JP5228937B2 - Behavior control device - Google Patents

Description

  The present invention relates to a behavior control apparatus capable of controlling a turning angle of a wheel to bring an actual yaw rate closer to a target yaw rate when the vehicle is turning.

  Generally, when a vehicle turns, the behavior of the vehicle may be in an oversteer state due to excessive steering of the steering wheel or slipping of the road surface. A technique for suppressing such oversteer of a vehicle is described in Patent Document 1. The vehicle described in Patent Document 1 has a configuration in which the turning angle of the left and right front wheels is controlled in accordance with the rotation operation of the steering wheel. At that time, the steering angle by the steering wheel is automatically adjusted by the steering angle correction device. The left and right front wheels are steered at the automatically corrected turning angle. Further, the vehicle is provided with an electronic control device, and a signal indicating the vehicle speed, a signal indicating the yaw rate, a signal indicating the lateral acceleration of the vehicle body, a signal indicating the steering angle of the steering wheel, etc. are input to the electronic control device. .

  When the steering angle of the steering wheel is equal to or greater than a predetermined value, the yaw rate of the vehicle body, that is, the target yaw rate is obtained from signals such as the vehicle speed and the lateral acceleration of the vehicle body. Then, the actual yaw rate required by the yaw rate sensor is compared with the target yaw rate, and the actual steered angle is automatically reduced so that the actual yaw rate approaches the target yaw rate, thereby suppressing vehicle oversteer. To do. In addition, when control is performed to automatically reduce the turning angle of the wheel, if the driver performs an operation to return the steering wheel, that is, counter-steering, the steering angle of the wheel is automatically reduced. It is described that the control amount of control is reduced. A behavior control apparatus that controls the yaw rate when the vehicle is turning is also described in Patent Document 2.

JP 2007-131296 A JP-A-8-332971

  However, in the behavior control device described in Patent Document 1, when the driver performs counter-steering in order to correct the vehicle state when a disturbance occurs, the steering angle of the steering wheel is reduced. In addition, if the control amount for controlling the turning angle of the wheels is reduced, there is a possibility that the driver may feel uncomfortable.

  The present invention has been made in the background of the above circumstances, and provides a behavior control device capable of avoiding the driver from feeling uncomfortable with the behavior of the vehicle when performing control to bring the actual yaw rate close to the target yaw rate. It is an object.

  In order to achieve the above object, the invention according to claim 1 obtains a steering angle of a steering device operated by a driver of a vehicle, obtains a target yaw rate when the vehicle turns, based on the steering angle, In the behavior control device for controlling the turning angle of the wheels of the vehicle so that the actual yaw rate when the vehicle is turning is close to the target yaw rate, the behavior change of the vehicle caused by disturbance when the vehicle is turning Counter steer determining means for determining whether or not counter steer for returning the steering device in the direction of decreasing the steering angle has been performed, and counter steer for returning the steering device by the counter steer determining means. If it is determined that it has been performed, select the target yaw rate that was required before that time. And it is characterized in that it comprises a yaw rate selection means.

  According to the first aspect of the invention, in order to correct the change in the behavior of the vehicle caused by the disturbance when the vehicle is turning, the counter steer is performed to return the steering device in the direction of decreasing the steering angle. Can select the target yaw rate obtained before the determination time, and can control the turning angle of the wheels so that the actual yaw rate approaches the target yaw rate. Therefore, it is possible to prevent the target yaw rate from being obtained using the change in the steering angle due to the disturbance, and it is possible to avoid the driver's uncomfortable feeling.

It is a flowchart which shows the example of control of this invention. It is a conceptual diagram of the vehicle which can perform the example of control shown in FIG. It is an example of the table used at the process step of the flowchart of FIG. It is another example of the table used at the process step of the flowchart of FIG. It is a conceptual diagram which shows the other vehicle which can perform the example of control shown in FIG.

  Next, a configuration example of a vehicle capable of executing the control of the present invention will be described with reference to FIG. The vehicle A shown in FIG. 2 has wheels, specifically, a left front wheel 1, a right front wheel 2, a left rear wheel 3, and a right rear wheel 4. An electric motor 5 that drives the left front wheel 1 is attached to the wheel of the left front wheel 1, and an electric motor 6 that drives the right front wheel 2 is attached to the wheel of the right front wheel 2, An electric motor 7 that drives the left rear wheel 3 is attached to the wheel of the left rear wheel 3, and an electric motor 8 that drives the right rear wheel 4 is attached to the wheel of the right rear wheel 4. Yes. That is, all four wheels are in-wheel motor type wheels. A power storage device (not shown) is mounted on the vehicle body of the vehicle A, and power running control can be performed by supplying electric power from the power storage device to each electric motor. On the contrary, it is also possible to generate electricity with each electric motor during repulsive running of the vehicle A and charge the power storage device with the electric power. As the power storage device, a secondary battery that can be charged and discharged, more specifically, a battery or a capacitor can be used. The vehicle A is a four-wheel drive vehicle capable of controlling the distribution of driving force generated between the left and right wheels or between the front wheels and the rear wheels.

  Further, the left front wheel 1 and the right front wheel 2 are supported by a suspension (not shown), and are configured such that the turning angle can be changed. A steering angle control device 12 for controlling the steering angles of the left front wheel 1 and the right front wheel 2 is provided. Further, as shown in FIG. 3, a steering wheel 20 is provided, and the steering wheel 20 is connected to the rudder angle control device 12 so that power can be transmitted. The steering wheel 20 is operated by the driver and can rotate within a predetermined angle range around the rotation axis. The steering angle control device 12 is a mechanism that converts the rotational force of the steering wheel 20 into the steering force of the front wheels. Thereby, the operating force of the steering wheel 20 is transmitted to the left front wheel 1 and the right front wheel 2, and the turning angle of each wheel is changed. Further, the rudder angle control device 12 can perform control for making the steered angles of the left front wheel 1 and the right front wheel 2 coincide with the steering angle obtained from the operation amount of the steering wheel 20 or making it different. As this rudder angle control apparatus 12, what has actuators, such as an electric motor or a hydraulic cylinder, is used, for example. Since this type of rudder angle control device 12 is known as disclosed in, for example, Japanese Patent Laid-Open Nos. 6-336172 and 5-24553, its specific illustration and description are provided. Is omitted.

  Furthermore, a vehicle electronic control unit (ECU) 9 for controlling the steering angle control device 12 is provided, and a motor electronic control unit (ECU) 10 for controlling each electric motor is provided. The vehicle electronic control device 9 includes a steering angle sensor signal for detecting the operation amount of the steering wheel 20, a torque sensor signal for detecting an operation force (torque) applied to the steering wheel 20, and a vehicle A longitudinal direction. A sensor 13 signal for detecting acceleration and lateral acceleration, a yaw rate around the center of gravity of the vehicle A, a sensor signal for detecting the vehicle speed, a sensor signal for detecting the accelerator opening, and the like are input. Further, the navigation system 14 is mounted on the vehicle A. The navigation system 14 is an apparatus that can detect the current position of the vehicle A, input a destination of the vehicle A, and perform an operation of searching for a planned travel route of the vehicle A. Signals are exchanged between the electronic control device for controlling the navigation system 14 and the vehicle electronic control device 9, and signals are exchanged between the motor electronic control device 10 and the vehicle electronic control device 9. This is the configuration that is performed.

  Next, a control example executed by the vehicle A shown in FIG. 2 will be described. First, the target driving force in the vehicle A is obtained based on the vehicle speed and the accelerator opening, and the torque and the rotational speed of each electric motor are controlled based on the target driving force. Further, during traveling of the vehicle A, the steering angle is obtained from the operation amount of the steering wheel 20, and the turning angles of the left front wheel 1 and the right front wheel 2 are controlled based on the steering angle. Thereby, the vehicle A can perform straight traveling and turning. Further, in this embodiment, during traveling of the vehicle A, in order to bring the actual yaw rate of the vehicle A closer to the target yaw rate, the steering angle corresponding to the operation amount of the steering wheel 20 and the steering angle of the front wheels are made to match or be different. Control can be performed.

Next, an example of control performed during traveling of the vehicle A, specifically, during turning traveling will be described based on the flowchart of FIG. First, the norm (target) yaw rate γref is calculated based on Equation (1) (step S1).
γref = [V / {(1 + KhrefV ² ) L}] (θ / n) (1)
Here, V is the vehicle speed, Khref is the target stability factor, and L is the foil base. This target stability factor is a value for setting the behavior of the vehicle A when turning to a steer characteristic such as oversteer, neutral steer, or understeer.

  Whether or not the driver has performed a counter-steer to correct the behavior of the vehicle A when disturbance (for example, rear-slip of the rear wheel) occurs during the turning of the vehicle A and the oversteer characteristic is strengthened. It is determined (step S2). Here, the counter steer is an operation of rotating in a direction to reduce the steering angle of the steering wheel 20 from a state where the steering wheel 20 is steered in either the left or right direction. In this step S2, the operation state of the steering wheel 20 of the driver and the state of the vehicle A are comprehensively determined. For the determination in step S2, the tables shown in FIGS. 3 and 4 are used.

  Specifically, the state of the steering wheel 20 is determined based on the value of θ × Gy and the value of θ × dθ / dt using the table of FIG. Here, θ is a steering angle obtained from the operation amount of the steering wheel 20 (hereinafter referred to as a steering angle of the steering wheel 20), Gy is a lateral acceleration of the vehicle, and dθ / dt is the steering wheel 20 Is a time differential value of the steering angle. The steering angle of the steering wheel 20 is a rotation angle with respect to the neutral position, and FIG. 3 illustrates the steering angle when the steering wheel 20 is rotated leftward. When θ × Gy exceeds zero degree and θ × dθ / dt exceeds zero degree, the steering angle of the steering wheel 20 to the left is increasing (increase) (case 1). judge. In addition, when θ × Gy exceeds zero degree and θ × dθ / dt is equal to or less than zero degree, it is determined that the steering wheel 20 is switched back (case 2). This return means that the increased steering wheel 20 is returned toward the neutral position.

  On the other hand, when θ × Gy is equal to or less than zero degrees and θ × dθ / dt exceeds zero degrees, it is determined that the steering wheel 20 is turned back (case 3). Here, “turning back” means that the steering wheel 20 is steered in the right direction after passing through the neutral position by the turning back. Further, when θ × Gy is equal to or less than zero degrees and θ × dθ / dt is equal to or less than zero degrees, it is determined that the counter is returned (case 4). Here, the counter return means that the steering wheel 20 turned back to the right is rotated leftward toward the neutral position.

  In the table of FIG. 4, the state (steer characteristic) of the vehicle A is determined based on the value of yaw × dβ / dt. Here, yaw is the yaw rate, and dβ / dt is the time differential value of the slip angle β. Here, the slip angle β is an acute angle formed by the center line X in the width direction when the vehicle A travels straight and the center line Y in the width direction when the vehicle A turns. If yaw × dβ / dt is equal to or greater than zero degrees, it is determined that the yaw rate has increased and the slip angle β has decreased. This means that the vehicle A turns with an understeer (US) tendency. On the other hand, when yaw × dβ / dt is less than zero degrees, it is determined that the yaw rate has increased and the slip angle β has increased. This means that the vehicle A turns with an oversteer (OS) tendency.

  Following the step S2, it is determined whether or not the steering wheel 20 is in a counter steer state (counter steer is being performed) (step S3). Here, in the table of FIG. 3, when it is determined that it is either case 2 or case 3 or case 4, and in the table of FIG. 4, it is determined that yaw × dβ / dt is less than zero, A positive determination is made in step S3, and a negative determination is made in step S3 under other conditions.

  If a positive determination is made in step S3, it is determined whether or not a positive determination was made in step S3 when this control routine was executed last time (step S4). If a negative determination is made in step S4, the target yaw rate obtained in step S1 during the current execution of the control routine is saved (stored) (step S11), and the process proceeds to step S5. In step S5, the target yaw rate stored in step S11 is selected as the target yaw rate for controlling the actual yaw rate, and this control routine is terminated. In contrast, if the determination in step S4 is affirmative, the process proceeds to step S5.

  On the other hand, if a negative determination is made in step S3, it is determined whether or not a positive determination was made in step S3 when this control routine was executed last time (step S21). If a negative determination is made in step S21, the control routine is terminated. If a positive determination is made in step S21, the target yaw rate is obtained from the equation (1) used in step S1 (step S22). This control routine is terminated. In this embodiment, the steering angle of the front wheels is controlled by the steering angle control device 12 so that the actual yaw rate approaches the target yaw rate obtained in step S5 or step S22. 3 and 4 show an example in which the vehicle A turns left, but the control shown in FIG. 1 can also be executed when the vehicle A turns right. In this case, the steering direction of the steering wheel 20 described with reference to the tables of FIGS. 3 and 4 is reversed between right and left.

  In the control example of FIG. 1, when the vehicle A is turning, the oversteer characteristic of the vehicle A is strengthened by disturbance, and the driver counter-steers the steering wheel 20 in order to correct the behavior. The actual yaw rate is controlled using the target yaw rate obtained in the routine before that time. Note that the “before that time” includes the time itself. Therefore, the change in the steering angle of the steering wheel 20 due to the disturbance can be prevented from being used as the target yaw rate calculation data, and the driver's uncomfortable feeling can be avoided.

  Next, a configuration example of a vehicle capable of executing the control example of FIG. 1 will be described with reference to FIG. 5, the same components as those in FIG. 1 are denoted by the same reference numerals as those in FIG. In a vehicle B in FIG. 5, a transmission 16 is connected to an engine 15 so that power can be transmitted, and a differential 18 is connected to the transmission 16 via a propeller shaft 17 so that power can be transmitted. The left rear wheel 3 and the right rear wheel 4 are connected to the differential 18. The differential 18 is configured to be able to control the distribution ratio of power transmitted to the left rear wheel 3 and the right rear wheel 4. Here, differentials capable of controlling the distribution of torque transmitted to the left and right wheels or the front and rear wheels are known as described in, for example, Japanese Patent Laid-Open Nos. 5-301573 and 6-92157. Therefore, illustration and description of the configuration are omitted.

  Also, a differential electronic control device 19 is provided for controlling the distribution of torque transmitted from the differential 18 to the left and right rear wheels. A signal is transmitted between the differential electronic control device 19 and the vehicle electronic control device 9. It is the structure where exchange of is performed. Thus, the vehicle B shown in FIG. 5 is a two-wheel drive vehicle capable of controlling the distribution of torque transmitted to the left and right rear wheels. Also in the vehicle B shown in FIG. 5, the control example of FIG. 1 can be executed.

  Here, the correspondence between the functional means shown in FIG. 1 and the configuration of the present invention will be described. Step S3 corresponds to the counter steer determination means of the present invention, and step S4, step S11 and step S5 are This corresponds to the yaw rate selection means of the present invention. The steering wheel 20 corresponds to the steering device of the present invention, and the left front wheel 1 and the right front wheel 2 correspond to the wheels (steering wheels) of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Left front wheel, 2 ... Right front wheel, 20 ... Steering wheel, A, B ... Vehicle.

Claims (1)

A steering angle of a steering device operated by a driver of the vehicle is obtained, a target yaw rate when the vehicle is turning is obtained based on the steering angle, and an actual yaw rate when the vehicle is turning is set as the target yaw rate. In the behavior control device that controls the turning angle of the wheel of the vehicle so as to approach,
Counter steer determination for determining whether or not a counter steer for returning the steering device in a direction to decrease the steering angle has been performed in order to correct a change in behavior of the vehicle caused by disturbance when the vehicle is turning. Means,
When it is determined that the counter steer returning the steering device has been performed by the counter steer determination unit, the counter steer determination unit includes a yaw rate selection unit that selects a target yaw rate obtained before the determination point. Behavior control device.

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