Method for controlling an electric power assist steering system with low hysteresis and torque ripple
First Claim
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1. A method for controlling an electric power assist steering system comprising:
- sensing torque in a steering shaft at a point along said steering shaft between a hand wheel and a mechanical connection to an electric motor, said sensing comprising sensing a magnetic field direction and intensity;
detecting said magnetic field using a magnetic field vector sensor disposed coaxially over said steering shaft;
maintaining said magnetic field vector sensor coaxially over said steering shaft by supporting said magnetic field vector sensor on said steering shaft using a bearing; and
, prohibiting said magnetic field vector sensor from rotating with said steering shaft by mechanically engaging said magnetic field vector sensor with a steering shaft housing.
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Abstract
An electric power assist steering system is controlled by sensing torque in a steering shaft at a point along said steering shaft between a hand wheel and a mechanical connection to an electric motor, wherein the sensing includes sensing a magnetic field direction and intensity.
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Citations
16 Claims
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1. A method for controlling an electric power assist steering system comprising:
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sensing torque in a steering shaft at a point along said steering shaft between a hand wheel and a mechanical connection to an electric motor, said sensing comprising sensing a magnetic field direction and intensity;
detecting said magnetic field using a magnetic field vector sensor disposed coaxially over said steering shaft;
maintaining said magnetic field vector sensor coaxially over said steering shaft by supporting said magnetic field vector sensor on said steering shaft using a bearing; and
,prohibiting said magnetic field vector sensor from rotating with said steering shaft by mechanically engaging said magnetic field vector sensor with a steering shaft housing. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of controlling an electric power assist steering system with reduced hysteresis and torque ripple, the method comprising:
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sensing torque in a steering shaft at a point along said steering shaft between a hand wheel and a mechanical connection to an electric motor, said sensing comprising sensing a magnetic field direction and intensity without use of a torsion bar, thereby reducing said hysteresis and said torque ripple in said system;
detecting said magnetic field using a magnetic field vector sensor disposed coaxially over said steering shaft;
maintaining said magnetic field vector sensor coaxially over said steering shaft by supporting said magnetic field vector sensor on said steering shaft using a bearing; and
,prohibiting said magnetic field vector sensor from rotating with said steering shaft by mechanically engaging said magnetic field vector sensor with a steering shaft housing. - View Dependent Claims (8, 9, 10)
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11. A method for controlling an electric power assist steering system comprising:
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sensing torque in a steering shaft at a point along said steering shaft between a hand wheel and a mechanical connection to a motor, said sensing comprising sensing a magnetic field direction and intensity with a non-compliant torque sensor;
providing a controller in operable communication with the motor;
mechanically engaging said sensor with a steering shaft housing;
connecting said sensor directly to said controller through a connection pathway in said steering shaft housing;
receiving a signal from the non-compliant torque sensor in the controller; and
,sending a signal from the controller to the motor in response to the signal from the non-compliant torque sensor received in the controller. - View Dependent Claims (12, 13, 14, 15, 16)
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Specification