Vehicle braking system controller/road friction and hill slope tracking system
First Claim
1. A brake pressure 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 braking in response to said feedforward control value to regulate tire skid.
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Accused Products
Abstract
A method and system for controlling a vehicle braking system on slippery surfaces and hills uses estimates of external conditions from vehicle and engine measurements in a feedforward manner to control vehicle brake pressure 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 and method of controlling vehicle braking. The method includes the step of generating a first disturbance value related to the slope of a hill and a second disturbance value related to the coefficient of friction of the road surface. The first and second disturbance values are then summed to generate a feedforward control value for controlling the level of vehicle braking. The system for controlling vehicle braking includes a first disturbance value related to the slope of a hill and a second disturbance value related to the coefficient of friction of the road surface. The first and second disturbance values are summed to generate a feedforward control value for controlling the level of vehicle braking.
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Citations
17 Claims
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1. A brake pressure 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 braking in response to said feedforward control value to regulate tire skid. - View Dependent Claims (2, 3)
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4. A brake pressure 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 brake pressure; summing said feedforward control value and said error values to generate an optimum brake pressure value; and controlling the level of vehicle braking in response to said optimum brake pressure value.
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5. A brake pressure 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 brake pressure 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 brake pressure signal for generating a reference brake pressure 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 disturbance 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 brake pressure 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 brake pressure signal to produce a first sum and applying the first sum to a first gain to generate a brake pressure error value; summing said second feedback signal and said reference wheel spin error signal to produce a second sum and applying the 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 the third sum to a third gain to generate a driven wheel speed error value; summing said brake pressure error value, said wheel spin error value, said driven wheel speed error value, and said first feedforward value to generate an optimum brake pressure value; and controlling the level of vehicle braking in response to said optimum brake pressure value. - View Dependent Claims (6, 7, 8)
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9. A brake pressure 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 brake pressure, to generate a first feedback signal Pb; 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 brake pressure signal Pbr for generating a reference brake pressure 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 brake pressure 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 Pb and said reference vehicle brake pressure signal Pbr to produce a first sum and applying said first sum to a first gain G1 to generate a brake pressure 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 brake pressure error value, said wheel spin error value, said driven wheel speed error value, and said first feedforward value F to generate an optimum brake pressure value BP; and controlling the level of vehicle braking in response to said optimum brake pressure value BP.
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10. A brake pressure 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, 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 braking in response to said feedforward control value. - View Dependent Claims (11, 12)
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13. A brake pressure 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, 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 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 brake pressure; means for summing said feedforward control value and said error values to generate produce an optimum brake pressure value; and means for controlling the level of vehicle braking in response to said optimum brake pressure value.
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14. A brake pressure 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 comprising:
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means for measuring vehicle brake pressure 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 brake pressure signal for generating a reference brake pressure feedforward value; means for determining a reference wheel spin error signal for generating a reference wheel spin feedforward value; means for determining a reference 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 brake pressure 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 brake pressure signal to produce a first sum and applying said first sum to a first gain to generate a brake pressure 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 brake pressure error value, said wheel spin error value, said driven wheel speed error value, and said first feedforward value to generate produce an optimum brake pressure value; and means for controlling the level of vehicle braking in response to said optimum brake pressure value.
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15. A brake pressure control method for a vehicle having an engine, wheels, tires, 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 related to the slope of a hill; means for generating a second disturbance value related tot he coefficient of friction of the road surface; a summer for summing said first and second disturbance values to generate produce an optimum brake pressure value; and a means for controlling the level of vehicle braking in response to said optimum brake pressure value to regulate the vehicle tire skid. - View Dependent Claims (16, 17)
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Specification