Thin shell tactile sensing by acoustic wave diffraction patterns

Most of the humanoid robots are covered with curved thin shells. To have a sensitive shell on the robot, normally we need to add an extra layer of electrodes or sensors. In this paper, we realized a tactile shell based on a Lamb wave diffraction method. Surface-contact sensing is calibrated and tested with a finger; the spatial resolution is 17 × 13 on a 100 mm × 75 mm projected-dimension surface. Structure of the tactile shell comprises only four small (25 mm² × 0.5 mm) piezoelectric ceramics transducers bonded to the edges of the shell. The sensing results have good accuracy with response time less than 15 ms, the presented method is able to be used for a humanoid robot´s whole-body tactile sensing.