JP2006143011A - Vehicle behavior control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle behavior control device, steering rear wheels in consideration of operability and riding comfortableness according to the riding status of a fellow passenger. <P>SOLUTION: This vehicle behavior control device 1 for steering the rear wheels includes: a fellow passenger detecting means 2 for detecting a fellow passenger; a vehicle behavior detecting means 4 for detecting the quantity of state showing the behavior of the turning vehicle; a rear wheel target steering angle setting means 6 for setting the target steering angle of the rear wheels according to the quantity of state detected by the vehicle behavior detecting means 3; a change rate setting means 6 for setting the change rate of the steering angle of the rear wheels to the quantity of state detected by the vehicle behavior detecting means 4 and reducing the change rate of the steering angle of the rear wheels when a fellow passenger is detected by the fellow passenger detecting means 2; and rear wheel steering means 5, 6 for steering the rear wheels by the change rate set by the change rate setting means 6 to reach the target steering angle set by the rear wheel target steering angle setting means 6. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle behavior control apparatus that steers rear wheels.

Some vehicle behavior control devices perform steering control of rear wheels in order to improve vehicle stability and responsiveness. In the rear wheel steering device, for example, the rear wheel steering amount is set based on the yaw rate of the vehicle, and the rear wheel is steered in a direction to suppress the yaw rate according to the set steering amount (see Patent Document 1). By steering the rear wheels in this way, the convergence of the yaw rate when the vehicle turns is improved, and the running stability of the vehicle is improved.
JP-A-5-131946

  However, by steering the rear wheel in accordance with the yaw rate, the cornering force of the rear wheel is accelerated, and the lateral acceleration of the vehicle body suddenly rises (that is, the lateral jerk increases). As a result, the roll angular velocity of the vehicle body increases. For the passengers, the change in the roll angular velocity cannot be predicted, so that the passenger feels uncomfortable (that is, the riding comfort is deteriorated). Therefore, in the rear wheel steering control device disclosed in Patent Document 1, the rear wheel steering correction amount is set based on the roll angle or roll angular velocity of the vehicle body, and the steering correction amount is set to the yaw rate with respect to the rear wheel steering amount. In the direction opposite to the direction of suppressing By correcting in this way, the rise of the lateral acceleration becomes dull (that is, the lateral jerk becomes small), and the roll angular velocity is kept small. As a result, ride comfort is improved.

  Further, in the rear wheel steering device, since the lateral jerk is increased by steering the rear wheel, the driver's response to the steering wheel operation is improved. Therefore, the operability during steering is improved for the driver. On the other hand, in the rear wheel steering control device, since correction is always performed based on the roll angle or roll angular velocity, the lateral jerk is reduced and the operability is lowered.

  Accordingly, an object of the present invention is to provide a vehicle behavior control device that steers the rear wheels in consideration of operability and riding comfort according to the passenger's riding situation.

  The vehicle behavior control apparatus according to the present invention includes passenger detection means for detecting a passenger, vehicle behavior detection means for detecting a state quantity indicating the behavior of the vehicle during a turn, and state quantities detected by the vehicle behavior detection means. Based on the rear wheel target steering angle setting means for setting the target steering angle of the rear wheel based on the state quantity detected by the vehicle behavior detecting means, the rate of change of the steering angle of the rear wheel with respect to the state quantity detected by the vehicle behavior detecting means is set. Change rate setting means for reducing the change rate when detected, and rear wheel steering for steering the rear wheels at the change rate set by the change rate setting means so as to be the target steering angle set by the rear wheel target steering angle setting means Means.

  In this vehicle behavior control device, a state quantity indicating the behavior of the vehicle during a turn is detected by the vehicle behavior detection means, and a rear wheel target steering angle setting means sets the rear wheel target steering angle based on the detected state quantity. At the same time, the change rate setting means sets the change rate of the steering angle of the rear wheels with respect to the detected state quantity. In the vehicle behavior control device, the rear wheels are steered by the change rate of the steering angle of the rear wheels set so as to be the target steering angle by the rear wheel steering means. Further, in the vehicle behavior control device, whether or not there is a passenger is detected by the passenger detection means. When there is a passenger, the vehicle behavior control device reduces the rate of change of the steering angle of the rear wheel by the rate of change setting means, and gradually changes the rear wheel from the normal (that is, reduces the steering angular velocity of the rear wheel). . As a result, the rear wheels are steered more slowly than usual, so the rise of the lateral acceleration becomes dull and the lateral jerk is reduced. As a result, the roll angular velocity is kept small, and the riding comfort is improved. On the other hand, when there is no passenger, the rear wheels are steered quickly, so that the lateral acceleration suddenly rises and the lateral jerk increases. As a result, the responsiveness to the driver's steering operation is improved, and the operability during steering is improved. Thus, in this vehicle behavior control apparatus, riding comfort and operability can be improved according to the passenger's boarding situation.

  Note that the state quantity indicating the behavior of the vehicle that is turning changes when the vehicle is turning and represents the behavior of the vehicle, such as the steering angle and yaw rate of the front wheels. Reducing the rate of change in the steering angle of the rear wheel means reducing the speed at which the rear wheel is steered. For example, by reducing the control gain, the steering amount of the rear wheel per unit time is reduced. Or, the maximum control amount per time when the rear wheel is steered is reduced. Reducing the change rate of the steering angle of the rear wheels includes not steering the rear wheels at all.

  In the vehicle behavior control apparatus of the present invention, the state quantity of the vehicle behavior is the steering angle of the front wheels, and the rear wheel target steering angle setting means is configured to perform the target steering of the rear wheels when the steering angle of the front wheels is larger than when the steering angle is small. It is preferable to set the angle so as to increase in phase with the steering angle of the front wheels.

  In this vehicle behavior control device, the steering angle of the front wheels is detected by the vehicle behavior detection means, and the target steering angle of the rear wheels is set based on the steering angle of the front wheels by the rear wheel target steering angle setting means. At this time, the target steering angle is set so as to be larger when the steering angle of the front wheel is larger than when the steering angle of the front wheel is small. In the vehicle behavior control apparatus, the rear wheels are steered in phase with the front wheels so that the target steering angle is obtained by the rear wheel steering means. As a result, since the rear wheels are steered in phase with the front wheels, an increase in the yaw moment generated in the vehicle can be reduced, and the side slip angle of the vehicle body can be reduced.

  In the vehicle behavior control device according to the present invention, the state quantity of the vehicle behavior is the vehicle yaw rate, and the rear wheel target steering angle setting means sets the rear wheel target steering angle when the vehicle yaw rate is larger than when the vehicle yaw rate is small. It is preferable to set it to be large in phase with the front wheel.

  In this vehicle behavior control device, the yaw rate is detected by the vehicle behavior detection means, and the rear wheel target steering angle setting means sets the rear wheel target steering angle based on the yaw rate. At this time, the target steering angle is set to be larger when the yaw rate is larger than when the yaw rate is smaller, in phase with the front wheels. In the vehicle behavior control apparatus, the rear wheels are steered in phase with the front wheels so that the target steering angle is obtained by the rear wheel steering means. As a result, the side slip angle of the vehicle body can be reduced as described above.

  According to the present invention, when the passenger is present, the lateral jerk can be reduced by reducing the rate of change in the steering angle of the rear wheel, thereby improving the riding comfort. The operability during steering can be improved by increasing.

  Hereinafter, an embodiment of a vehicle behavior control device according to the present invention will be described with reference to the drawings.

  In the present embodiment, the vehicle behavior control device according to the present invention is applied to a rear wheel steering device that steers rear wheels. The rear wheel steering device according to the present embodiment sets the target steering angle of the rear wheels based on the steering angle of the front wheels. Furthermore, the rear wheel steering system according to the present embodiment detects a passenger by attaching and detaching a seat belt, and when there is a passenger, a control gain (steering angular velocity proportional gain) for setting a target steering angle is obtained. By making it smaller, the rate of change in the steering angle of the rear wheels is reduced. In the present embodiment, the direction of the steering angle is represented by positive and negative, a positive value is the right rotation direction of the wheel, and a negative value is the left rotation direction of the wheel.

  With reference to FIG. 1, the structure of the rear-wheel steering apparatus 1 which concerns on this Embodiment is demonstrated. FIG. 1 is a configuration diagram of a rear wheel steering apparatus according to the present embodiment.

  The rear wheel steering device 1 steers the rear wheels according to the steering angle of the front wheels so that the side slip angle of the vehicle body becomes zero in order to improve operability and stability during steering. In particular, the rear wheel steering device 1 reduces the rate of change of the steering angle of the rear wheels in order to improve the riding comfort when the passenger is on the vehicle. For this purpose, the rear wheel steering device 1 includes a seating sensor 2, a vehicle speed sensor 3, a front wheel steering angle sensor 4, a rear wheel steering actuator 5, and an ECU [Electronic Control Unit] 6.

  In the present embodiment, the seating sensor 2 corresponds to the passenger detection means described in the claims, the front wheel steering angle sensor 4 corresponds to the vehicle behavior detection means described in the claims, and the ECU 6 The rear wheel steering actuator 5 and the ECU 6 correspond to the rear wheel steering means described in the claims, and correspond to the rear wheel target steering angle setting means and the change rate setting means described in the claims.

  The seating sensor 2 is a sensor that detects the attachment / detachment of the seat belt of each seat, and detects on / off of a switch (a switch that is turned on when the seat belt plate is inserted into the buckle) provided in the seat belt buckle. To do. The seating sensor 2 transmits the on / off to the ECU 6 as a seating signal DS. The seating sensors 2 are provided in all seats provided with seat belts, but the rear wheel steering device 1 uses the seating sensors 2 for seats other than the driver's seat.

  The vehicle speed sensor 3 is a sensor that detects the speed of the vehicle, and transmits the detected value to the ECU 6 as a vehicle speed signal SS. The front wheel steering angle sensor 4 is a sensor that detects the steering angle of the front wheels, and transmits the detected value to the ECU 6 as a steering angle signal AS.

  The rear wheel steering actuator 5 is a motor that is provided on a rack shaft coupled to the rear wheel and moves the rack shaft in the vehicle width direction. The rear wheel steering actuator 5 is supplied with a control current CC from the ECU 6, rotates in the forward rotation direction or the reverse rotation direction in accordance with the direction in which the control current CC flows, and rotates at a rotation speed in accordance with the magnitude of the control current CC. For example, when the rear wheel steering actuator 5 is rotated in the forward direction, the rack shaft is moved to the left. When the rear wheel steering actuator 5 is rotated in the forward direction, the rack shaft is moved to the left. When the rear wheel is steered in the clockwise direction and the rear wheel steering actuator 5 is rotated in the reverse direction, the rack shaft is moved in the right direction and the rear wheel is steered in the left direction. .

  The ECU 6 is an electronic control unit including a CPU [Central Processing Unit], a ROM [Read Only Memory], a RAM [Random Access Memory], an actuator drive circuit, and the like, and functions as a control device of the rear wheel steering device 1. The ECU 6 takes the seating signal DS, the vehicle speed signal SS, and the steering angle signal AS from the seating sensor 2, the vehicle speed sensor 3, and the front wheel steering angle sensor 4, and performs passenger presence / absence control processing, rear wheel steering control processing, etc. The drive of the steering actuator 5 is controlled.

  The passenger presence / absence control process will be described. In the ECU 6, when the vehicle speed obtained from the vehicle speed signal SS becomes greater than 0 (when the vehicle is traveling), the on / off information obtained from the respective seating signals DS of the seating sensors 2 of the seats other than the driver's seat. It is determined whether or not a passenger is present in each seat from (that is, seat belt attachment / detachment information). When all of the seating signals DS are off, the ECU 6 determines that there is no passenger, and sets 0 to the passenger flag. On the other hand, if there is at least one seating signal among the seating signals DS, the ECU 6 determines that there is a passenger and sets 1 to the passenger flag. The passenger flag is a flag indicating whether or not there is a person (passenger) riding in the vehicle other than the driver, and is 1 when there is a passenger, and 0 when there is no passenger. is there.

  The rear wheel steering control process will be described. The ECU 6 determines whether or not the passenger flag is 0. When the passenger flag is 0 (when only the driver is in the vehicle), the ECU 6 sets the target steering angle = AS × GP + AS × GD × s (AS: front wheel steering angle, GP: steering angle proportional gain, GD: steering angular velocity) The target steering angle of the rear wheel is obtained by performing an operation of proportional gain, s: Laplace operator). On the other hand, when the passenger flag is 1 (when a passenger other than the driver is in the vehicle), the ECU 6 performs the calculation of target steering angle = AS × GP + AS × (1/4) GD × s, Find the target steering angle for the rear wheels. The ECU 6 determines the steering direction of the front wheels based on the sign of the steering angle of the front wheels, and determines the steering direction of the rear wheels so as to be in phase with the front wheels. Further, the ECU 6 sets a target control current based on the target steering angle and steering direction of the rear wheels. At this time, the target steering angle obtained by calculation is used, and the target control current is set to increase as the target steering angle increases. Further, the larger the steering angular velocity proportional gain GD, the larger the target control current is set, and the amount of change in the rear wheel turning angle becomes larger. Conversely, the smaller the steering angular velocity proportional gain GD, the smaller the target control current is set and the smaller the change amount of the rear wheel turning angle. In the actuator drive circuit of the ECU 6, the control current CC is supplied to the rear wheel steering actuator 5 so that the target control current is obtained.

  The steering angle proportional gain GP and the steering angular velocity proportional gain GD, which are control gains, are based on a control law for setting the side slip angle of the vehicle body to zero. When there is a passenger, the ECU 6 reduces the steering angular velocity proportional gain GD without changing the steering angular proportional gain GP. By reducing the steering angular velocity proportional gain GD, the amount of change in the target control current can be reduced, and the size of the rear wheel turning angle (the rear wheel turning angular velocity) to be changed per unit time can be reduced. The time until the target steering angle is reached becomes longer. Further, since the steering angle proportional gain GP is not changed, the final rear wheel turning angle value does not change when no passenger is present.

  With reference to FIG. 1, the operation | movement in the rear-wheel steering apparatus 1 is demonstrated. In particular, the passenger presence / absence control process in the ECU 6 will be described with reference to the flowchart of FIG. 2, and the rear wheel steering control process will be described with reference to the flowchart of FIG. FIG. 2 is a flowchart showing the flow of the passenger presence / absence control process in the ECU of FIG. FIG. 3 is a flowchart showing a flow of rear wheel steering control processing in the ECU of FIG.

  Each seating sensor 2 detects on / off of a switch in the buckle of each seat belt, and transmits a seating signal DS to the ECU 6. The vehicle speed sensor 3 detects the vehicle speed and transmits a vehicle speed signal SS to the ECU 6. The front wheel steering angle sensor 4 detects the steering angle of the front wheels and transmits a steering angle signal AS to the ECU 6.

  The ECU 6 acquires the vehicle speed from the vehicle speed signal SS (S10). Further, the ECU 6 acquires seat belt attachment / detachment information from the on / off information of each seating signal DS (S11). Then, the ECU 6 determines whether or not the vehicle speed is greater than 0 (S12). When the vehicle speed is determined to be 0 in S12, the process returns to S10.

  On the other hand, if it is determined in S12 that the vehicle speed is greater than 0, the ECU 6 determines whether there is a passenger based on the seat belt attachment / detachment information (S13). When it is determined in S13 that there is a passenger, the ECU 6 sets 1 to the passenger flag (S14). On the other hand, when it is determined in S13 that there is no passenger, the ECU 6 sets 0 to the passenger flag (S15).

  Then, the ECU 6 determines whether or not the ignition switch is turned on (S16). If it is determined that the ignition switch is turned on in S16, the process returns to S10 to continue the process, and if it is not turned on in S16. If so, the process ends.

  Further, the ECU 6 acquires the front wheel steering angle AS from the steering angle signal AS (S20). The ECU 6 sets a steering angle proportional gain GP and a steering angular velocity proportional gain GD (S21).

  The ECU 6 determines whether or not the fellow passenger flag is 1 (S21). If it is determined in S21 that the fellow passenger flag is 0, the process proceeds to S24 as it is. When the passenger flag is determined to be 1 in S21, the ECU 6 changes the value of the steering angular velocity proportional gain GD to GD × 1/4 (S23).

  Then, the ECU 6 obtains the target steering angle of the rear wheels by the calculation of target steering angle = AS × GP + AS × GD × s (S24). When the front wheels are not being steered, the target steering angle is 0. When the front wheels are being steered, the target steering angle is a value corresponding to the steering angle of the front wheels. Further, the ECU 6 determines the steering direction from the positive / negative of the steering angle of the front wheels, and obtains the steering direction when steering the rear wheels from the steering direction of the front wheels. Then, the ECU 6 sets a target control current from the target steering angle and steering direction of the rear wheel, and supplies the control current CC to the rear wheel steering actuator 5 so as to be the target control current (S25). Incidentally, when the front wheel is not steered, the ECU 6 does not supply the control current CC to the rear wheel steering actuator 5.

  Then, the rear wheel steering actuator 5 is driven to rotate in the forward rotation direction or the reverse rotation direction according to the control current CC, and the rack shaft is moved in the left direction or the right direction. When the rack shaft moves leftward or rightward, the rear wheel rotates rightward or leftward. At this time, the rear wheels are steered in phase with the front wheels, and as the steering angle of the front wheels increases, the steering angle of the rear wheels also increases, so that an increase in yaw moment generated in the vehicle is suppressed, and the side slip angle of the vehicle body becomes zero. To be reduced.

  When only the driver is in the vehicle, the control gain is set so that the side slip angle of the vehicle body becomes 0. Therefore, the rear wheel turns quickly according to the steering of the front wheel, and according to the steering of the front wheel. The lateral acceleration of the vehicle changes with good responsiveness. On the other hand, when a passenger other than the driver is on board, the steering angular velocity proportional gain GD is 1/4 of the normal, so the rear wheels gradually steer according to the steering of the front wheels, Lateral acceleration changes gradually. Thereby, the roll angular velocity of the vehicle body can be kept small.

  FIG. 4 shows a temporal change in the lateral acceleration of the vehicle body when the front wheels are steered and the rear wheels are steered by the rear wheel steering device 1. The solid line shows the change when the rear wheel is steered with the normal steering angular velocity proportional gain GD (when only the driver is in the vehicle), the start-up is abrupt, and the response is good. On the other hand, the broken line shows the change when the rear wheel is steered by one-fourth of the normal steering angular velocity proportional gain GD (when a passenger is on board other than the driver), and the start-up becomes dull. Yes.

  FIG. 5 shows the time change of the lateral jerk (differential of the lateral acceleration) of the vehicle body when the front wheels are steered and the rear wheels are steered by the rear wheel steering device 1. The solid line shows the change when the rear wheels are steered with the normal steering angular velocity proportional gain GD, and the peak value is large. Thus, the larger the lateral jerk, the better the response performance and the operability of the driver during steering. By the way, the larger the lateral jerk, the greater the roll angular velocity of the car body, but the driver can predict that, so it doesn't feel uncomfortable. On the other hand, the broken line shows the change when the rear wheel is steered at a quarter of the normal steering angular velocity proportional gain GD, and the peak value is small. Thus, the smaller the lateral jerk, the smaller the roll angular velocity of the vehicle body and the better the ride comfort.

  According to the rear wheel steering device 1, the operability can be improved when only the driver is present, and the ride comfort can be improved when the passenger is present. Comfort can be improved. The rear wheel steering device 1 determines the presence / absence of a passenger from the information on the attachment / detachment of the seat belt, and when there is a passenger, the normal steering angular velocity proportional gain GD is simply reduced to a quarter. Control is realized.

  As mentioned above, although embodiment which concerns on this invention was described, this invention is implemented in various forms, without being limited to the said embodiment.

  For example, in the present embodiment, the steering angular velocity proportional gain GD is set to 1/4 in order to reduce the rate of change in the steering angle of the rear wheels when a passenger is present. It may be changed to other than 1, or the steering angular velocity proportional gain GD may not be changed, but if a passenger is present, the rear wheel may not be steered, or the rear wheel steering actuator (and The maximum control amount of the rear wheel steering angle may be reduced.

  In the present embodiment, the control law is such that the side slip angle of the vehicle body becomes zero, but the control law that makes the side slip angle of the vehicle body within several degrees or the control law that makes the side jerk below a predetermined value. Other control laws may be used.

  In this embodiment, the rear wheel steering is controlled based on the steering angle of the front wheels. However, the steering of the rear wheels is controlled based on the state quantity indicating the behavior of the vehicle during other turning such as the yaw rate. It is good also as composition to do. When the rear wheels are steered based on the yaw rate, it is preferable that the target steering angle of the rear wheels is set to be large in phase with the front wheels when the yaw rate is larger than when the yaw rate is small.

  In the present embodiment, the passenger is detected by attaching and detaching the seat belt. However, the passenger may be detected by another detection method such as a suspension stroke or a vehicle acceleration performance.

  In the present embodiment, the rear wheel target steering angle is obtained by calculation using the front wheel steering angle. However, the ECU maintains a map and the rear wheel according to the steering angle of the front wheel based on the map. The target steering angle may be set.

It is a lineblock diagram of the rear-wheel steering device concerning this embodiment. It is a flowchart which shows the flow of the passenger presence / absence control processing in ECU of FIG. 3 is a flowchart showing a flow of rear wheel steering control processing in the ECU of FIG. 1. 2 is a graph showing a temporal change in lateral acceleration when a front wheel is steered in a vehicle equipped with the rear wheel steering device of FIG. 1. It is a graph which shows the time change of a horizontal jerk when the front wheel in the vehicle carrying the rear-wheel steering apparatus of FIG. 1 is steered.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Rear-wheel steering apparatus, 2 ... Seating sensor, 3 ... Vehicle speed sensor, 4 ... Front-wheel steering angle sensor, 5 ... Rear-wheel steering actuator, 6 ... ECU

Claims (3)

Passenger detection means for detecting a passenger,
Vehicle behavior detecting means for detecting a state quantity indicating the behavior of the vehicle during a turn;
Rear wheel target steering angle setting means for setting a target steering angle of the rear wheel based on the state quantity detected by the vehicle behavior detection means;
A change rate setting means for setting a change rate of a steering angle of a rear wheel with respect to a state quantity detected by the vehicle behavior detecting means, and for reducing the change rate when a passenger is detected by the passenger detection means;
A vehicle behavior control device comprising: rear wheel steering means for steering the rear wheels at a change rate set by the change rate setting means so as to achieve a target steering angle set by the rear wheel target steering angle setting means. . The state quantity of the behavior of the vehicle is the steering angle of the front wheels,
2. The rear wheel target steering angle setting means sets the target steering angle of the rear wheel so as to increase in phase with the steering angle of the front wheel when the steering angle of the front wheel is larger than when it is small. The vehicle behavior control device described. The state quantity of the behavior of the vehicle is a yaw rate of the vehicle,
2. The vehicle according to claim 1, wherein the rear wheel target steering angle setting means sets the target steering angle of the rear wheel so as to increase in phase with the front wheels when the yaw rate of the vehicle is larger than when it is small. Behavior control device.

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