JP2006347238A - Backward turn controller for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a backward turn controller of a vehicle improved in turning performance in backward traveling while being achieved in a low cost system, and achieved in high operability in garage parking or serial parking. <P>SOLUTION: This vehicle is provided with a system in which at least one of driving forces and braking forces of right and left rear wheels RR and RL are independently controllable is provided with a backward-turn travel detecting means (step S1, step S5) for detecting backward turn traveling and a backward turn control means for performing control to apply a braking/driving force for suppressing tire rotation at the turn inner wheel side of the right and left rear wheels RR and RL in backward turn traveling. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention belongs to a technical field of a reverse turning control device for a vehicle including a system capable of independently controlling at least one of a driving force and a braking force of left and right rear wheels on the left and right sides.

As a conventional technique for improving the turning performance, there is four-wheel steering. This system is a technique for giving a turning angle to the rear wheels in accordance with steering (see, for example, Patent Document 1).
JP-A-9-104354

  However, the conventional four-wheel steering device requires a dedicated control system and a rear-wheel steering mechanism to give the steering angle to the rear wheels, which increases the cost and puts the garage in a small space. In parallel parking, etc., when turning backward, multiple turning operations may be required due to the limit of the minimum turning radius, and the driver's turning performance improvement request (reduction of the minimum turning radius that does not require turning operation) is achieved. There was a problem of not getting.

  The present invention has been made by paying attention to the above-mentioned problems, and is a low-cost system, which improves the turning performance at the time of reversing, and allows the vehicle to retreat which can obtain high maneuverability in garage storage or parallel parking. An object is to provide a turning control device.

In order to achieve the above object, in the present invention, in a vehicle equipped with a system capable of independently controlling at least one of the driving force and the braking force of the left and right rear wheels, respectively,
Reverse turning traveling detection means for detecting backward turning traveling;
A reverse turning control means for performing a control to apply a braking / driving force for suppressing the tire rotation on the turning inner wheel side of the left and right rear wheels during reverse turning; and
It is provided with.

  Therefore, in the reverse turning control device for a vehicle according to the present invention, the control for applying the braking / driving force for suppressing the tire rotation on the turning inner wheel side of the left and right rear wheels is performed in the reverse turning control means during reverse turning. Is called. That is, by suppressing tire rotation on the turning inner wheel side of the left and right rear wheels, the turning center position moves from a position determined by the rudder angle of the left and right front wheels to a position close to the turning inner wheel of the left and right rear wheels. Reduction of the radius of rotation is achieved by applying force. As a result, while making a low-cost system, the turning performance at the time of reverse can be improved, and high maneuverability in garage storage or parallel parking can be obtained.

  BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the best mode for carrying out a vehicle reverse turning control apparatus according to the present invention will be described based on Example 1 and Example 2 shown in the drawings.

First, the configuration will be described.
FIG. 1 is an overall system diagram showing a rear motor vehicle to which the reverse turning control device of the first embodiment is applied.
As shown in FIG. 1, the reverse turning control device of the first embodiment includes a CPU 101, a shift switch 102, a wheel speed sensor 103, a wheel speed sensor 104, a steering angle sensor 105 (steering angle detection means), and a motor. 106 and a motor 107.

  The shift switch 102 is means for detecting backward movement from the driver's shift operation, and the CPU 101 determines the start of control based on this signal.

  The wheel speed sensors 103 and 104 detect wheel speeds (= actual axle rotation speeds) of the left and right rear wheels RR and RL, respectively. The CPU 101 detects a tire slip from the difference between the left and right actual axle rotation speeds output by the wheel speed sensors 103 and 104 (slip detection means). Further, the CPU 101 detects the vehicle speed from the average value of the actual axle rotation right and left (vehicle speed detection means).

  The steering angle sensor 105 is attached to the rotating shaft of the steering device and detects the steering angle. The CPU 101 determines the driving torque of the left and right rear wheels RR and RL with respect to the steering angle from the steering angle and the vehicle speed, and instructs the motors 106 and 107 for the driving torque.

  The motors 106 and 107 receive a request from the CPU 101 and generate driving torque on the axles of the left and right rear wheels RR and RL.

  The CPU 101 detects reverse (R range) by the shift switch 102 and starts reverse turning control. Further, it is determined whether or not reverse turning control is possible based on the vehicle speed. Further, the reverse turning control is stopped at the time of slip determination. Further, the driving torque of the left and right rear wheels RR and RL with respect to the steering angle is determined from the steering angle and the vehicle speed, and the respective driving torques are instructed to the motors 106 and 107.

Next, the operation will be described.
[Reverse turning control processing]
FIG. 2 is a flowchart showing the flow of the reverse turning control process executed by the CPU 101 of the first embodiment. Each step will be described below (reverse turning control means).

  In step S1, it is determined whether or not a reverse range (= R range) is detected by the shift switch 102. If Yes, the process proceeds to step S2, and if No, the determination in step S1 is repeated.

  In step S2, following the detection of the R range in step S1, pulse signals of the actual axle speeds of the left and right rear wheels RR and RL are detected from the wheel speed sensors 103 and 104, and the process proceeds to step S3.

In step S3, following the detection of the actual axle speed in step S2, the vehicle speed and the difference between the left and right axle speeds are calculated, and the process proceeds to step S4.
Here, the vehicle speed is calculated from the average value of the actual axle speed of the right rear RR and the actual axle speed of the left rear wheel RL. Further, the difference between the left and right axle rotational speeds is calculated by the difference between the actual axle rotational speed of the right rear RR and the actual axle rotational speed of the left rear wheel RL.

  In step S4, following the vehicle speed and axle speed difference calculation in step S3, the steering angle information is detected from the steering angle sensor 105, and the process proceeds to step S5.

In step S5, following the detection of the steering angle in step S4, it is determined whether control is possible based on the vehicle speed and the steering angle. If yes, the process proceeds to step S6, and if no, the process proceeds to step S7.
This step S5 is a determination step for avoiding unnecessary reduction of the turning radius that is not desired by the driver, that is, when the vehicle speed is high and the vehicle moves backward with a large turning radius, not garage storage or parallel parking. It is determined that the reverse turning control is possible when the control permission vehicle speed (for example, about 15 km / h) or less and the steering angle is equal to or greater than the control permission steering angle (for example, steering wheel angle of about 180 °).

In step S6, following the controllable determination based on the vehicle speed and the steering angle in step S5, it is determined whether there is no tire slip. If Yes, the process proceeds to step S8, and if No, the process proceeds to step S7.
Here, the presence / absence determination of tire slip is determined as no tire slip when the difference between the left and right axle rotational speeds calculated in step S3 is a slip determination threshold set in advance according to the turning radius as follows. In other words, because a difference in the inner and outer ring speeds occurs depending on the turning radius during turning, the value obtained by adding a set value to the difference between the inner and outer ring speeds is used as a slip judgment threshold value, and tire slip does not occur when the slip judgment threshold value is not exceeded. Is determined.

  In step S7, following the control impossibility determination based on the vehicle speed and the steering angle in step S5 or the slip presence determination in step S6, the reverse turning control by the drive torque distribution is stopped, and the process proceeds to return.

In step S8, following the determination of no tire slip in step S6, the drive torque distribution of the left and right rear wheels RR and RL with respect to the steering angle is calculated from the steering angle and the vehicle speed, and the process proceeds to step S9.
Here, the drive torque distribution of the left and right rear wheels RR, RL is, for the turning outer wheel of the left and right rear wheels RR, RL, for example, a driving torque that allows the vehicle to travel backward according to the accelerator operation amount, and for the turning inner wheel, The larger the rudder angle and the lower the vehicle speed, the larger the reverse torque (forward running side torque) is generated as the driving torque.

  In step S9, following the drive torque distribution calculation in step S8, the motors 106 and 107 that drive the left and right rear wheels RR and RL are instructed to obtain the calculated drive torque distribution and return to return. Transition.

[Reverse turning control operation]
If the conditions for allowing reverse turning control (vehicle speed, rudder angle condition, and no slip condition) are satisfied at the time of reverse in garage entry or parallel parking, etc., step S1 → step S2 → The flow proceeds from step S3 to step S4 to step S5 to step S6 to step S8 to step S9. In step S9, the motors 106 and 107 that drive the left and right rear wheels RR and RL are driven in step S8. Each drive torque is commanded to obtain a torque distribution.

  On the other hand, when the vehicle speed and the steering angle condition are not satisfied among the conditions for permitting the reverse turning control, in the flowchart of FIG. 2, the flow proceeds from step S1, step S2, step S3, step S4, step S5, and step S7. Become. Further, when the slip-free condition is not satisfied among the conditions for permitting the reverse turning control, in the flowchart of FIG. 2, the flow proceeds to step S1, step S2, step S3, step S4, step S5, step S6, and step S7. It becomes. In any case, in step S7, the reverse turning control by the drive torque distribution is stopped.

[Reverse turning control action]
As described above, when the conditions for permitting the reverse turning control are satisfied when the vehicle is reversing in a garage, parallel parking, or the like, the inner wheels are turned to the motors 106 and 107 that drive the left and right rear wheels RR and RL. A driving torque for generating reverse torque (forward running side torque) is instructed. That is, by generating a reverse torque on the turning inner wheel side of the left and right rear wheels RR, RL and suppressing tire rotation, the turning center position of the left and right rear wheels RR, RL is changed from the position determined by the steering angle of the left and right front wheels. Moving to a position close to the turning inner wheel, reduction of the turning radius is achieved by applying drive torque (reverse torque). Therefore, the turning performance (small turning performance) at the time of reverse can be improved, and high maneuverability in garage entry or parallel parking can be obtained.

  In addition, the larger the rudder angle of the left and right rear wheels RR and RL, the larger the reverse steering torque is generated and the tire rotation is suppressed. The wheel RR, RL can move to a position closer to the turning inner wheel, and the minimum turning radius can be reduced. Conversely, when the driver intends to turn with a large radius, the steering angle of the left and right front wheels at the turning center position The amount of movement from the position determined by is reduced, and unnecessary reduction of the turning radius that is not desired by the driver can be avoided.

  Furthermore, on a low μ road such as a snowy road, if the wheel speed difference is larger than the wheel speed difference due to the turning radius and vehicle speed of the left and right rear wheels RR, RL, or if the tire on the turning inner wheel side is generating reverse torque, When the vehicle rotates in the forward direction, it is determined that the vehicle is slipping, and the reverse turning control is stopped. Therefore, the stability of the reverse turning traveling can be ensured on a low μ road such as a snowy road. In other words, if a large reverse torque is generated on the turning inner wheel side of the left and right rear wheels RR, RL on a low μ road, there is a possibility that the vehicle will behave more excessively than the driver expects. Stability is impaired.

  In addition, since the reverse turning control is stopped during reverse turning at a high speed as in the case of reverse running at a high speed on a gentle curve, the stability of the reverse turning can be ensured. In other words, when a large reverse torque is generated on the turning inner wheel side of the left and right rear wheels RR, RL when traveling backward at high speed, the driver can cut inward from the turning line aimed by the driver and trace the aimed turning line. The steering stability is lost.

Next, the effect will be described.
In the reverse turning control device for a vehicle according to the first embodiment, the effects listed below can be obtained.

  (1) In a vehicle equipped with a system that can independently control at least one of the driving force and braking force of the left and right rear wheels RR and RL on the left and right sides, a reverse turning detection means (step S1, step for detecting reverse turning) S5) and reverse turning control means for performing control for applying braking / driving force for suppressing tire rotation on the turning inner wheel side of the left and right rear wheels RR and RL during reverse turning, and is already mounted. While being a low-cost system using a braking / driving force system, it is possible to improve the turning performance when reversing and to obtain high maneuverability in garage storage or parallel parking.

  (2) The vehicle is a rear motor vehicle including motors 106 and 107 capable of independently controlling the driving forces of the left and right rear wheels RR and RL, and the reverse turning control means includes the left and right rear wheels RR and RL. In order to control the tire rotation by generating reverse torque on the turning inner wheel side, the driving power of the left and right rear wheels RR, RL is controlled independently, so that high maneuverability in garage storage and parallel parking etc. It is possible to improve the small turning performance during the reverse operation.

  (3) A steering angle sensor 105 for detecting a steering angle is provided, and the reverse turning control means rotates the tire on the turning inner wheel side of the left and right rear wheels RR and RL as the steering steering angle increases during backward turning. Since the control for applying the driving force that increases the degree of suppression is performed, it is possible to achieve the small turning performance that meets the turning radius reduction request that appears in the steering angle while avoiding unnecessary reduction of the turning radius that the driver does not want.

  (4) Provide slip detection means for detecting tire slip of the left and right rear wheels RR, RL, and the reverse turning control means, when judging that tire slip occurs during reverse turning, of the left and right rear wheels RR, RL Since the driving force control for suppressing the tire rotation on the turning inner wheel side is stopped, the vehicle behavior stability in the backward turning traveling can be ensured on the low μ road.

  (5) A vehicle speed detection means for detecting the vehicle speed is provided, and the reverse turning control means, when traveling backward, when the detected vehicle speed value exceeds the control limit vehicle speed, of the left and right rear wheels RR, RL Since driving force control that suppresses tire rotation is stopped, steering stability can be ensured during reverse turning at high speed.

  The second embodiment is an application example to a brake-by-wire vehicle in which the braking forces of the left and right rear wheels RR and RL are independently controlled.

  First, the configuration will be described. As shown in FIG. 3, the backward turning control device of the second embodiment includes a CPU 101, a shift switch 102, a wheel speed sensor 103, a wheel speed sensor 104, and a steering angle sensor 105 (steering). Angle detection means), a brake CPU 108, a brake 109, and a brake 110.

  The brake CPU 108 supplies to the brakes 109 and 110 a command for obtaining the braking force instructed by the wheel to be controlled instructed by the CPU 101. Here, when the brakes 109 and 110 are hydraulic brakes, a command by hydraulic pressure is issued from the brake CPU 108, and when the brakes 109 and 110 are motor brakes, a motor drive command is issued from the brake CPU 108.

  The brakes 109 and 110 receive a request from the CPU 101 and generate a braking force on the left and right rear wheels RR and RL.

  The CPU 101 detects reverse (R range) by the shift switch 102 and starts reverse turning control. Further, it is determined whether or not reverse turning control is possible based on the vehicle speed. Further, the reverse turning control is stopped at the time of slip determination. Further, the braking torque on the turning inner wheel side to be controlled among the left and right rear wheels RR, RL is determined from the steering angle and the vehicle speed, and the brake CPU 108 is instructed to apply the braking torque to the brake 109 or 110 of the target wheel. Since other configurations are the same as those in the first embodiment, description thereof is omitted.

Next, the operation will be described.
[Reverse turning control processing]
FIG. 4 is a flowchart showing the flow of the reverse turning control process executed by the CPU 101 and the brake CPU 108 of the second embodiment. Each step will be described below (reverse turning control means). Steps S21 to S27 are the same processing steps corresponding to steps S1 to S7 in FIG.

In step S28, following the determination of no tire slip in step S26, the braking force (= braking torque) of the control target wheel (turning inner wheel) out of the left and right rear wheels RR, RL is calculated from the rudder angle and the vehicle speed. The process proceeds to S29.
Here, a larger braking force is calculated for the wheel to be controlled as the rudder angle is larger and the vehicle speed is lower.

  In step S29, following the brake force calculation for the control target wheel in step S28, an instruction to brake the control target wheel with the calculated brake force is issued to the brake CPU 108, and the process proceeds to step S30.

  In step S30, following the brake force instruction in step S29, the brake force is output from the brake 109 or 110 that brakes the wheel to be controlled (turning inner wheel) in accordance with an instruction from the brake CPU 108, and the process proceeds to return.

[Reverse turning control operation]
If the conditions for allowing reverse turning control (vehicle speed, rudder angle condition, and no slip condition) are satisfied at the time of reverse in garage storage or parallel parking, etc., step S21 → step S22 → The flow proceeds from step S23 → step S24 → step S25 → step S26 → step S28 → step S29 → step S30. In step S30, in response to an instruction from the brake CPU 108, the brake 109 or the brake 109 that brakes the control target wheel (turning inner wheel). A braking force is output from 110.

  On the other hand, when the vehicle speed and the steering angle condition are not satisfied among the permission conditions for the reverse turning control, in the flowchart of FIG. 4, the process proceeds from step S21 → step S22 → step S23 → step S24 → step S25 → step S27. Become. If the slip-free condition is not satisfied among the reverse turning control permission conditions, the flow proceeds to step S21 → step S22 → step S23 → step S24 → step S25 → step S26 → step S27 in the flowchart of FIG. It becomes. In any case, in step S27, the reverse turning control by applying the braking force to the wheel to be controlled is stopped.

[Reverse turning control action]
As described above, if the conditions for permitting reverse turning control are satisfied when the vehicle is reversing in a garage or parallel parking, among the brakes 109 and 110 that brake the left and right rear wheels RR and RL, An instruction to generate a braking force is given to the brake of the turning inner wheel that is a wheel. That is, by generating a braking force on the turning inner wheel side of the left and right rear wheels RR, RL and suppressing the tire rotation, the turning center position is changed from the position determined by the steering angle of the left and right front wheels to the left and right rear wheels RR, RL. It moves to a position close to the turning inner wheel, and the turning radius is reduced by applying a braking force. Therefore, the turning performance (small turning performance) at the time of reverse can be improved, and high maneuverability in garage entry or parallel parking can be obtained.

  In addition, the larger the rudder angle on the turning inner wheel side of the left and right rear wheels RR, RL, the greater the braking force is generated and the tire rotation is suppressed. When the driver intends to turn at a large radius, the brake force is small and the steering of the left and right front wheels is reduced. The amount of movement from the turning center position determined by the angle is reduced, and unnecessary reduction of the turning radius that the driver does not want can be avoided. Since other operations are the same as those in the first embodiment, description thereof is omitted.

Next, the effect will be described.
In the vehicle reverse turning control device of the second embodiment, in addition to the effects (1), (3), (4), (5) of the first embodiment, the following effects can be obtained.

  (6) The vehicle is a brake-by-wire vehicle equipped with brakes 109 and 110 capable of independently controlling the braking forces of the left and right rear wheels RR and RL, and the reverse turning control means includes the left and right rear wheels RR and RL. Of these, in order to control the tire rotation by generating braking force on the turning inner wheel side, out of the left and right rear wheels RR, RL, by applying braking force only to the turning inner wheel that is the controlled wheel, It is possible to improve the small turning performance at the time of reverse, which exhibits high maneuverability in parallel parking or the like.

  As mentioned above, although the reverse turning control apparatus of the vehicle of this invention was demonstrated based on Example 1 and Example 2, it is not restricted to these Examples about a concrete structure, Each of a claim Design changes and additions are permitted without departing from the scope of the claimed invention.

  In the first and second embodiments, as the reverse turning control means, during reverse turning, a braking / driving force is applied to increase the degree of suppression of tire rotation on the turning inner wheel side of the left and right rear wheels RR, RL as the steering steering angle increases. For example, when it is recognized that it is a parking operation at a parking lot (even when GPS is recognized, it is recognized by a driver's switch operation), a braking force or drive is applied to the turning inner wheel side by a fixed value. A force (reverse torque) may be applied. In short, any means for controlling the braking / driving force to suppress the tire rotation on the turning inner wheel side of the left and right rear wheels during reverse turning traveling can be applied to the present invention. included.

  In the first and second embodiments, the reverse turning control device is applied to a rear motor vehicle and a brake-by-wire vehicle. However, for example, a rear motor vehicle with a brake-by-wire may be used, and at least one of the driving force and the braking force of the left and right rear wheels is used. Any vehicle other than the first and second embodiments can be used as long as the vehicle includes a system that can be independently controlled on the left and right.

1 is an overall system diagram showing a rear motor vehicle to which a reverse turning control device of Embodiment 1 is applied. It is a flowchart which shows the flow of the reverse turning control process performed by CPU of Example 1. FIG. It is a whole system figure which shows the brake-by-wire vehicle to which the reverse turning control apparatus of Example 2 was applied. It is a flowchart which shows the flow of the reverse turning control process performed by CPU and brake CPU of Example 2. FIG.

Explanation of symbols

101 CPU
102 Shift switches 103, 104 Wheel speed sensor 105 Steering angle sensor (steering angle detection means)
106,107 Motor 108 Brake CPU
109,110 brake

Claims (6)

In a vehicle equipped with a system that can independently control at least one of the driving force and braking force of the left and right rear wheels,
Reverse turning traveling detection means for detecting backward turning traveling;
A reverse turning control means for performing a control to apply a braking / driving force for suppressing the tire rotation on the turning inner wheel side of the left and right rear wheels during reverse turning; and
A reverse turning control device for a vehicle, comprising: In the vehicle reverse turning control device according to claim 1,
The vehicle is a rear motor vehicle including a motor capable of independently controlling the driving forces of the left and right rear wheels,
The reverse turning control device for a vehicle, wherein the reverse turning control means performs control to generate a reverse torque on the inner turning side of the left and right rear wheels to suppress tire rotation. In the vehicle reverse turning control device according to claim 1 or 2,
The vehicle is a brake-by-wire vehicle equipped with a brake capable of independently controlling the braking force of the left and right rear wheels,
The backward turning control device for a vehicle, characterized in that the backward turning control means performs control to generate a braking force on the inner turning side of the left and right rear wheels to suppress tire rotation. The reverse turning control device for a vehicle according to any one of claims 1 to 3,
A steering angle detecting means for detecting a steering angle is provided;
The reverse turning control means performs control to apply a braking / driving force that increases the degree of suppressing the rotation of the tire on the turning inner wheel side of the left and right rear wheels as the steering steering angle increases during reverse turning. A reverse turning control device for a vehicle. The vehicle reverse turning control device according to any one of claims 1 to 4,
Slip detection means for detecting the tire slip of the left and right rear wheels is provided,
The reverse turning control means stops the braking / driving force control for suppressing the tire rotation on the turning inner wheel side of the left and right rear wheels when it is determined that tire slip occurs during reverse turning. Swivel control device. The vehicle reverse turning control device according to any one of claims 1 to 5,
Vehicle speed detecting means for detecting the vehicle speed is provided;
The reverse turning control means stops braking / driving force control for suppressing tire rotation on the turning inner wheel side of the left and right rear wheels when the vehicle speed detection value exceeds the control limit vehicle speed during reverse turning. A reverse turning control device for a vehicle.

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