Abstract: Move-in-mud robot is a new-type special-use underwater robot, which can perform the hole excavating work along the planned trajectory in the mud under water. The implement of wriggle turning movement is an important link of the design of move-in-mud robot. In order to accomplish effectively the turning motion of move-in-mud robots, a 3-DOF wriggle turning joint is designed according to theories of mechanism structure synthesis for parallel robot. This joint possesses three functions, i.e. pushing, following and turning, and the movement process is divided into two parts, push motion and follow motion. The detailed analyses on the kinematics inverse problems of the two said motions are made respectively. The mathematical models and their solution procedures are given, and the virtual prototype model of such joint is created. By using MATLAB software, the kinematics inverse problems are solved. By using ADAMS software, the kinematics direct problems are solved. The case analyses on kinematics direct and inverse problems are done. The simulation results show that the design of the joint is reasonable and mathematical models are correct, which lay a foundation for the study on kinematics, dynamics, and optimization design of move-in-mud robot, and provide the theoretical basis for control system design.

Key words: Kinematics direct and inverse problems, Move-in-mud robot, Push and follow motions, Virtual prototype technology, Fault diagnosis, Gear transmission system, Time-Varying blind source separation