can be absorbed and stabilized.

  Similarly, when the responsiveness of the rear wheel actuator 51 is lowered, the responsiveness of the front wheel actuator 41 is lowered. As a result, the effect of suppressing the yaw rate and the lateral speed can be enhanced, and as a result, the behavior convergence delay accompanying the responsiveness reduction of the rear wheel actuator 51 can be absorbed and stabilized.

  (16) When the detected steering state is the switchback steering state and one of the estimated responsiveness increases, the responsiveness changing unit 5044c increases the other responsiveness.

  In the second embodiment, in addition to the first embodiment, when the front wheel addition control and the rear wheel reverse phase control are assumed, for example, when the response of the front wheel actuator 41 is increased, the response of the rear wheel actuator 51 is increased. Let Thereby, the effect of suppressing the yaw rate and the lateral speed can be enhanced, and as a result, the behavior convergence delay accompanying the increase in the response of the front wheel actuator 41 can be absorbed and stabilized.

  Similarly, when the response of the rear wheel actuator 51 is increased, the response of the front wheel actuator 41 is increased. As a result, the effect of suppressing the yaw rate and the lateral speed can be enhanced, and as a result, the behavior convergence delay associated with the increased response of the rear wheel actuator 51 can be absorbed and stabilized.

  (17) The responsiveness changing unit 5044c increases the responsiveness of the other when the detected steering state is the switchback steering state and one of the estimated responsiveness decreases.

  In the second embodiment, when the front wheel addition control and the rear wheel in-phase control are assumed, for example, when the response of the front wheel actuator 41 is lowered, the response of the rear wheel actuator 51 is increased. As a result, the effect of suppressing the yaw rate can be enhanced, and as a result, the behavior convergence delay accompanying the decrease in the response of the front wheel actuator 41 can be absorbed and stabilized.

  Similarly, when the response of the rear wheel actuator 51 is lowered, the response of the front wheel actuator 41 is increased. As a result, the effect of suppressing the yaw rate can be enhanced, and as a result, the behavior convergence delay accompanying the responsiveness reduction of the rear wheel actuator 51 can be absorbed and stabilized.

  (18) When the detected steering state is the switchback steering state and one of the estimated responsiveness increases, the responsiveness changing unit 5044c decreases the other responsiveness.

  In the second embodiment, when the front wheel addition control and the rear wheel in-phase control are assumed, for example, when the response of the front wheel actuator 41 is increased, the response of the rear wheel actuator 51 is decreased. As a result, the effect of suppressing the yaw rate can be enhanced, and as a result, the behavior convergence delay accompanying the increase in the response of the front wheel actuator 41 can be absorbed and stabilized.

  Similarly, when the response of the rear wheel actuator 51 is increased, the response of the front wheel actuator 41 is decreased. Thereby, the effect of suppressing the yaw rate can be enhanced, and as a result, the behavior convergence delay accompanying the increase in the response of the rear wheel actuator 51 can be absorbed and stabilized.

1 is a system configuration diagram illustrating a vehicle control system in Embodiment 1. FIG. 1 is a system diagram illustrating a configuration of a four-wheel active steering system in Embodiment 1. FIG. It is a block diagram showing the control structure of the target value calculating part in Example 1. 3 is a block diagram illustrating a control configuration of an output correction unit in Embodiment 1. FIG. 6 is a flowchart illustrating a responsiveness change control process in a responsiveness change unit according to the first embodiment. 4 is a responsiveness determination map in which the rotational speed of the front wheel side motor in the first embodiment is the vertical axis and the front wheel side output voltage Duty is the horizontal axis. 3 is a responsiveness determination map in which the actual current value flowing to the front wheel side motor in the first embodiment is the vertical axis and the current command value to the front wheel side motor is the horizontal axis. 3 is a responsiveness determination map in which the temperature of the front wheel side motor (or a substrate such as a driver) in Example 1 is the vertical axis and the current command value integrated value to the front wheel side motor is the horizontal axis. It is a table | surface showing the relationship between the combination of each responsiveness in Example 1, and the responsiveness change process corresponding to the combination. 6 is a tuning parameter map for increasing the responsiveness in the first embodiment. 6 is a tuning parameter map in a case where responsiveness is lowered in the first embodiment. It is a simulation result showing the effect | action by the responsiveness change control process of Example 1. FIG. It is a table | surface showing the relationship of each responsiveness combination in Example 2, and the relationship of the responsiveness change process corresponding to the combination.

Explanation of symbols

1 Engine controller (ECU)
2 Automatic transmission controller (ATCU)
3 Meter controller (MCU)
4a Front wheel 4 Front wheel controller 5a Rear wheel 5 Rear wheel controller 6 Brake controller 7 Steering angle sensor 8 Integrated sensor 9 Brake controller 40 Front wheel steering unit 41 Front wheel actuator 50 Rear wheel steering unit 51 Rear wheel actuator

Claims (11)

Front wheel side active steering means for giving an auxiliary steering angle to the front wheels;
A rear wheel side active steering means for providing an auxiliary steering angle to the rear wheel;
Four-wheel active steer control means for commanding an auxiliary steering angle to both the active steer means so as to obtain desired vehicle behavior characteristics;
In a four-wheel active steering system with
Steering state detecting means for detecting the steering state of the driver;
Responsiveness estimating means for estimating the responsiveness of at least one of the front wheel side and rear wheel side active steering means;
Responsiveness changing means for changing the responsiveness of the other in response to the detected steering state and the estimated change in the responsiveness of the one;
A four-wheel active steering system. The four-wheel active steering system according to claim 1,
The responsiveness changing means is a combination of the detected steering state in which the detected steering state is increased and the front wheel side active steering means performs subtraction control, the rear wheel side active steering means is in-phase control, or the front wheel side active steering. When the means is a combination control and the rear wheel side active steer means is a combination of reverse-phase control, when one of the estimated responsiveness decreases, the other responsiveness is increased. . The four-wheel active steering system according to claim 1 or 2,
The responsiveness changing means is a combination of the detected steering state in which the detected steering state is increased and the front wheel side active steering means performs subtraction control, the rear wheel side active steering means is in-phase control, or the front wheel side active steering. In the case where the means is a combination control and the rear wheel side active steer means is a combination of the reverse-phase control, when the estimated response of one side increases, the response of the other wheel decreases. system. The four-wheel active steering system according to any one of claims 1 to 3,
The responsiveness changing means is a combination of the detected steering state being a switchback steering state, wherein the front wheel side active steer means is a subtraction control, the rear wheel side active steer means is a combination of in-phase control, or a front wheel side active steer. In the case where the means is a combination control and the rear wheel side active steer means is a combination of reverse phase control, when the estimated response of one of the four wheels is reduced, the response of the other wheel is reduced. system. The four-wheel active steering system according to any one of claims 1 to 4,
The responsiveness changing means is a combination of the detected steering state being a switchback steering state, wherein the front wheel side active steer means is a subtraction control, the rear wheel side active steer means is a combination of in-phase control, or a front wheel side active steer. In the case where the means is a combination control and the rear wheel side active steer means is a combination of reverse phase control, when the estimated response of one of the four wheels is increased, the response of the other is increased. system. The four-wheel active steering system according to any one of claims 1 to 5,
The responsiveness changing means is executed when the front-wheel side active steering means is in subtraction control. The four-wheel active steering system according to any one of claims 1 to 6,
The responsiveness changing means is executed when the rear wheel side active steering means is in-phase control. The four-wheel active steering system according to any one of claims 1 to 7,
The front wheel side and rear wheel side active steering means are means having an electric motor,
The four-wheel active steering system, wherein the responsiveness estimating means estimates responsiveness based on a relationship between a rotation speed of the electric motor and an output voltage to the electric motor. The four-wheel active steering system according to any one of claims 1 to 8,
The front wheel side and rear wheel side active steering means are means having an electric motor,
The four-wheel active steering system, wherein the responsiveness estimation means estimates responsiveness based on a relationship between an actual current value flowing through the electric motor and a current command value to the electric motor. The four-wheel active steering system according to any one of claims 1 to 9,
The front wheel side and rear wheel side active steering means are means having an electric motor,
The four-wheel active steering system according to claim 1, wherein the responsiveness estimating means estimates responsiveness based on a current command value integrated value to the electric motor. Front wheel side active steering means for giving an auxiliary steering angle to the front wheels;
A rear wheel side active steering means for providing an auxiliary steering angle to the rear wheel;
Four-wheel active steer control means for commanding an auxiliary steering angle to both the active steer means so as to obtain desired vehicle behavior characteristics;
In a four-wheel active steering system with
4. A four-wheel active steering system, wherein the response of the other active steering means is changed according to a steering state of the driver and a change in response of the one of the active steering means.

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