Friction drive microrobots: Dynamic analysis and performance evaluation

In this paper, we analytically investigate the dynamic modeling of a nonlinear microrobot based on the "friction drive principle". The superposition of a horizontal vibration at the interface between the robot and work floor and an active variation of friction force, obtained by the vertical vibration of the base, makes the robot to move on the substrate. Periodic solutions obtained from the harmonic balance method can predict the contribution of the friction coefficient on the average velocity of the slider. Unlike traditional analytical techniques and in agreement with both numerical simulations and experiments reported in the literature, results show that the maximum average velocity occurs at a phase shift that varies with respect to system\´s configuration parameters. We have shown that the velocity of the device increases linearly with the relative amplitude of vibrations, whereas the step efficiency of motion, as a performance criterion, can be independently controlled by the driving frequency.