Method for estimating a friction coefficient
First Claim
1. A method of estimating a friction coefficient between a driven wheel and a surface comprising:
- receiving sensor readings indicative of a system state;
determining a desired wheel speed;
calculating a desired wheel slip ratio using said sensor readings and said desired wheel speed; and
using a Fourier series to estimate the friction coefficient.
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Abstract
A method and a system for estimating a friction coefficient between a driven wheel and a surface. The method uses a Fourier series to calculate the friction coefficient. More specifically, a desired wheel slip ratio is calculated using received sensor readings related to a system state and a desired wheel speed determined from various system conditions or user inputs. A Fourier series is used to estimate the friction coefficient. The method is generally cycled many times each second to allow for varying road conditions by adjusting the Fourier series coefficients after each cycle. The system generally includes a wheel speed sensor and an accelerometer providing signals to a processor or various modules to perform the above method.
63 Citations
16 Claims
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1. A method of estimating a friction coefficient between a driven wheel and a surface comprising:
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receiving sensor readings indicative of a system state;
determining a desired wheel speed;
calculating a desired wheel slip ratio using said sensor readings and said desired wheel speed; and
using a Fourier series to estimate the friction coefficient. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of estimating a friction coefficient comprising:
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receiving vehicle sensor readings indicative of a vehicle travel state;
estimating a velocity of the vehicle;
determining a desired wheel speed;
calculating a desired wheel slip ratio using said sensor readings and said desired wheel speed; and
estimating the friction coefficient through a Fourier series wherein said Fourier series uses said desired wheel slip ratio. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A system for estimating a friction coefficient between a driven wheel of a vehicle and a surface, said system comprising:
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a wheel speed sensor and an accelerometer each producing a signal; and
a processor communicating with said wheel speed sensor and accelerometer to receive said signals, said processor including a first module estimating a velocity of the vehicle, a second module determining a desired wheel speed, a third module calculating a wheel slip ratio, said third module receiving said sensor readings and said desired wheel speed from said second module, and a sixth module calculating the friction coefficient, said sixth module using a Fourier series in association with said desired wheel slip ratio to calculate the friction coefficient. - View Dependent Claims (15, 16)
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Specification