- A new motion control approach for an underwater robot with four tilting thrusters is proposed and investigated in this paper. The tilting thruster arrangement results in overactuated system which carries out six degree of freedom (DOF) motion with four rotatable thrusters. The dynamic model developed for the robot has a highly nonlinear thrust vector map because of tilting angles. Backstepping control, a non-linear control method is applied to this robot model for continuous tilting motion. The system stability is guaranteed, and the tracking errors asymptotically converge to zero by Lyapunov stability theory. Finally, numerical simulations illustrate the performance of the derived cascaded tracking control technique. © ICROS.