Combined capacitive pressure and proximity sensor for using in robotic systems

Abstract

Circuit solution and primary transducer of combined capacitive pressure and proximity sensor are described. Principle of operation of the developed interface circuit is shown; its principal electrical circuitry is explained. Design and structure of a primary capacitive transducer is considered for further use within the combined sensor. The dependence of the output signal from the force, applied to the prototype sensor, is empirically obtained and shows linear pattern in the working range of the sensor from 0 to 2.6 kg, whereas the sensitivity to the applied pressure was 2252 value/kg in output values of ADC. Graphical dependences of output signal are obtained from the distance between the sensor and the things being observed and consisting of different types of stuff. Mean value of interface circuit sensitivity to approaching object is 6.7 value/mm on the decreasing span of the characteristic curve in the range between 0 and 10 mm. The presented sensor can be employed in manipulators to control object grip, as well in feet of humanoid robot for zero moment point calculation and detection of approach to bearing surface.