Methods of controlling four-wheel steered vehicles
First Claim
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1. A method for controlling a vehicle, the vehicle comprising a pair of steerable front wheels and a pair of steerable rear wheels, the method comprising:
- detecting a front wheel steering angle of at least one of the steerable front wheels;
detecting a rear wheel steering angle of at least one of the steerable rear wheels;
determining an overall Ackerman angle;
determining an effective rear wheel steering angle value from the rear wheel steering angle and a scaling factor;
determining a double Ackerman geometry steering angle value based upon the overall Ackerman angle and an Ackerman scaling factor;
determining a feed-forward lateral acceleration value based upon the front wheel steering angle, the effective rear wheel steering angle value, and the double Ackerman geometry steering angle value, the feed-forward lateral acceleration value facilitating feed-forward control of the steerable front wheels and the steerable rear wheels; and
controlling operation of the steerable front wheels and the steerable rear wheels in response to the feed-forward lateral acceleration value.
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Abstract
Methods for controlling a vehicle are provided. The vehicle includes a pair of steerable front wheels and a pair of steerable rear wheels. A steering angle of at least one of the steerable rear wheels is detected. A feed-forward lateral acceleration value is determined based upon the detected steering angle and a scaling factor. Operation of the steerable front wheels and the steerable rear wheels is controlled in response to the feed-forward lateral acceleration value.
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Citations
11 Claims
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1. A method for controlling a vehicle, the vehicle comprising a pair of steerable front wheels and a pair of steerable rear wheels, the method comprising:
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detecting a front wheel steering angle of at least one of the steerable front wheels; detecting a rear wheel steering angle of at least one of the steerable rear wheels; determining an overall Ackerman angle; determining an effective rear wheel steering angle value from the rear wheel steering angle and a scaling factor; determining a double Ackerman geometry steering angle value based upon the overall Ackerman angle and an Ackerman scaling factor; determining a feed-forward lateral acceleration value based upon the front wheel steering angle, the effective rear wheel steering angle value, and the double Ackerman geometry steering angle value, the feed-forward lateral acceleration value facilitating feed-forward control of the steerable front wheels and the steerable rear wheels; and controlling operation of the steerable front wheels and the steerable rear wheels in response to the feed-forward lateral acceleration value. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for operating a vehicle, the vehicle comprising a pair of steerable front wheels and a pair of steerable rear wheels, the method comprising:
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detecting a front wheel steering angle of at least one of the steerable front wheels; and detecting a rear wheel steering angle of at least one of the steerable rear wheels; detecting a vehicular yaw rate; detecting a vehicular speed; determining a yaw-based scaling factor based upon the vehicular yaw rate; determining a speed-based scaling factor based upon the vehicular speed; determining an effective rear wheel steering angle value from the rear wheel steering angle, the yaw-based scaling factor, and the speed-based scaling factor; determining an overall Ackerman angle; determining a double Ackerman geometry steering angle value based upon the overall Ackerman angle and an Ackerman scaling factor; if the vehicular speed is above a threshold speed, determining a feed-forward lateral acceleration value based upon the front wheel steering angle and the effective rear wheel steering angle; if the vehicular speed is equal to or below the threshold speed, determining a feed-forward lateral acceleration value based upon the front wheel steering angle, the effective rear wheel steering angle, and the double Ackerman geometry steering angle value; and controlling operation of the steerable front wheels and the steerable rear wheels in response to the feed-forward lateral acceleration value, wherein the feed-forward lateral acceleration value facilitates feed-forward control of the steerable front wheels and the steerable rear wheels. - View Dependent Claims (8, 9, 10, 11)
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Specification