On the Hexapod Leg Control with Nonlinear Stick-Slip Vibrations

Abstract

In the paper the control problem of the six-legged walking robot is studied. In order to find the relationship between commonly used by insects gaits (trajectory of the foot point) and stable trajectory of mechanical systems, at first we analyse various previous papers and the gaits of the real insects. For control the motion of the tip of the robot leg a nonlinear mechanical oscillator describing stick-slip induced vibrations further referred as central pattern generator (CPG) has been proposed. The advantages of the proposed model has been presented and compared with other previous applied mechanical oscillators. The possibility of control of the tip of the robot leg via changing parameters characterized oscillator working as a CPG has been discussed. Time series of the joints and configurations of the robot leg during walking are presented. The obtained numerical solutions indicate some analogies between the characteristics of the simulated walking robot and animals found in nature. Moreover, some aspects of an energy efficiency analysis (in order to reduce the energy costs) are discussed for the analysed system and the whole hexapod robot. In particular, we discuss the interplay of the proposed gait patterns and the system energy cost.