Method for Controlling the Orientation of the Rear Wheels of a Vehicle
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Abstract
A method for controlling orientation of rear wheels of a vehicle, by a computerized control system, including a module for calculation of a deflection angle for the rear wheels as a function of a deflection angle of the front wheels. In the method, when the front wheels are oriented for a period of time such that the vehicle follows a curved trajectory with an inner side and an outer side, the rear deflection angle, as determined by the calculation module, is corrected and limited to a maximum value calculated instantaneously such that a rear corner then follows a trajectory remaining within the curved trajectory previously followed by a front corner and, furthermore, at a tangent to the same.
21 Citations
24 Claims
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1-12. -12. (canceled)
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13. A method for controlling orientation of rear wheels of a vehicle having a body of longitudinal axis and borne by orientable wheels on each side of the axis, the orientable wheels being at least one steered front wheel and at least one rear wheel, respectively, orientation of the front wheels being controlled by a driver so as to follow a path and the orientation of the rear wheels being under control of a computerized control system including a module for calculating a steering angle of the rear wheels as a function of the steering angle of the front wheels, the body of the vehicle having a substantially rectangular shape with two front corners and two rear corners overhanging in front of the front wheels and behind the rear wheels, respectively, in which method:
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when the front wheels have been orientated, for a period of time, such that the vehicle follows a path that has an inside and an outside, the computerized control system determines, at successive intervals of time each corresponding to a basic position, an imaginary path equivalent to the path followed earlier by the front corner over a length corresponding to the length of the vehicle, behind a relevant basic position of the front corner and calculates, at each instant, a corrected rear steering angle such that the resulting path for the rear corner, taking into consideration the length of the vehicle, remains inside the imaginary path, wherein, to determine the imaginary path behind a basic position, the computerized control system measures, at each instant, a collection of parameters representative of displacement, including at least the current longitudinal speed of the vehicle, with a positive sign forwards, and the angles of orientation of the front wheels and of the rear wheels, with respect to the longitudinal axis of the vehicle, with a positive sign in the clockwise direction and, as the vehicle moves, divides the path followed by the front corner into a series of elementary displacements between a series of basic positions and, as the front corner enters a basic position, defines an orthonormal frame of reference for the vehicle having, as its origin, the center of gravity and two perpendicular axes, the axes being an abscissa axis corresponding to the longitudinal axis of the vehicle and an ordinates axis, and wherein, based on mean values of representative parameters stored in a memory in respect of the basic position, the control system formulates an equation, in the frame of reference of the vehicle, of an equivalent path of the front corner and, by taking it that, during a next elementary displacement, the front corner follows a forward continuation of the imaginary path and that the front steering angle is maintained, determines the predicted path of the rear corner and corrects the rear steering angle so that this predicted path of the rear corner remains inside and is at most tangential to the equivalent path of the front corner lagging behind the latter by a distance corresponding to the length of the vehicle. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification