Robust velocity control for an A-shaped micro-robot with stick-slip locomotion

Abstract

In this paper, the problem of velocity control of a micro-robot's locomotion with nanometric resolution has been investigated. A sliding, A-shaped micro-robot, used in precision positioning applications is analyzed. This micro-robot is actuated by means of a piezoelectric stack actuator in order to produce translational and periodic motion. A dynamic model of the robot is proposed assuming linear behavior for the piezoelectric stack and Coulomb friction model. Then, in order to control the velocity of micro-robot, first a robust sliding mode control is used so that the relative angle between the legs in the micro-robot tracks a periodic reference signal. The velocity tracking for the micro-robot is achieved using an amplitude modulation strategy by adapting the amplitude of this reference signal. Velocity control of locomotion is assumed to be in the presence of a non-separation constraint (between the legs and the substrate) and friction uncertainties. Also, a state observer is designed to estimate the rate of change of the relative angle between the legs of the micro-robot, which is needed in the velocity control algorithm. Finally, simulation results are presented which illustrate the effectiveness of the proposed control strategy.

H∞ control of integrated rollover prevention system based on improved lateral load transfer rate

“…In order to reject these negative influences to the control effect and guarantee the robust stability of system, the H ∞ robust system is designed in this paper. Also, it has been noted (Moradian and Vossoughi, 2015; Van and Kang, 2015; Yim et al, 2010; Zhao et al, 2015; Zhao and Qin, 2017) that H ∞ norm is a measure index for transfer function gain. In brief, it is a kind of magnification time from system input to output.…”

Developments and Challenges of Miniature Piezoelectric Robots: A Review

“…[39][40][41][42] Among them, the piezoelectric actuating elements exhibit many impressive advantages, such as compact structure, high power density, fast response, high resolution, and no electromagnetic interference [43][44][45][46][47][48] ; these merits make the piezoelectric actuating elements greatly suitable for the development of the miniature robots, and have captured the attentions and favors of numerous scholars. [49][50][51][52] The miniature robots driven by piezoelectric ceramics, namely miniature piezoelectric robots (MPRs), can achieve movements by converting electrical energy into mechanical energy via the inverse piezoelectric effect. [53][54][55] After decades of efforts, various MPRs with diverse mechanical structures, working principles and motion capabilities have been developed.…”

“…[ 39 , 40 , 41 , 42 ] Among them, the piezoelectric actuating elements exhibit many impressive advantages, such as compact structure, high power density, fast response, high resolution, and no electromagnetic interference [ 43 , 44 , 45 , 46 , 47 , 48 ] ; these merits make the piezoelectric actuating elements greatly suitable for the development of the miniature robots, and have captured the attentions and favors of numerous scholars. [ 49 , 50 , 51 , 52 ]…”