Motion Planning of Sampling Flexible Manipulator on Planet
摘要: 为适应行星表面较大范围的采样要求及系统减重的需求,采样机械臂通常是细长形臂杆加多关节组成的连杆型关节机械臂,这使得抑制柔性振动成为机械臂控制系统的研究重点。针对采样机械臂的工作过程,提出带抛物线过渡的平滑轨迹规划方法,即在运动过程中使加速度连续,避免关节转动的力矩突变,并且最大限度降低峰值。首先建立基于D-H法的机械臂运动学方程,然后在考虑臂杆及关节柔性的动力学模型环境下,进行变加速—匀速—变减速的笛卡尔空间加速度连续平滑轨迹规划运动,达到减小柔性臂振动、提高定位精度的目的。仿真结果表明,在运动规划中引入抛物线过渡的加速度连续环节、降低加速度冲击可以明显改善运动平稳性,对提高动态跟踪精度有直接作用。Abstract: In order to adapt to a wide range of planetary surface sample acquisition and requirements of weight optimization, manipulator usually consists of several slender arms and rotary joints. This makes the flexibility compensation and vibration suppression become research focus in the manipulator control system. In this paper, a smooth trajectory planning method with parabolic contour for sampling motion of manipulator is proposed. In the motion process acceleration is made to be continuous to avoid joint torque mutation and debase the peak value farthest. Firstly, the kinematic equations of manipulator based on D-H and dynamics model with flexible deformation of joints and arms are established. Then, the variable acceleration-uniform motion-deceleration trajectory is planned in Cartesian space, which acceleration is consistent and smooth. Finally, the typical tasks of manipulator are simulated. Results indicate that this method is useful to make acceleration of joint motion continuous. This control strategy can obviously improve dynamic tracking accuracy and position precision.