Step Displacement Improving Method of Inertial Actuated Piezoelectric Robot Based on Diagonal Deformation Trajectory

For the miniature piezoelectric robots operated by inertial driving method, the step displacements were limited by the deformations of the inertial units. Thus, a diagonal inertial driving method (DIDM) was proposed in this work to increase the step displacement. The prominent feature of DIDM was that the inertial force was in diagonal direction by using the designed piezoleg with square cross section. The vertical component of the inertial force reduced the friction force and even made the robot jump to achieve a larger step displacement. The experimental results indicated that the proposed DIDM increased the step displacement successfully. The increase effect was optimal when the vertical component of the inertial force was equal to the horizontal one, and the realized step displacement was as high as 156% to the deformation of the inertial unit in motion direction. Moreover, the force and displacement responses of the driving foot in vertical direction were measured, which indicated that the robot realized jumping action to increase the step displacement under DIDM, and the maximum speed realized by DIDM was 2.3 times of that achieved by the traditional inertial driving method. We believe that the proposed DIDM can broaden the solutions of improving the performances of the inertial miniature piezoelectric robots.