A Time-optimal Trajectory Planning Algorithm for Six-degree-of-freedom Robots Based on NURBS Curves

In this paper, we research and analyse the practical needs of robotic arm to complete the complex path planning of robotic arm and smooth transition of multi-attitude in the shortest time under the premise of satisfying the dynamics constraints, and put forward the time-optimal trajectory planning based on NURBS curves and multi-attitude interpolation algorithm based on quaternion with NURBS curves. Using the complex nature of quaternions, the quaternions are converted into three-dimensional space points for curve interpolation, and finally converted back to quaternions to achieve the second-order continuity of multi-gesture interpolation; a time-optimal trajectory planning algorithm based on NURBS curves is designed, which discretises the curves, and fits the NURBS curves using the discrete points. At the same time, the optimal rate solution under all the constraints is calculated point by point according to the discrete points on the motion path, and the optimal velocity curve satisfying the dynamics constraints is obtained, so as to achieve the time-optimal trajectory planning. Finally, the feasibility of the designed trajectory planning algorithm is verified in the simulation software and experimental platform, and it is proved that the algorithm can effectively improve the running speed by at least 30%.