Method and apparatus for electromagnetically resolving the angle of a rotatable shaft
First Claim
1. A method for determining a shaft angle using signals produced by sine and cosine resolver windings associated with the shaft comprising:
- stimulating the sine and cosine windings using a resolver drive signal;
sampling the sine winding signal and cosine winding signal at a frequency that is greater than the resolver drive signal frequency;
applying a Fourier transform to the sine winding signal sample and to the cosine winding signal sample;
determining the polarity of the drive signal at the time of each winding sample;
applying the drive signal polarity to the Fourier transforms of the winding signal samples to obtain Fourier transform samples with polarity;
dividing the Fourier transform samples with polarity one into the other to obtain a trigonometric function of the shaft angle; and
calculating the shaft angle from the trigonometric function.
2 Assignments
0 Petitions
Accused Products
Abstract
A method and apparatus for determining the angle of a shaft (16) of an electromagnetic resolver which has resolver windings (10, 12) is disclosed. The sine and cosine resolver winding signals (30, 32) are sampled at a frequency significantly greater than the resolver drive signal. A fast fourier transform (38, 40) is then applied to the winding signals. The polarity of the drive signal (42) is applied to the FFT output (44, 46) and the results are divided one into the other (52) to obtain the arctangent of the shaft angle (56). Using a multiplexer (22) the apparatus can be coupled to a large number of different electromagnetic resolvers.
34 Citations
13 Claims
-
1. A method for determining a shaft angle using signals produced by sine and cosine resolver windings associated with the shaft comprising:
-
stimulating the sine and cosine windings using a resolver drive signal; sampling the sine winding signal and cosine winding signal at a frequency that is greater than the resolver drive signal frequency; applying a Fourier transform to the sine winding signal sample and to the cosine winding signal sample; determining the polarity of the drive signal at the time of each winding sample; applying the drive signal polarity to the Fourier transforms of the winding signal samples to obtain Fourier transform samples with polarity; dividing the Fourier transform samples with polarity one into the other to obtain a trigonometric function of the shaft angle; and calculating the shaft angle from the trigonometric function. - View Dependent Claims (2, 3, 4, 5)
-
-
6. A resolver for determining the angle of a rotable shaft comprising:
-
a sine winding and a cosine winding associated with the shaft; a resolver primary winding associated with the shaft, one of either the primary winding or the sine and cosine windings being connected to the shaft so that the relative positions of the windings are indicative of the shaft angle; a resolver winding drive circuit for generating a drive signal and supplying it to the primary winding to stimulate winding signals in the sine and cosine windings that are indicative of the shaft angle; a sampler for sampling the sine and cosine winding signals; means for determining the Fourier transform of the winding signal samples; means for determining the polarity of the drive circuit drive signal for each sample and applying that polarity to the Fourier transforms of the winding signal samples; a divider for dividing the Fourier transforms with applied polarity one into the other to obtain a trigonometric function of the shaft angle; and means for calculating the shaft angle from the trigonometric function. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13)
-
Specification