Design Optimization of a Novel Tripedal Locomotion Robot Through Simulation and Experiments for a Single Step Dynamic Gait

摘要

This paper presents the concept and design of a unique three-legged walking robot, and results from the simulation and experiments of a single step tripedal gait. The STriDER (Self-excited Tripedal Dynamic Experimental Robot) incorporates aspects of passive dynamic walking into a stable tripedal platform and is capable of changing directions. To initiate a step, the legs are oriented to push the center of gravity outside of the stance polygon, and as the body of the robot falls forward, the swing leg naturally swings in between the two stance legs and catches the fall. Once all three legs are in contact with the ground, the robot regains its stability and the posture of the robot is then reset in preparation for the next step. The changing of the direction is done by a unique way of changing the sequence of which of the three legs is the swing leg. To guide the design of the robot, a dynamic model was developed and a simulation of a single step tripedal gait was performed to allow for tuning of several design parameters, including the mass properties and link dimensions. By considering the two stance legs as a single effective link connected to the ground, the robot can be modeled as a planar four-link pendulum in the sagittal plane. Further development of the simulation also allowed for optimization of the design parameters to create an ideal gait for the robot. A self-excited method of actuation, which seeks to drive a stable system toward instability, was used to control the robot. This method of actuation was found to be robust across a wide range of design parameters and relatively insensitive to controller gains. The design of the first prototype and result from the experiments are presented with a discussion of future work.