A novel rail-type piezoelectric robot for Tokamak maintenance operation

A novel rail-type piezoelectric robot is proposed in this study, presenting the potential application for the maintenance operation of the Tokamak vacuum chamber. Four straight beams adhered with piezoelectric ceramics form a rectangular frame of the robot. Two-phase bending vibrations with a spatial phase difference of 90° are excited in the two shorter beams respectively, leading tomicroscopic elliptical motions at the driving feet. Therefore, the robot can move in the straight rail utilizing friction. Finite element analysis was carried out to verify the operation principle and to optimize the dimensions of the robot. A prototype of the robot with a mass of 83.8 g was fabricated, assembled and tested. With a driving voltage of 300 V
_pp
, the maximum velocities in two directions are 92.4 mm/s and 196.5 mm/s respectively. With an excitation voltage of 400 V
_pp
, the maximum load capacity of the prototype is 200 g.