Biomimetic flexible/compliant sensors for a soft-body lamprey-like robot

This paper focuses on the development of biomimetic sensory abilities for an undulatory soft-body lamprey-like robot, which has been designed to replicate the locomotion mechanisms of living lamprey in order to address useful applications wherever locomotion in unstructured environments is required. The compliant sensory elements are piezo-resistive and made from compliant material called a quantum tunneling composite by mixing micro/nano carbon black particles into a highly soft silicone rubber matrix. The relationship of the composite strip between piezo-resistivity and mechanical strain is investigated by a universal strain–stress tensiometer through resistivity monitoring. Increasing and decreasing resitivity both appears during elongation and retraction, suggesting that piezo-resistivity in the composite material is governed by both percolation theory and quantum tunneling effects. Dynamic tests on the bench shows that the compliant stretch receptor is able to follow the stimulations under fairly wide frequency ranges, exceeding initial estimations. In addition, the compliant artificial stretch receptor has enough sensitivity to detect the local actuations and the actions generated by neighboring actuators in the segmented robotic structure. Finally, the experiments on biomimetic cilia-based cupula receptor show that a low cost flexible/compliant biomimetic sensor is able to detect medium fluidic speeds ranging from 0.05 m/s to 0.6 m/s.