The application of the capacitor's physics to optimize capacitive angular-position sensors

The distributions of the potential and charge density in a capacitive angular-position sensor with three electrode disks in an axis-symmetrical configuration have been found by creating a suitable physical model and solving Laplace's equation. The influences of geometrical parameters on the nonlinearity, which originates from the electric-field-bending effect, are discussed in detail for a capacitive angular-position sensor. The approximately analytical results are verified by a numerical analysis and are found to be very useful to predict the influences of geometrical nonidealities. The calculations are experimentally verified by using a novel, absolute angular-position sensor with a nonlinearity of less than /spl plusmn/17" and /spl plusmn/50" over measurement ranges of 15/spl deg/ and 90/spl deg/, respectively.