2自由度绳索牵引并联机器人的高速点到点轨迹规划方法

合理的轨迹规划方法可以提高机器人运动控制的平稳性、快速性和工作效率。当前绳索牵引并联机器人的轨迹规划方法主要采用多项式函数和三角函数满足平稳性要求,但规划算法复杂、快速性较差。针对一种2自由度绳索牵引并联机器人,根据动力学模型推导绳索拉力的单向性约束条件,提出一种新的点到点轨迹规划方法——S型-梯形组合规划方法。考虑到具体的点到点轨迹包含若干个需要依次到达的目标点,构成起始段、中间段和终止段三种不同的运动段,故采用S型-梯形组合规划方法分别设计这三种运动段的速度曲线,使得机器人在起始点和终止点的加速度为零,而中间若干点的加速度不为零,实现动态轨迹规划。仿真试验表明所提出的规划方法不仅可以满足绳索拉力的单向性约束条件,且加速度为简单的一次曲线,可以实现高速的点到点运动。

High-speed Point-to-point Trajectory Planning of a 2-DOF Cable Driven Parallel Manipulator

Suitable trajectory planning methods can improve the smoothness, rapidity and efficiency of motion control of robot. Polynomial and trigonometric formulation are often adopted to realize smooth trajectory planning for cable-driven parallel manipulator, while the two approaches are complex and have weak rapidity. A new combined planning method with S-trapezoid curve is proposed for the point-to-point motion of planar 2-DOF cable-driven parallel manipulator, and the unilateral constraints on cable tensions are computed according to the dynamic model. Considering the specific point-to-point trajectory includes a list of target points that must be reached in sequence, thus it can be divided into the initial segment, the middle segment and the final segment. And then the combined planning method with S-trapezoid curve is applied to plan the velocity curve of the three segments. The acceleration is zero at the initial and final point, while it’s nonzero at the middle points. The dynamic trajectory planning can be realized with this state. The proposed planning method is implemented on a 2-DOF cable-driven parallel manipulator, and the simulation results indicate that the unilateral constraints on cable tensions could be satisfied and the acceleration curve is simple first-order curve, thus high-speed point-to-point motion could be realized.