Apparatus and method for detecting absolute position using difference between detection signals of two detectors
First Claim
1. An apparatus for detecting the absolute rotational position of a steering wheel, wherein the steering wheel is coupled to a power steering apparatus, and the power steering apparatus has a motor, which generates an assisting force to reduce the steering force of the steering wheel, and wherein the motor is controlled in accordance with the steering torque of the steering wheel and the rotational angle of the motor, the detecting apparatus comprising:
- a first detector, which generates a periodic first detection signal in accordance with rotation of the steering wheel, wherein the first detection signal is used for detecting the steering torque of the steering wheel;
a second detector, which generates a periodic second detection signal in accordance with rotation of the motor, wherein the second detection signal is used for detecting the rotational angle of the motor, wherein the cycle of the second detection signal differs from the cycle of the first detection signal, and wherein a level difference, which is the difference between the level of the first detection signal and the level of the second detection signal, varies in accordance with rotation of the steering wheel; and
a computer, wherein the computer in advance stores characteristic information regarding the variation of the level difference, which varies in accordance with rotation of the steering wheel, and wherein the computer calculates the absolute rotational position of the steering wheel based on the current level difference and the characteristic information.
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Accused Products
Abstract
A power steering apparatus includes a motor, a torque sensor, and a motor resolver. The motor generates an assisting force to reduce the steering force of the steering wheel. The torque sensor detects the steering torque of the steering wheel. The motor resolver detects the rotational angle of the motor. An electronic control unit (ECU) detects the absolute position of the steering wheel based on a detection signal Rt sent from a second resolver of the torque sensor and a detection signal Rm sent from a motor resolver. As a result, the cost is reduced and the absolute position of the steering wheel is accurately detected.
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Citations
8 Claims
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1. An apparatus for detecting the absolute rotational position of a steering wheel, wherein the steering wheel is coupled to a power steering apparatus, and the power steering apparatus has a motor, which generates an assisting force to reduce the steering force of the steering wheel, and wherein the motor is controlled in accordance with the steering torque of the steering wheel and the rotational angle of the motor, the detecting apparatus comprising:
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a first detector, which generates a periodic first detection signal in accordance with rotation of the steering wheel, wherein the first detection signal is used for detecting the steering torque of the steering wheel;
a second detector, which generates a periodic second detection signal in accordance with rotation of the motor, wherein the second detection signal is used for detecting the rotational angle of the motor, wherein the cycle of the second detection signal differs from the cycle of the first detection signal, and wherein a level difference, which is the difference between the level of the first detection signal and the level of the second detection signal, varies in accordance with rotation of the steering wheel; and
a computer, wherein the computer in advance stores characteristic information regarding the variation of the level difference, which varies in accordance with rotation of the steering wheel, and wherein the computer calculates the absolute rotational position of the steering wheel based on the current level difference and the characteristic information. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for detecting the absolute rotational position of a steering wheel, wherein the steering wheel is coupled to a power steering apparatus, and the power steering apparatus has a motor, which generates an assisting force to reduce the steering force of the steering wheel, wherein the motor is controlled in accordance with the steering torque of the steering wheel and the rotational angle of the motor, the method comprising:
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generating a periodic first detection signal in accordance with rotation of the steering wheel, wherein the first detection signal is used for detecting the steering torque of the steering wheel;
generating a periodic second detection signal in accordance with rotation of the motor, wherein the second detection signal is used for detecting the rotational angle of the motor, wherein the cycle of the second detection signal differs from the cycle of the first detection signal, and wherein a level difference, which is the difference between the level of the first detection signal and the level of the second detection signal, varies in accordance with rotation of the steering wheel; and
computing the absolute rotational position of the steering wheel based on characteristic information regarding the variation of the level difference, which varies in accordance with rotation of the steering wheel, and the current level difference.
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Specification