Vehicle traction controller/road friction and hill slope tracking system
First Claim
1. A traction control method for a vehicle having an engine, wheels, an axle, a throttle, and brakes, the vehicle being driven on a road surface having a coefficient of friction and at least one hill slope, the method comprising the steps of:
- generating a first disturbance value related to the slope of the hill;
generating a second disturbance value related to the coefficient of friction of the road surface;
summing said first and second disturbance values to generate a feedforward control value; and
controlling the level of vehicle traction in response to said feedforward control value by controlling the engine and the wheels.
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Accused Products
Abstract
A system and method for controlling vehicle traction uses estimates of external conditions from vehicle and engine measurements in a feedforward manner to control vehicle traction on slippery or changing surfaces and hills to compensate for external disturbances in an optimal manner. The present invention provides a dual feedforward/feedback system for a method of controlling vehicle traction. The method includes the step of generating a first feedforward value related to the slope of a hill and a second feedforward value related to the coefficient of friction of the load surface. The first and second feedforward values are then summed to generate a feedforward control value for controlling the level of vehicle traction. The system for controlling vehicle traction includes a first feedforward value related to the slope of a hill and a second feedforward value related to the coefficient of friction of the road surface. The first and second feedforward values are summed to generate a feedforward control value for controlling the level of vehicle traction.
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Citations
18 Claims
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1. A traction control method for a vehicle having an engine, wheels, an axle, a throttle, and brakes, the vehicle being driven on a road surface having a coefficient of friction and at least one hill slope, the method comprising the steps of:
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generating a first disturbance value related to the slope of the hill; generating a second disturbance value related to the coefficient of friction of the road surface; summing said first and second disturbance values to generate a feedforward control value; and controlling the level of vehicle traction in response to said feedforward control value by controlling the engine and the wheels. - View Dependent Claims (2, 3, 4)
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5. A traction control method for a vehicle having an engine, wheels, an axle, a throttle, and brakes, the vehicle being driven on a road surface having a coefficient of friction and at least one hill slope, the method comprising the steps of:
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generating a first disturbance value related to the slope of a hill; generating a second disturbance value related to the coefficient of friction of the road surface; generating reference feedforward gains; summing said first and second disturbance values and said reference feedforward gains to generate a feedforward control value; generating error values relating to driven wheel speed, wheel spin, and velocity; summing said feedforward control value and said error values to generate an optimum throttle position value; and controlling the level of vehicle traction in response to said optimum position value.
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6. A traction control method for a vehicle having an engine, wheels, an axle, a throttle, and brakes, the vehicle being driven on a road surface having a coefficient of friction and at least one hill slope, the method comprising the steps of:
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measuring vehicle velocity to generate a first feedback signal; measuring wheel spin error of driven wheel to generate a second feedback signal; measuring driven wheel speed to generate a third feedback signal; determining a reference vehicle velocity signal for generating a reference velocity feedforward value; determining a reference wheel spin error signal to generate a reference wheel spin feedforward value; determining a reference driven wheel speed signal to generate a reference driven wheel spin feedforward value; estimating a hill slope of the road surface from a first disturbing signal to generate a first disturbance value; estimating a coefficient of friction of the road surface value from a second disturbance signal to generate a second disturbance value; summing said reference velocity feedforward value, said reference wheel spin feedforward value, said reference driven wheel spin feedforward value, said first disturbance value, and said second disturbance value, to generate a first feedforward value; summing said first feedback signal and said reference vehicle velocity signal to produce a first sum and applying said first sum to a first gain to generate a velocity error value; summing said second feedback signal and said reference wheel spin error signal to produce a second sum and applying said second sum to a second gain to generate a wheel spin error value; summing said third feedback signal and said reference driven wheel speed signal to produce a third sum and applying said third sum to a third gain to generate a driven wheel speed error value; summing said velocity error value, said wheel spin error value, said driven wheel speed error value, and said first feedforward value to generate an optimum throttle position value; and controlling the level of vehicle traction in response to said optimum throttle position value. - View Dependent Claims (7, 8, 9)
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10. A traction control method for a vehicle having an engine, wheels, an axle, a throttle, and brakes, the vehicle being driven on a road surface having a coefficient of friction and at least one hill slope, the method comprising the steps of:
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measuring vehicle velocity to generate a first feedback signal v; measuring wheel spin error of driven wheel to generate a second feedback signal e; measuring driven wheel speed to generate a third feedback signal w; determining a reference vehicle velocity signal vr for generating a reference velocity feedforward value; determining a reference wheel spin error signal er for generating a reference wheel spin feedforward value; determining a reference driven wheel speed signal wr for generating a reference driven wheel spin feedforward value; estimating a hill slope of the road surface signal, Alpha; estimating a coefficient of friction of the road surface signal, Mu; summing said reference velocity feedforward value, said reference wheel spin feedforward value, said reference driven wheel spin feedforward value, said hill slope of the road surface signal, and said coefficient of friction of the road surface signal, to generate a first feedforward value F; summing said first feedback signal v and said reference vehicle velocity signal vr to produce a first sum and applying said first sum to a first gain G1 to generate a velocity error value; summing said second feedback signal e and said reference wheel spin error signal er to produce a second sum and applying said second sum to a second gain G2 to generate a wheel spin error value; summing said third feedback signal w and said reference driven wheel speed signal wr to produce a third sum and applying said third sum to a third gain G3 to generate a driven wheel speed error value; summing said velocity error value, said wheel spin error value, said driven wheel speed error value, and said first feedforward value F to generate an optimum throttle position value TP, and controlling the level of vehicle traction Tv in response to said optimum throttle position value TP.
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11. A system for controlling the traction of a vehicle having an engine, wheels, an axle, a throttle, and brakes, the vehicle being driven on a road surface having a coefficient of friction and at least one hill slope, comprising:
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means for generating a first disturbance value related to the slope of the hill; means for generating a second disturbance value related to the coefficient of friction of the road surface; means for summing said first and second disturbance values to produce a feedforward control value; and means for controlling the level of vehicle traction in response to said feedforward control value. - View Dependent Claims (12, 13, 14)
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15. A system for controlling the traction of a vehicle having an engine, wheels, an axle, a throttle, and brakes, the vehicle being driven on a road surface having a coefficient of friction and at least one hill slope, comprising:
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means for generating a first disturbance value related to the slope of a hill; means for generating a second disturbance value related to the coefficient of friction of the road surface; means for generating reference feedforward gains; means for summing said first and second disturbance values and said reference feedforward gains to generate produce a feedforward control value; means for generating error values relating to driven wheel speed, wheel spin, and velocity; means for summing said feedforward control value and said error values to produce an optimum throttle position value; and means for controlling the level of vehicle traction in response to said optimum throttle position value.
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16. A system for controlling the traction of a vehicle having an engine, wheels, an axle, a throttle, and brakes, the vehicle being driven on a road surface having a coefficient of friction and at least one hill slope, comprising:
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means for measuring vehicle velocity to generate a first feedback signal; means for measuring wheel spin error of driven wheel to generate a second feedback signal; means for measuring driven wheel speed to generate a third feedback signal; means for determining a reference vehicle velocity signal for generating a reference velocity feedforward value; means for determining a reference wheel spin error signal for generating a reference wheel spin feedforward value; means for determining a reference driven wheel speed signal for generating a reference driven wheel spin feedforward value; means for estimating a hill slope of the road surface from a first disturbance signal to generate a first disturbance value; means for estimating a coefficient of friction of the road surface value from a second disturbance signal to generate a second disturbance value; means for summing said reference velocity feedforward value, said reference wheel spin feedforward value, said reference driven wheel spin feedforward value, said first disturbance value, and said second disturbance value, to generate a first feedforward value; means for summing said first feedback signal and said reference vehicle velocity signal to produce a first sum and applying said first sum to a first gain to generate a velocity error value; means for summing said second feedback signal and said reference wheel spin error signal to produce a second sum and applying said second sum to a second gain to generate a wheel spin error value; means for summing said third feedback signal and said reference driven wheel speed signal to produce a third sum and applying said third sum to a third gain to generate a driven wheel speed error value; means for summing said velocity error value, said wheel spin error value, said driven wheel speed error value, and said first feedforward value to produce an optimum throttle position value; and means for controlling the level of vehicle traction in response to said optimum throttle position value.
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17. A traction control system for a vehicle having an engine, wheels, an axle, a throttle, and brakes, the vehicle being driven on a road surface having a coefficient of friction and at least one hill slope, the system comprising:
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means for generating a first disturbance value relates to the slope of a hill; means for generating a second disturbance value related to the coefficient of friction of the road surface; a summer for summing said first and second disturbance values to produce an optimum throttle position value; and a means for controlling the level of vehicle traction in response to said optimum throttle position value to regulate the vehicle traction. - View Dependent Claims (18)
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Specification