A proprioceptive DE sensor skin for a fish-like continuum robot

The superior swimming ability of fish has encouraged the development of fish-like robots. To fully capture fish swimming kinematics a continuum under-actuated robot can be used, and there are many examples of such robots in the literature. But for realistic fish-like swimming in strong currents such robots will benefit from closed-loop feedback. We demonstrate how this can be achieved, underwater, using a stretchy neoprene sensing skin with embedded, discrete dielectric elastomer stretch sensors. The latest prototype skin, with 8 sensors, 4 on each side, is currently being evaluated on an underactuated tensegrity fish-like robot driven by a stepper motor. Carangiform movement of the body has been characterized using cameras and this data has been compared with a virtual model of the robot that uses sensor input for real-time model kinematic data. Four angles along the body defined the shape. A root mean square error between model and true camera angles of less than 3° was calculated for realistic cangiform motion at 0.5 Hz tail frequency.