3 Axis Capacitive Tactile Sensor and Readout Electronics

A way to determine the force that is applied to an object, for example by a manipulator, consists in the use of capacitive pressure sensors, like the one presented in this article. The major problems when reading capacitive sensors are the parasitic capacitances between the wires that connect the sensing elements to the interface electronics. The present article describes a capacitive tactile sensor that measures the force in the three axis xx, yy, and zz) and its interface electronics, which consists in a technique that reduces substantially the parasitic capacitance effects. The readout electronics basically is constituted by a 40 kHz voltage source and a current to voltage converter that works as an ammeter. Despite some practical limitations in the complete elimination of the parasitic capacitances, caused by the output impedance of the voltage source and the input impedance of the ammeter, the present work demonstrates that the three axis capacitive tactile sensor and its readout circuit are valid concepts to be applied in the robotics field