A Linear Variable Differential Capacitive Transducer for Sensing Planar Angles

A linear variable differential capacitive transducer for the measurement of planar angles from 0deg to 360deg is presented in this paper. The sensor part of the transducer consists of parallel plates of standard and easy to fabricate shapes and the signal conditioning electronics is made of a couple of simple relaxation oscillators. The output of the transducer is dictated only by a couple of dc reference voltages and hence high accuracy and linearity over the entire 0deg to 360deg are obtained easily by the use of precision dc reference voltages. Error analysis indicates that the sensitivity of the transducer for parameter variation is minimal. Test results obtained from a prototype indicated that the worst-case error was less than 0.1 %