Stretchable Multi-modal Sensor using Capacitive Cloth for Soft Mobile Robot Passing through Gap

A challenging issue for soft robots is developing soft sensors that measure such non-contact information as the distance between a robot and obstacles as well as contact information such as stretch length by external force. Another issue is to adopt the sensor to the mobile robot to measure topography of pathway. We adopt capacitive cloth, which contains conductive and insulation layers, and measure not only such contact information as the robot's deformation but also such non-contact information as the distance between the cloth and objects. Because the cloth cannot stretch though it deforms, it is processed by the Kirigami structure and embedded into a silicone plate. This paper shows the cloth's basic specifications by measuring the relationship between the capacitance and the stretch length that corresponds to the contact information and the one and distance that corresponds to the non-contact information. The cloth is also embedded in a soft mobile robot that passes through a narrow gap while making contact with it. The pathway's shape is estimated by observing the profile of the cloth's capacitance by using contact information. From the results of the first experiment, which measured the stretch length, we observed a strong correlation between the stretch length and the capacitance. In the second experiment on non-contact information and distance, the capacitance greatly changed when the conductive material was close to cloth, although less-conductive material did not greatly affect the capacitance. In the last experiment in which we embedded the cloth into the soft robot, the gap's height and length of the pathway were detected by observing the profile of the cloth's capacitance. These results suggest that capacitive cloth has multi-modal sensing ability, including both conventional contact and novel non-contact information.

Automated summary

This study introduced a capacitive cloth sensor that can measure the distance between soft robots and obstacles as well as the topography of pathways. The sensor is able to measure both contact information and non-contact information, showing a strong correlation between capacitance and stretch length in the first experiment. Additionally, the cloth's multi-modal sensing ability was demonstrated in various experiments.