Noncontact impedance sensing

This article discusses noncontact impedance sensing used to measure the mass, viscosity, and stiffness of an environment. The developed sensor is composed of a laser displacement sensor and an air nozzle for the force supply. The key point of the design is that we use a common axis for both force probing and distance sensor so that we can obtain the exact displacement of the environment. We also discuss the appropriateness of the estimated parameters from the viewpoint of sensitivity of response. Experimental results are shown to confirm the effectiveness of the proposed sensor. We also tested the developed sensor on pears to confirm the possibility of measuring their surface impedance. This work was presented in part at the 10th International Symposium on Artificial Life and Robotics, Oita, Japan, February 4–6, 2005