Origami-inspired triboelectric sensor (TES) for shape detection of underwater thruster

Abstract The shape change of the thruster can reflect its motion state, and motion control of the thruster can be carried out more effectively by monitoring its motion state. The unique structure of the origami thruster increases the difficulty of sensor configuration, which significantly limits the application of origami structures (ORSs) in the thruster field. To solve the above problems, we propose a triboelectric sensor (TES) based on a triboelectric nanogenerator, which can be perfectly matched with an ORS and used to monitor the shape of an underwater thruster. The TES proposed can sense the folding angle of the structural unit of the origami thruster and then monitor its shape. The effects of different friction layer materials, different friction layer thicknesses, and multiple pairs of friction subs in series/parallel were analyzed on TES output characteristics. A scheme with thin copper sheets as electrodes, the polyethylene terephthalate resin as dielectric layers, and four pairs of friction pairs connected in parallel were selected for sensor performance testing. Finally, the origami thruster and TES are assembled for underwater testing. The shape of the origami thruster was monitored using the TES. The dihedral angle that TES can detect ranges from 22.5° to 63.5°, corresponding to the radius variation of the thruster ranging to 44.4%. The maximum error between the output result and the measured value was 4.19%, which proves that TES has a good detection effect on the shape change of the thruster and has a broad application prospect in robot motion monitoring.