Delta机器人运动轨迹动态规划方法

Dynamic Trajectory Planning of Delta Robot

针对Delta机器人末端的残余振动和抓取效率问题,提出一种基于Bézier曲线的轨迹动态规划方法,并为每段轨迹的运动周期提供设置依据。首先,以机器人路径中障碍物作为控制点的设置原则,利用多阶Bézier曲线动态调整路径中不同数量障碍物所对应的轨迹几何形状。其次,采用3-4-5次多项式对轨迹运动规律进行三维规划,获得轨迹插补点的位置、速度和加速度。最后,优化轨迹几何形状,并基于关节能量近似函数优选机器人运动周期,以满足运动过程中的高效性和稳定性要求。运动轨迹及运动规律仿真结果表明,所提轨迹规划方法能够有效规避障碍物,并且运动速度与加速度连续且光滑。在搭建的Delta机器人样机上采用所提轨迹规划方法进行抓取实验,结果表明,抓取速率可达100次/分钟,且能够有效降低运动停止后机器人末端的残余振动。

To address the residual vibration and the efficiency problems ofDelta robots,a dynamic trajectory planning method based on Bézier curve for a Delta robot is proposed to solve the problem of uncertainty in the selection of critical path points and motion period.The purpose of the critical path points setting is to enable the robot to evade obstacles in the path.Firstly,according to the number of obstacles,the trajectories can be divided into single obstacle trajectory and multiple obstacle trajectory.The 2nd order Bézier curve is used to determine the trajectory geometry when there is a single obstacle while the 3rd order Bézier curve is used to determine the trajectory geometry when there are multiple obstacles.Secondly,the 3-4-5 polynomial is adopted to plan the three-dimensional displacement along the curve and generate the position,velocity and acceleration information necessary for the interpolation points.Finally,the trajectories corresponding to different numbers of obstacles are optimized.And the motion time is optimized based on the energy approximation function of joint torques and angular rates,so that the robot's motion meets the requirements of high efficiency and stability.Simulation results show that the proposed trajectory planning method can dynamically adjust the trajectory shape according to the position and number of obstacles,and the velocity and acceleration are continuous and smooth in the process of motion.The proposed trajectory planning method is used in the pick-and-place operation on the Delta robot,and the results show that the pickup speed can reach 110 times per minute.Through the acceleration motion test,it is proved that the trajectory planning method can effectively reduce the residual vibration of the end-effector after the motion stops and the residual vibration decreases with the increase of the motion period.