Patent ID: 7562591
Filing Date: 2009-07-21
Classification: B62D,G01D,G01L

Abstract:
1. An apparatus for determining steering angle and steering torque for a steering column, the steering column including a first shaft and a second shaft interconnected by a torsion bar, the apparatus comprising; a first rotational sensor including a first coil assembly and a first coupler element, the first rotational sensor operable to provide a first signal correlated with an angular position of the first shaft, and a signal processing circuit operable to provide a reference signal; and a second rotational sensor including a second coil assembly and a second coupler element, the second rotational sensor operable to provide a second signal correlated with an angular position of the second shaft, wherein the steering angle is determined using a ratiometric signal obtained using the first signal and the reference signal, the steering torque is determined from a twist angle between the angular position of the first shaft and the angular position of the second shaft, the twist angle being determined using the first signal and the second signal, and the reference signal is correlated with an axial displacement of the first coil assembly but otherwise substantially independent of the angular position of the first shaft, the reference signal being used to determine a number of revolutions of the first shaft so as to extend the angular range of the first rotational sensor.