ELECTRIC POWER STEERING SYSTEM CONTROL METHODS
First Claim
1. A method of estimating velocity of an electric motor implemented in an electric power steering system utilizing a computer, said method comprising the steps of:
- obtaining a first representation of the velocity of the electric motor from a first velocity signal having a first set of characteristics;
obtaining a second representation of the velocity of the electric motor from a second velocity signal having a second set of characteristics different from the first set of characteristics;
computing a rate of change of the velocity of the electric motor based on the first and second representations of the velocity; and
determining the velocity of the electric motor based on the rate of change of the velocity of the electric motor, the first representation of the velocity of the electric motor, and the second representation of the velocity of the electric motor to produce the estimated velocity of the electric motor.
5 Assignments
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Accused Products
Abstract
An electric power steering system of a vehicle includes a controller for controlling an electric motor connected to a steering column or other steering mechanism. The velocity of the motor must be determined to maintain the proper current to the motor. A method of estimating the velocity includes obtaining a first and second velocity signals from one or more sensors monitoring the motor. The first and second signals have different characteristics, e.g., the first signal may have a higher resolution than the second signal. An acceleration (or deceleration) of the velocity of the electric motor is computed based on the different representations of the velocity supplied by the different signals. An estimate of the velocity of the motor is then determined based on the acceleration/deceleration and the different representations of the velocity. The electric current provided to the electric motor is then adjusted based on the estimated velocity to meet the desired motor output (i.e., motor torque and velocity).
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Citations
17 Claims
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1. A method of estimating velocity of an electric motor implemented in an electric power steering system utilizing a computer, said method comprising the steps of:
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obtaining a first representation of the velocity of the electric motor from a first velocity signal having a first set of characteristics; obtaining a second representation of the velocity of the electric motor from a second velocity signal having a second set of characteristics different from the first set of characteristics; computing a rate of change of the velocity of the electric motor based on the first and second representations of the velocity; and determining the velocity of the electric motor based on the rate of change of the velocity of the electric motor, the first representation of the velocity of the electric motor, and the second representation of the velocity of the electric motor to produce the estimated velocity of the electric motor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of controlling electric current provided to an electric motor implemented in an electric power steering system of a vehicle utilizing a computer, said method comprising the steps of:
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determining a desired velocity of the electric motor based at least in part on the speed of the vehicle; obtaining a first representation of the velocity of the electric motor from a first velocity signal having a first set of characteristics; obtaining a second representation of the velocity of the electric motor from a second velocity signal having a second set of characteristics different from the first set of characteristics; computing a rate of change of the velocity of the electric motor based on the first and second representations of the velocity; determining the velocity of the electric motor based on the rate of change of the velocity of the electric motor, the first representation of the velocity of the electric motor, and the second representation of the velocity of the electric motor to produce the estimated velocity of the electric motor; and adjusting the electric current provided to the electric motor based on the estimated velocity of the electric motor and the desired output of the electric motor. - View Dependent Claims (14, 15, 16, 17)
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Specification