AN ACCURATE LOW-COST CAPACITIVE ABSOLUTE ANGULAR-POSITION SENSOR WITHA FULL-CIRCLE RANGE

A novel high-performance smart capacitive angular-position sensor with a full-circle measurement range is presented, The sensor is mainly co mposed of three parts: the capacitive sensing element, a signal proces sor and a microcontroller, Using an appropriate algorithm, the effects of the main undesired influences are eliminated or strongly reduced, The measurement range covers the full-circle range (360 degrees). The structure of the sensing element is optimized to reduce the influence of the electric-field-bending effect and the mechanical errors, The si gnal processor has a multicapacitance input and a single period-modula ted output, and includes a nearly linear capacitance/period converter. The microcontroller acquires output data from the processor, calculat es the positions and optionally communicates with the outside digital world. The resolution of the smart capacitive angular-position sensor is 1.5 arcsec, and the nonlinearity is less than +/- 58 arcsec over th e 0-360 degrees range for a measurement time of 140 ms.