| 摘要 |
A rotational position sensing arrangement (10) for sensing the rotational position of a rotatable member (12) includes at least one excitation circuit. The excitation circuit has a section which includes an excitation coil (20), and the excitation circuit is operable to energise the section, the energy causing current to flow in the section when the section is not driven, thereby exciting an oscillating electromagnetic field. Means for coupling to the electromagnetic field is provided, comprising a coupling circuit (16) including a coupling coil (22), the oscillation of the electromagnetic field causing the coupling circuit (16) to resonate thereby damping the oscillations of the electromagnetic field. The one or more excitation circuits or the coupling means are associated with the rotatable member (12). By providing such a coupling means damping can be improved. Means for detecting the value of a parameter of the oscillations associated with each of one or more excitations in each of one or more of the excitation coils (20) is provided, the parameter being the number of oscillations for which the amplitude exceeds a predetermined threshold value. Processing means for determining the rotational position of the rotatable member (12) at a particular time from the parameter value is provided. |
