REAR WHEEL STEERING CONTROL DEVICE

• US 20120277956A1
• Filed: 11/12/2010
• Published: 11/01/2012
• Est. Priority Date: 11/16/2009
• Status: Active Grant

• Current Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Original Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Inventors: Horiuchi, Yutaka, Sasaki, Hitoshi, Hinohara, Takamichi
• Granted Patent: US 8,433,478 B2
• Time in Patent Office: Days
• US Class Current: 701/41
• CPC Class Codes: B62D 7/159 characterised by computing methods or stabilisation processes or systems, e.g. responding to yaw rate, lateral wind, load, road condition

Abstract

Generally, the toe angle target speed limiting unit (84A) adds a toe angle target value α_T2P subjected to the primary delay to the result of a min-max processing the tracking error Δα_T1A by an adder (58A) to output it as a toe angle target value α_T2A to a target current calculating unit (86). However, in this toe angle target speed limiting unit (84A), a switching control (steering direction change control) for generating a maximum value Δα_Tmax as the toe angle target change quantity Δα_T2 and a hold control are made when a neutral position of the toe angle target value α_T2A which is prior to the toe angle command value α_T1 which is reached.

Claims

1. A rear wheel steering control device comprising an actuator configured to change a steering angle of a rear wheel installed in a vehicle and a control unit configured to control driving the actuator, capable of changing a steering angle of the rear wheel, wherein:

the control unit comprises;

an actuator control unit configured to control the actuator;

a steering angle command value calculating unit configured to calculate a steering angle command value of the rear wheel on the basis of at least a turning state quantity of a front wheel;

a target value setting updating unit configured to perform a target value updating control by setting a steering angle target value of the rear wheel inputted into the actuator control unit in response to the value of the steering command value of the rear wheel inputted from the steering angle command calculating unit; and

a command value increase and decrease direction determining unit configured to determine an increase and decrease direction of the calculated steering angle command of the rear wheel, wherein

the target value setting updating unit calculates a difference between the steering angle command value of the rear wheel and the steering angel target value of the rear wheel last set as well as limits the calculated target value change quantity to be equal to or lower than a predetermined maximum value at needs and is added to a steering angle target value of the rear wheel last set as a new steering angle target value of the rear wheels; and

when the command value increase and decrease direction determining unit detects that the increase and decrease direction of the steering angle command value of the rear wheel changes, the command value increase and decrease direction determining unit sets the target value change quantity in a direction opposite to the action of the actuator and to a predetermine maximum value to have a maximum speed, which is added to the steering angle target value of the rear wheel last set to conduct a target value updating control.

2. The rear wheel steering control device as claimed in claim 1, wherein after the target value setting updating unit starts the target value updating control by detecting change in the increase and decrease direction of the steering angle command value of the rear wheel, at timing when it is detected that the steering angle target value of the rear wheel reaches a neutral position, when the inputted steering angle command value of the rear wheel has not reached a neutral position, the target value setting updating unit sets the steering angle target value of the rear wheel to hold the steering angle target value of the rear wheel at the neutral position for the target value updating control.

3. A rear wheel steering control device comprising an actuator configured to change a steering angle of a rear wheel installed in a vehicle and a control unit configured to control driving the actuator, capable of changing a steering angle of the rear wheel, wherein:

the control unit comprises;

an actuator control unit configured to control the actuator;

a command value calculating unit configured to calculate a steering angle command value of the rear wheel on the basis of at least a turning state quantity of a front wheel;

a target value speed limiting unit configured to receive an input of a turning command value of the rear wheel inputted from the command value calculating unit and set a first target value change quantity limited to or lower than a predetermined maximum value at needs so that the actuator can track;

a command value increase and decrease direction determining unit configured to determine an increase and decrease direction of the calculated turning command value of the rear wheel;

a during-steering direction-changing target value change quantity setting unit configured to set a second target value change quantity to the predetermined maximum value have a new changed increase and decrease direction when the command value increases and decrease direction determining unit detects a change in the increase and decrease direction;

an output selecting unit configured to output either of the first target value change quantity inputted from the target speed limiting unit or the second target value change quantity inputted from the during-steering direction-changing target value change quantity setting unit as a target value change quantity; and

a target value setting updating unit configured to add the target value change quantity inputted from the output selecting unit to the last steering angle target value of the rear wheel and outputting a result to the actuator control unit as a new steering angle target value of the rear wheel, wherein

when a tracking error which a difference between the inputted steering angle command value of the rear wheel and the last set steering angle target value of the rear wheel exceeds a predetermined maximum value, the target value speed limiting unit limits the first target value change quantity to the predetermined maximum value, and outputs the tracking error as it is as the first target value change quantity when the tracking error does not exceed the predetermined maximum value;

when the command value increase and decrease direction determining unit detects a change in the decrease and increase direction of the steering angle command value of the rear wheel, the output selecting unit selects and outputs the second target change quantity as the target value change quantity; and

the target value setting updating unit adds the target value change quantity inputted from the output selecting unit to the last steering angle target value of the rear wheel, outputting a result to the actuator control unit as a new steering angle target value of the rear wheel.

4. The rear wheel steering control device as claimed in claim 3, wherein the control unit further comprises:

a during-steering direction-changing neutral detecting unit configured to detect that the steering angle target value reaches a neutral position after the output selecting unit selects and outputs the second target change quantity as the target value change quantity when the command value increase and decrease direction determining unit detects a change in the increase and decrease direction; and

a holding unit configured to replace the steering angle target value change quantity with zero, wherein

the target value setting updating unit causes the holding unit to replace the steering angle target value change quantity with zero, adds it to the last steering angle target value of the rear wheel, and outputs the result as a new steering angle target value to the actuator control unit when the during-steering direction-changing neutral detecting unit detects that the steering angle target value reaches the neutral position after the output selecting unit selects and outputs the second target change quantity as the target value change quantity.

5. A rear wheel steering control device comprising actuators configured to respectively, independently change steering angles of left and right rear wheels installed in a vehicle and a control unit configured to control driving the respective actuators, capable of changing toe angles of the left and right rear wheels independently, wherein:

the control unit comprises;

an actuator control unit configured to independently control the respective actuators;

a toe angle command value calculating unit configured to calculate toe angle command values of the left and right rear wheels on the basis of at least a turning state quantity of a front wheel;

a target value setting updating unit configured to set respective toe angle target values of the left and right rear wheels in accordance with respective toe angle command values of the left and right rear wheels inputted from the toe angle command value calculating unit to perform a target value updating control, and a command value increase and decrease direction determining unit configured to determine increase and decrease directions of the respective inputted toe angle command values of the left and right rear wheels, wherein

the target value setting updating unit performs the target value updating control respectively and independently between the left and right for two sets including;

the toe angle command value of the left rear wheel and the last set toe angle target values of the left rear wheel; and

the toe angle command value of the right rear wheel and the last set toe angle target values of the right rear wheel by;

calculating differences between the toe angle command values of the rear wheels and the last set toe angle target values of the rear wheels as target value change quantities as well as limiting the calculated target value change quantities to or lower than a predetermined maximum values at needs, is added to the last set toe angle target values, and setting the results as new toe angle target value of the left and right rear wheels; and

when the command value increase and decrease direction determining unit detects that either of increase and decrease directions of the toe angle command values of the left and right rear wheels, for the rear wheel of which increase and decrease direction setting changes, setting the toe angle target value change quantity of the rear wheel of which increase and decrease direction setting changes to the predetermined maximum value to have a maximum speed, which is added to the last set toe angle target value of the rear wheels of which increase and decrease direction setting changes.

6. The rear wheel steering control device as claimed in claim 5, wherein after start of the target value updating control in response to that the command value increase and decrease direction determining unit detects that the increase and decrease direction of either of the toe angle command values of the left and right rear wheels changes, when it is detected that the inputted toe angle command value of said rear wheel has not reached a neutral position, at time when the toe angle target value of said rear wheel reaches the neutral position, the target value setting updating unit sets the toe angle target value of said rear wheel to hold the toe angle target value of said rear wheel at the neutral position to perform the target value updating control.

7. A rear wheel steering control device comprising an actuator configured to change a steering angle of a rear wheel installed in a vehicle and a control unit configured to control driving the actuator, capable of changing a steering angle of the rear wheel, wherein:

the control unit comprises;

an actuator control unit configured to control the actuator;

a steering angle command value calculating unit configured to calculate a steering angle command value of the rear wheel on the basis of at least a turning state quantity of a front wheel;

a rear wheel actual steering angle acquiring unit configured to acquire information regarding the actual steering angle of the rear wheel;

a target value setting updating unit configured to set the steering angle target value of the rear wheel inputted into the actuator control unit in accordance with the steering angle command value of the rear wheel inputted from the steering commend value calculating unit to perform a target value updating control; and

a command value increase and decrease direction determining unit configured to determine an increase and decrease direction of the calculated steering angle command value of the rear wheel, wherein the target value setting updating unit performs the updating target value updating control by;

calculating a difference between the steering angle command value of the rear wheel and the actual tuning angle acquired by the rear wheel actual steering angle acquiring unit as a target value change quantity as well as limiting the calculated target value change quantity to or lower than a predetermined maximum value at needs, and adding the result to the actual steering angle value, which is set as a new steering angle target value of the rear wheel, wherein

when detecting that an increase and decrease direction of the toe angle command value of the rear wheel, the command value increase and decrease direction determining unit sets the target value change quantity to a predetermined maximum value to make an action of the actuator at a maximum speed in a direction opposite to that by then, which is added to the actual steering angle.

8. The rear wheel steering control device as claimed in claim 7, wherein after start of the target value updating control in response to that the command value increase and decrease direction determining unit detects that the increase and decrease direction of either of the toe angle command values of the left and right rear wheels changes, when it is detected that the inputted toe angle command value of the rear wheel has not reached a neutral position, at time when the toe angle target value of the rear wheel reaches the neutral position, the target value setting updating unit sets the toe angle target value of the rear wheel to hold the toe angle target value of the rear wheel at the neutral position to perform the target value updating control.

9. A rear wheel steering control device including actuators configured to respectively, independently change steering angles of left and right rear wheels installed in a vehicle and a control unit configured to control driving the actuators, capable of changing toe angles of the left and right rear wheels independently, wherein

the control unit comprises:

an actuator control unit configured to independently control the respective actuators;

a toe angle command value calculating unit configured to control toe angle command values of the left and right rear wheels on the basis of at least a turning state quantity of a front wheel;

an actual toe angle information acquiring unit configured to acquire information regarding actual toe angle of the left and right rear wheels;

a target value setting updating unit configured to set toe angle target values of the left and right rear wheels in accordance with toe angle command values of the left and right rear wheels inputted from the toe angle command value calculating unit to perform a target value updating control, and

a command value increase and decrease direction determining unit configured to determine increase and decrease directions of the respective inputted toe angle command values of the left and right rear wheels, wherein

the target value setting updating unit performs the target value updating control respectively and independently between the left and right, for two sets including;

the toe angle command value of the left rear wheel and the actual toe angle of the left rear wheel by acquired by the actual toe angle information acquiring unit; and

the toe angle command value of the right rear wheel and the toe angle target values of the right rear wheel acquired by the actual toe angle information acquiring unit by;

calculating a difference between the toe angle command values of the rear wheels and the actual toe angle target values of the rear wheels as a target value change quantity as well as limiting the calculated target value change quantity to or lower than a predetermined maximum values at needs which is added to the last set toe angle target values, and setting the results as a new toe angle target value of the left and right rear wheels; and

when the command value increase and decrease direction determining unit detects that either of increase and decrease directions of the toe angle command values of the left and right rear wheels, for said rear wheel of which increase and decrease direction setting changes, setting the toe angle target value change quantity of said rear wheel to the predetermined maximum value to have a maximum speed, and adding it to the actual toe angle of said rear wheels.

10. The rear wheel steering control device as claimed in claim 9, wherein after start of the target value updating control in response to that the command value increase and decrease direction determining unit detects that the increase and decrease direction of either of the toe angle command values of the left and right rear wheels changes, when it is detected that the inputted toe angle command value of the rear wheel has not reached a neutral position, at time when the toe angle target value of the rear wheel reaches the neutral position, the target value setting updating unit sets the toe angle target value of the rear wheel to hold the toe angle target value of the rear wheel at the neutral position to perform the target value updating control.