OBJECT IMAGING WITH A PIEZOELECTRIC ROBOTIC TACTILE SENSOR

A two-dimensional, electrically multiplexed robotic tactile sensor was realized by coupling a piezoelectric polyvinylidene fluoride (PVDF) polymer film to a monolithic silicon integrated circuit (IC), The IC incorporates 64 sensor electrodes arranged in a symmetrical 8x8 matrix, Each electrode occupies a 400x400 mu m square area, and they are separated from each other by 300 mu m. A 40-mu m-thick piezoelectric PVDF polymer film was attached to the electrode array with an electrically nonconductive urethane adhesive, The response of the tactile sensor is linear for loads spanning 0.8-135 grams-of-force (gmf) (0.008-1.35 Newtons (N)), The response bandwidth is 25 Hz, the hysteresis level is tolerable; and, for operation in the sensor's linear range, taxel crosstalk is negligible, The historically persistent stability and response reproducibility limitation associated with piezoelectric-based tactile sensors has been solved by implementing a novel pre-charge voltage bias technique to initialize the pre- and post-load sensor responses, A rudimentary tactile object image measurement procedure for applied loads has been devised to recognize the silhouette of a sharp edge, square, trapezoid, isosceles triangle, circle, toroid, slotted screw, and cross-slotted screw. [92]