Rear wheel steering control system for vehicle

A rear wheel steering control system for a vehicle comprising:

• first means for monitoring a steered angle of front wheels for deriving a signal indicative thereof;
• second means including sensors for monitoring rotational speeds of wheels and determining a difference in rotational speeds between the front and rear wheels and the vehicle speed and for deriving signals indicative thereof;
• third means for determining a rear wheel steering angle having a preselected relation to the steered angle of the front wheels and the vehicle speed for deriving a signal indicative thereof;
• fourth means responsive to generation of a difference in rotational speeds between the front and rear wheels for deriving a correction value for the rear wheel steering angle determined by said third means in a preselected relation to a degree of difference in rotational speeds between the front and rear wheels and deriving a rear wheel target steering angle;
• fifth means for controlling traction of driven wheels of the vehicle so as to compensate for the difference in rotational speeds between the front and rear wheels when a value representing the difference in rotational speeds between the front and rear wheels is greater than a reference value;
• sixth means for holding the correction value to zero during traction control of driven wheels by said fifth means;
• and
• seventh means for controlling an actual steering angle of the rear wheel according to the rear wheel target steering angle.

A combination of a rear wheel steering control system and a traction control system for a vehicle comprising:

• first means for monitoring a steered angle of front wheels to provide a signal indicative thereof;
• second means including sensors for monitoring rotational speeds of wheels for determining a difference in rotational speeds between the front and rear wheels and the vehicle speed and for deriving signals indicative thereof;
• third means for determining a rear wheel steering angle based on the steered angle of the front wheels and the vehicle speed for deriving a signal indicative thereof;
• fourth means for compensating the rear wheel steering angle determined by said third means based on the difference in rotational speeds between the front and rear wheels for deriving a rear wheel target steering angle;
• fifth means responsive to the difference in rotational speeds between the front and rear wheels being greater than a preselected reference value for restricting the compensating operation of said fourth means and driving the rear wheel steering angle as determined by said third means as the rear wheel target steering angle;
• and
• sixth means for controlling an actual steering angle of the rear wheel according to the rear wheel target steering angle.

A method of controlling rear wheel steering of a vehicle comprising:

• monitoring a steered angle of front wheels of the vehicle;
• monitoring rotational speeds of front and rear wheels of the vehicle;
• responding to the monitored speeds to determine (a) the difference in rotational speeds of the front and rear wheels and (b) speed of the vehicle;
• determining rear wheel steering angle based on the steered angle of the front wheels and the vehicle speed;
• compensating the rear wheel steering angle determined during the previous step based on the difference in rotational speeds between the front and rear wheels to derive a rear wheel target steering angle;
• responding to the difference in rotational speeds between the front and rear wheels being greater than a preselected reference value to control traction of driven wheels of the vehicle so as to compensate for the difference in rotational speeds between the front and rear wheels;
• responding to the traction control to restrict said compensating operation and derive the rear wheel target steering angle as determined by the steered angle of the front wheels and the vehicle speed;
• and
• controlling the actual steering angle of the rear wheel according to the rear wheel target steering angle.

A rear wheel steering control system for a vehicle comprising:

• first means for monitoring a steered angle of front wheels of the vehicle and deriving a signal indicative thereof;
• sensors for monitoring rotational speeds of wheels of the vehicle and deriving signals indicative thereof;
• means for controlling an actual steering angle of the rear wheels according to a rear wheel target steering angle;
• and
• means responsive to all said signals for activating said control means;
• said activating means:
• (a) determining a difference in rotational speeds between the front and rear wheels and speed of the vehicle to derive signals indicative thereof;
• (b) determining a rear wheel steering angle based on the steered angle of the front wheels and the vehicle speed for deriving a signal indicative thereof;
• (c) compensating the determined rear wheel steering angle based on the difference in rotational speeds between the front and rear wheels for deriving said rear wheel target steering angle;
• (d) responding to the difference in rotational speeds between the front and rear wheels being greater than a preselected reference value for controlling traction of driven wheels of the vehicle so as to compensate for the difference in rotational speeds between the front and rear wheels;
• and (e) responding to the traction control operation to restrict said compensating operation and derive the rear wheel steering angle as determined by the steered angle of the front wheels and the vehicle speed.

A method of controlling rear wheel steering of a vehicle comprising:

• monitoring a steered angle of front wheels of the vehicle;
• monitoring rotational speeds of front and rear wheels of the vehicle;
• responding to the monitored speeds to determine (a) the difference in rotational speeds of the front and rear wheels and (b) speed of the vehicle;
• determining a rear wheel steering angle as a preselected relation to the steered angle of the front wheels and the vehicle speed;
• responding to the difference in rotational speeds between the front and rear wheels to derive a correction value for the rear wheel steering angle determined in response to the steered angle of the front wheels and the vehicle speed in a preselected relation to a degree of difference in rotational speed between the front and rear wheels to derive a rear wheel target steering angle;
• controlling traction of driven wheels of the vehicle so as to compensate for the difference in rotational speeds between the front and rear wheels when a value representing the difference in rotational speeds between the front and rear wheels is greater than a reference value;
• holding the correction value to zero during the traction control step of the driven wheels;
• and
• controlling the actual steering angle of the rear wheels according to the rear wheel target steering angle.

A method of controlling rear wheel steering of a vehicle comprising:

• monitoring a steered angle of front wheels of the vehicle;
• monitoring rotational speeds of front and rear wheels of the vehicle;
• responding to the monitored speeds to determine (a) the difference in rotational speeds of the front and rear wheels and (b) speed of the vehicle;
• determining rear wheel steering angle based on the steered angle of the front wheels and the vehicle speed;
• compensating the rear wheel steering angle determined during the previous step based on the difference in rotational speeds between the front and rear wheels to derive a rear wheel target steering angle;
• responding to the difference in rotational speeds between the front and rear wheels being greater than a preselected reference value to restrict the compensating operation and derive the rear wheel target steering angle as determined by the steered angle of the front wheels and the vehicle speed;
• and
• controlling the actual steering angle of the rear wheels according to the derived rear wheel target steering angle.

A rear wheel steering control system for a vehicle comprising:

• first means for monitoring a steered angle of front wheels of the vehicle and deriving a signal indicative thereof;
• sensors for monitoring rotational speeds of wheels of the vehicle and deriving signals indicative thereof;
• means for controlling an actual steering angle of the rear wheels according to a rear wheel target steering angle;
• control means for traction of driven wheels of the vehicle;
• and
• means responsive to all said signals for activating said control means;
• said activating means:
• (a) determining the difference in rotational speeds between the front and rear wheels and the speed of the vehicle to derive signals indicative thereof;
• (b) determining a rear wheel steering angle based on a preselected relation of the steered angle of the front wheels and the vehicle speed to provide a signal indicative thereof;
• (c) responding to the difference in rotational speeds between the front and rear wheels for deriving a correction value for the rear wheel steering angle determined by said preselected relation to the steered angle of the front wheels and the vehicle speed in a preselected relation to a degree of difference in rotational speeds between the front and rear wheels and deriving said rear wheel target steering angle;
• (d) controlling traction of the driven wheels so as to compensate for the difference in rotational speeds between the front and rear wheels when a value representing the difference in rotational speeds between the front and rear wheels is greater than a reference value;
• and (3) holding the correction value to zero during the traction control operation for the driven wheels.

A combination rear wheel steering control systems and traction control system for a vehicle comprising:

• first means for monitoring a steered angle of front wheels of the vehicle and deriving a signal indicative thereof;
• sensors for monitoring rotational speeds of wheels of the vehicle and deriving signals indicative thereof;
• means for controlling an actual steering angle of the rear wheels according to a rear wheel target steering angle;
• means for controlling traction of the vehicle;
• means responsive to all said signals for activating said control means;
• said activating means:
• (a) determining the difference in rotational speeds between the front and rear wheels and the speed of the vehicle to derive signals indicative thereof;
• (b) determining a rear wheel steering angle based on the steered angle of the front wheels and the vehicle speed for deriving a signal indicative thereof;
• (c) compensating the determined rear wheel steering angle based on the difference in rotational speeds between the front and rear wheels to provide said rear wheel target steering angle;
• (d) responding to the difference in rotational speeds between the front and rear wheels being greater than a preselected reference value for restricting the compensating operation and deriving the rear wheel steering angle as determined by the steered angle of the front wheels and the vehicle speed.