Design and characterization of a miniature monolithic piezoelectric hexapod robot

This paper describes the design, construction and performance of a miniature monolithic piezoelectric hexapod robot. Locomotion is achieved by driving the piezoelectric elements at the mid point between the first and second resonance modes to produce an ambulatory motion. The monolithic robot was milled out of a single piece of outwardly poled piezoelectric bimorph using an ultrasonic milling machine. Silver electrodes were evaporated onto the bimorph to isolate the individual piezoelectric elements from each other. The leg end-effectors of the robot were milled from aluminum and a previously described lumped mass model was used to design the end-effectors such that the swinging and lifting resonance modes were closely matched. The finished robot attained an average swinging and lifting resonance frequency of 308 Hz and 323 Hz with a 1 Hz and 3 Hz spread between the legs respectively.