An Annular Planar-Capacitive Tilt Sensor With a 360° Measurement Range

A planar-capacitive tilt sensor with concentric annular electrodes is proposed for further expansion of inclination measurement range. Using dielectric liquid as a sensing pendulum, the proposed sensor can measure the inclination angle of an object with respect to gravity, such as a crane boom or a robot manipulator. The capacitance values of four segmented annular planar capacitors in sensor head vary with the rotation of the object. Such measurement mechanism remains effective even with a 360° rotation. In our lab, a tilt-sensor prototype was assembled with optimized sensor head and suitable dielectric liquid and its performance was evaluated on a tilted plane. Experimental results show that a full measurement range of 360° was achieved with an accuracy of 0.4° and a resolution better than 0.1°. Moreover, the proposed tilt sensor is easy to fabricate, and its components are available at a low cost.