Abstract: As the requirement of high accuracy in trajectory tracking, the control result which based on the kinematics model can’t meet the requirements, a five free degree wheeled mobile welding robot is concerned, which is differential driven by two behind wheels. The dynamics model and the output feedback linearization process are researched. A trajectory tracking control method for a wheeled mobile welding robot is also presented. The non-complete dynamic model for the four wheeled mobile welding robot is established. The exact feedback linearization model is proposed based on the nonlinear model. The control law is developed by variable structure control of sliding mode for ensuring the robot velocity asymptotically approaching to the desired velocity in uncertain system dynamics. A sliding mode controller is designed by selecting linear sliding surface and exponent reaching law. Used the Lyapunov stability theory to prove the stability of the robot and its tracking error convergence．The control law satisfies the trajectory tracking requirements for the wheeled mobile robot and has good robustness. Simulation results prove the effectiveness and correctness of the control law.

Key words: wheeled mobile welding robot;dynamic model;trajectory tracking;feedback linearization