Obstacle Avoidance and Near Time-Optimal Trajectory Planning of a Robotic Manipulator Based on an Improved Whale Optimisation Algorithm.

Aiming at the obstacle avoidance trajectory problem of robotic manipulators in operation space, a combinatorial optimisation solution of the obstacle avoidance path and near time-optimal trajectory planning is proposed. The robotic manipulator and the obstacles are modelled by a swept sphere volume (SSV) envelope and a capsule envelope, respectively. Based on the target offset and the target preference expansion strategy in the repulsion field, an improved RRT* algorithm is adopted to avoid collision to realise obstacle-free path planning at the end-effector level in Cartesian space and the link level in joint space. The thresholds of velocity, acceleration and jerk are set as constraints, and the interval time between nodes is optimised as position information of the improved whale optimisation algorithm. Near time-optimal trajectory planning of robotic manipulators with motion constraints is further completed. The IWOA obtains a high-quality initial population by covering the search space, and the population is updated by the thermal memory (TM) to improve individual quality. Thermal exchange optimisation (TEO) is applied to enhance the exploitation performance of IWOA, and the hierarchical structure strategy is introduced to explore potential optimal solutions. The simulation results show that the method limits the jerk of the robotic manipulator, ensures smooth movement and has higher obstacle avoidance ability and work efficiency than previous methods. [ABSTRACT FROM AUTHOR]