A repetitive periodic motion planning of articulated underwater robots subject to drag optimization

In order to utilize hydrodynamic drag force on articulated robot moving in an underwater environment, a repetitive motion planning method subject to drag optimization is proposed. Repetitive trajectories, a preplanned periodic motion, are obtained from general polynomial trajectory planning method by connecting the end point of trajectory to start point by enforcing continuous motion. After drag torque is described in terms of joint angles and velocities, directional drag force in task space is derived, which is used as objective function to be optimized during a time period. The genetic algorithm (GA) is adopted to find optimal parameters composing the coefficients of polynomials. To verify the correctness of proposed method, periodic motion planning examples of simple two-link planner robot are presented in this paper.