Compensation of periodic sensor errors in electric power steering systems
First Claim
1. An electric power steering system including:
- a steering wheel,an electric assist motor operatively coupled to the steering wheel,an electronic controller operatively coupled to the assist motor,a steering wheel position sensor for providing an output indicative of an angular position of the steering wheel, anda motor position sensor for providing an output indicative of a relative angular position for the motor;
wherein the controller acquires the steering wheel position sensor output at each of a plurality of angular positions of the motor, thereby establishing a set of points defining a curvilinear relationship between the steering wheel sensor output and the motor position sensor output;
the controller sampling the set of points to calculate a straight line which approximates the curvilinear relationship, thereby reducing periodic errors in the steering wheel sensor output.
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Accused Products
Abstract
An electric power steering system includes a steering wheel, an electric assist motor operatively coupled to the steering wheel, and an electronic controller operatively coupled to the assist motor. A steering wheel position sensor provides an output indicative of an angular position of the steering wheel. A motor position sensor provides an output indicative of a relative angular position for the motor. Steering wheel position sensor output is acquired at each of a plurality of angular positions of the motor, thereby establishing a set of points defining a curvilinear relationship between steering wheel sensor output and motor position sensor output. The set of points is sampled to calculate a straight line which approximates the curvilinear relationship, thereby reducing periodic errors in the steering wheel sensor output. The straight line is employed to determine a position offset for the motor position sensor output corresponding to a system zero position. The system zero position is a position for which the vehicle will travel along a linear, substantially straight-ahead path.
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Citations
18 Claims
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1. An electric power steering system including:
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a steering wheel, an electric assist motor operatively coupled to the steering wheel, an electronic controller operatively coupled to the assist motor, a steering wheel position sensor for providing an output indicative of an angular position of the steering wheel, and a motor position sensor for providing an output indicative of a relative angular position for the motor; wherein the controller acquires the steering wheel position sensor output at each of a plurality of angular positions of the motor, thereby establishing a set of points defining a curvilinear relationship between the steering wheel sensor output and the motor position sensor output; the controller sampling the set of points to calculate a straight line which approximates the curvilinear relationship, thereby reducing periodic errors in the steering wheel sensor output. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for controlling an electric power steering system comprising a steering wheel, an electric assist motor operatively coupled to the steering wheel, an electronic controller operatively coupled to the assist motor, a steering wheel position sensor for providing an output indicative of an angular position of the steering wheel, and a motor position sensor for providing an output indicative of a relative angular position for the motor;
- the method including;
acquiring the steering wheel position sensor output at each of a plurality of angular positions of the motor, thereby establishing a set of points defining a curvilinear relationship between the steering wheel sensor output and the motor position sensor output; and sampling the set of points to calculate a straight line which approximates the curvilinear relationship, thereby reducing periodic errors in the steering wheel sensor output. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
- the method including;
Specification