关键词: Delta并联机器人, Lamé曲线, 参数优化, 轨迹规划, 拾放操作

Abstract: A method of trajectory planning for high-speed Delta parallel robots in pick-and-place operations is presented. The transitions between the vertical and horizontal segments of the operation trajectory are smoothed with Lamé curves, thus determining the overall shape of the trajectory in Cartesian space. High order polynomials are adopted to plan the one-dimensional displacement along the curve and generate the position, velocity, acceleration information necessary for the interpolation points. Trajectory information in Cartesian space is mapped back to the joint space by using the Delta robot’s kinematics and dynamics models. In order to optimize the Lamé curve’s geometric parameters, an energy-like function based on joint torques and angular rates is thus defined. The trajectories planned are finally tested on an experimental platform. The residual vibrations as the robot’s end-effector reaches the terminal are recorded and then compared under different Lamé curve parameters. These results verify that the optimized trajectory has a better performance practically. The planning method discussed could lead to trajectories which satisfy operational requirements.

Key words: delta parallel robot, lamé curve, optimization, pick-and-place operation, trajectory planning