Having previously proposed a hybrid tactile sensor system consisting of a Carbon Micro-Coil (CMC) touch sensor and a force sensor, the authors have been developing a method of measuring deformation of micrometer order, force variance of 10 gram order, and compression force when an object touches a sensor element and moves slightly. In this paper, to measure the force variance for deformation of several micrometers using the CMC touch sensor, the force characteristics of the CMC touch sensor are investigated. The CMC sensor element is made of silicon rubber containing CMCs several micrometers in diameter. It is considered that the sensor element constitutes an LCR circuit, and the CMC touch sensor, deformed mechanically, produces signals due to the modification of the circuit. In the experiment detailed in this paper, to clarify the characteristics of the CMC sensor with respect to the parameters of force and deformation, the outputs of the CMC sensor and the force sensor for deformation in the range of 1 to 9 µm are sampled. As a result, it is found that the force characteristics of the CMC touch sensor are almost linear in terms of force variance within the range of 0 to 1 N, regardless of a compression force of less than 3 N. Finally, to evaluate the performance of the sensor system, force variance for a slight movement of an object touching the sensor element is estimated in an experiment.
