Dual-axis Hybrid Tactile Sensor

Robotic grasping requires not only force and touch sensors but also flexibility of such sensors because most of the sensors are attached to the finger tip. Many studies are underway in such sensors using polymer because polymer is flexible and affordable. Polydimethylsiloxane (PDMS) is one of widely used substances because it is very stable physically and chemically. The principle of the capacitive force sensor using polymer is as follows; capacitance values will be changed by changes in the thickness of the dielectric elastomer under normal force or changes in the overlapping area of electrodes under shear force. The force and moment are measured by such changes. Conventional one-axis capacitive type force sensors measure normal or tangential force from one pair of electrodes. The increased number of electrodes can be used for multi-axis force sensors at the cost of the size of the sensor and resolution of the sensor. In this paper, we propose a dual-axis capacitive and resistive hybrid-type force sensor using dielectric elastomer with only one pair of electrodes. The electrodes are made with thermal evaporator. With only one pair of electrodes, the normal force is measured from the change of capacitance and resistance values and the shear force is measured from the change of only capacitance values. Experimental results verify the effectiveness of the proposed dual-axis hybrid type force sensor.