Control system for a front and rear wheel steering vehicle
First Claim
1. A control system for a front and rear wheel steering vehicle, comprising:
- steerable front road wheels steerable by a steering wheel via a front wheel steering device;
steerable rear road wheels steerable by a rear wheel steering actuator;
standard yaw rate computing means for determining a standard yaw rate according to operating conditions of said vehicle including a steering angle of said steering wheel;
yaw rate detecting means for detecting an actual yaw rate of said vehicle;
feedback control means for controlling said rear wheel steering actuator according to a deviation of said actual yaw rate from said standard yaw rate; and
cancelling means for cancelling operation of said feedback control means.
1 Assignment
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Accused Products
Abstract
In a control system for a front and rear wheel steering vehicle which steers the rear wheels so as to cancel a deviation of an actual yaw rate from a standard yaw rate which can be computed from the steering input, the vehicle speed and other parameters, there is provided a feature to automatically and manually cancel the yaw rate feedback control. If the actual yaw rate continues to exceed a threshold level for more than a certain time period, the yaw rate feedback is canceled gradually so as not to cause any abrupt change in the handling of the vehicle. Alternatively, if the vehicle operator wishes to operate the vehicle under extreme conditions, he may manually cancel the yaw rate feedback control so as to avoid undesirable interference or conflict between the manual steering effort and the yaw rate feedback control action. Thus, the maneuverability of the vehicle under extreme conditions can be improved without losing the benefits of the yaw rate feedback control.
88 Citations
19 Claims
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1. A control system for a front and rear wheel steering vehicle, comprising:
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steerable front road wheels steerable by a steering wheel via a front wheel steering device; steerable rear road wheels steerable by a rear wheel steering actuator; standard yaw rate computing means for determining a standard yaw rate according to operating conditions of said vehicle including a steering angle of said steering wheel; yaw rate detecting means for detecting an actual yaw rate of said vehicle; feedback control means for controlling said rear wheel steering actuator according to a deviation of said actual yaw rate from said standard yaw rate; and cancelling means for cancelling operation of said feedback control means. - View Dependent Claims (2, 3, 4, 5)
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6. A control system for a front and rear wheel steering vehicle, comprising:
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steerable front road wheels steerable by a steering wheel via a front wheel steering device; steerable rear road wheels steerable by a rear wheel steering actuator; standard yaw rate computing means for determining a standard yaw rate according to operating conditions of said vehicle including a steering angle of said steering wheel; yaw rate detecting means for detecting an actual yaw rate of said vehicle; feedback control means for controlling said rear wheel steering actuator according to a deviation of said actual yaw rate from said standard yaw rate; cancelling means for cancelling operation of said feedback control means; said cancelling means comprising a manual switch; and said cancelling means further comprising means for allowing a cancelling operation by said cancelling means to be effected gradually.
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7. A control system for a front and rear wheel steering vehicle, comprising:
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steerable front road wheels steerable by a steering wheel via a front wheel steering device; steerable rear road wheels steerable by a rear wheel steering actuator; standard yaw rate computing means for determining a standard yaw rate according to operating conditions of said vehicle including a steering angle of said steering wheel; yaw rate detecting means for detecting an actual yaw rate of said vehicle; feedback control means for controlling said rear wheel steering actuator according to a deviation of said actual yaw rate from said standard yaw rate; cancelling means for cancelling operation of said feedback control means; and said cancelling means effects a cancelling operation according to a result of comparison between said deviation of said actual yaw rate from said standard yaw rate and a first threshold level. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A control system for a front and rear wheel steering vehicle, comprising:
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steerable front road wheels steerable by a steering wheel via a front rear wheel steering device; steerable rear road wheels steerable by a rear wheel steering actuator; standard yaw rate computing means for determining a standard yaw rate according to operating conditions of said vehicle including a steering angle of said steering wheel; yaw rate detecting means for detecting an actual yaw rate of said vehicle; feedback control means for controlling said rear wheel steering actuator according to a deviation of said actual yaw rate from said standard yaw rate; cancelling means for cancelling operation of said feedback control means; feedforward means for controlling said rear wheel steering actuator according to an input to said steering wheel; said cancelling means comprising a manual switch; and said cancelling means further comprising means for allowing a cancelling operation by said cancelling means to be effected gradually.
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14. A control system for a front and rear wheel steering vehicle, comprising;
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steerable front road wheels steerable by a steering wheel via a front wheel steering device; steerable rear wheels steerable by a rear wheel actuator; standard yaw rate computing means for determining a standard yaw rate according to operating conditions of said vehicle including a steering angle of said steering wheel; yaw rate detecting means for detecting an actual yaw rate of said vehicle; feedback control means for controlling said rear wheel steering actuator according to a deviation of said actual yaw rate from said standard yaw rate; cancelling means for cancelling operation of said feedback control means; feedforward means for controlling said rear wheels steering actuator according to an input to said steering wheel; and said cancelling means effects a cancelling operation according to a result of comparison between said deviation of said actual yaw rate from said standard yaw rate and a first threshold level. - View Dependent Claims (15, 16, 17, 18, 19)
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Specification