Research On Motion And Control Of A 6-tetrahedral Robot

In view of the status that existing mobile robot are difficult to be applied to detect the extreme land environment, such as dense crater, ravines and valleys on the planetary surface, this paper mainly studies a kind of topological six-tetrahedron robot with high mobility, ability to adapt to environment and no falling down. The robot is mainly made up of 19 rods and 8 peripheral nodes. It changes robot configurations and realize the movement of robot by stretching rods. The six-tetrahedron robot is a parallel mechanism with mobile rods, nodes and multiple closed chains, which results in the difficulties of the system control, so this paper mainly studies the movement and control of the robot that involves the kinematics, dynamics, gait planning, control and other key problems which need to be solved.This paper analyzes the inverse kinematics of topological six-tetrahedron robot briefly. Based on the structure of this robot, it can be divided into two parallel triangular platform mechanism. Using the analysis method of the triangle plane parallel mechanism, this paper analyzes the closed-form solution of robot kinematics in detail. In addition, the first-order influence coefficient of robot motion and velocity are derived, and the Jacobi matrices are obtained. For ease of topological six-tetrahedron robot control, based on Lagrange dynamics modeling, related elements such as kinetic energy, potential energy and centrifugal force of the robot rod and node are derived, and finally the dynamic equation of Cartesian space is obtained.Gait planning is the basis of realizing stable movement of topological six-tetrahedron robot. In this paper, based on finite state machine and the central pattern generator, the rolling gait planning of the robot is achieved. In addition, based on planning principles of the center of gravity and the support polygon gait, walking gait planning of topological six-tetrahedron robot is realized. Finally, the model of topological six-tetrahedron robot is established in the ADAMS software, and kinematics simulation results demonstrate the feasibility of the two kinds of gait respectively.Based on the dynamics equation of the topological six-tetrahedron robot, a decentralized adaptive control method is given and proved using Lyapunov stability theory. The numerical simulation of the existing model verifies the convergence of decentralized adaptive control. To avoid failure of adaptive control law caused by system disturbance, an approach is proposed based on decentralized adaptive control and gain correction to improve the robustness of control system. The virtual prototype of topological six-tetrahedron robot and the proposed control system are built using ADAMS and Matlab simulation software. The simulation results have verified the validity and stability of the control system.