Implementation of Path-Following Control of Lizard-Inspired Single-Actuated Robot Utilizing Inverse Kinematics

The purpose of this paper is to implement a path-following control system based on the kinematics of the Lizard-Inspired Single-Actuated robot (LISA). LISA is a new type of robot that mimics the quadrupedal walking morphology of lizards with a four-bar linkage mechanism and can realize both propulsion and turning with 1 degree-of-freedom. To achieve this purpose, this paper takes 3 approaches: kinematics formulation, control system design, and experimental verification. In the kinematics formulation, we formulate LISA’s turning angle, stride length, posture, propulsive direction, curvature, and position coordinate. In control system design, we design a control system that converges not only the distance error but also the posture error and control input. Conditional equations that can achieve these 3 control targets are formulated using forward kinematics and reference path functions. The experimental verifications were carried out to verify the effectiveness of the designed path-following control system using three types of paths: linear, circular, and combined linear and circular. As a result, it was confirmed that the Root Mean Square values for the control input, the distance error, and the attitude error were sufficiently small in steady state. Therefore, it was confirmed that the 3 control objectives had been achieved.