| 摘要 |
A parameter of one or more oscillating components in a noisy input signal is estimated by sampling the input signal S202, recursively generating a Z-transform component S204, transforming the Z-transform component to give frequency, phase or amplitude of the Z-transform component S206 and using this to give the parameter of an oscillating component in the input signal S208. Transforming the Z-transform component may involve finding an elliptical locus in the complex plane, aligning the minor and major axes of the ellipse with the real and imaginary axes and mapping the ellipse to a circular locus. The input signal may be the current in a drive coil of a motor and first and second oscillating components in the input may be the drive current and a current induced by back EMF. A drive voltage may be controlled based on the parameters estimated for the second oscillating component. |
