NURBS-based time-optimal trajectory planning on robotic excavators

Abstract

In order to improve the efficiency of the robotic excavator meanwhile to obtain its smooth running trajectory,a new trajectory planning method based on Non-uniform Rational Basis Spline(NURBS)was proposed.A quintic NURBS curve was employed to interpolate joint positions of the robotic excavator.Using the vector-valued function,by Leibniz formula,higher order derivative vector of NURBS curve was obtained to set the start and stop speeds and accelerations;and to make up the trajectory curves with continuous jerk,which passes specified joint positions.The effect of NURBS weight factor in sectional trajectory planning was analyzed.Nonlinear minimization problems under constraints were solved using sequential quadratic programming;then time-optimal trajectories were planned.Simulation and experiment results show that the proposed trajectory planning method can provide time-optimal trajectories,which satisfy kinematic constraints and the sectional trajectory optimization is effective.