Optimal Trajectory Planning of a Cable-Driven Parallel Robot by Direct Collocation Approaches

Subject Areas : robotics

Milad Badrikouhi ¹ , Mahdi Bamdad ²

1 - Mechanical and Mechatronics Engineering School, Shahrood University of Technology, Iran
2 - Mechanical engineering department, Shahrood university of technology

Received: 2024-02-29 Accepted : 2024-09-08 Published : 2024-10-20

Keywords: B-Spline Interpolation Curves, Cable-Driven Parallel Robot, Direct Collocation, GPOPS-II, Trajectory Planning,

Abstract :

Trajectory planning in cable-driven robots is more challenging than rigid-link ones. To maintain the robot control, the cable tensions must be positive during motion. This paper presents a direct collocation approach to solve the optimal trajectory planning based on the minimization of a robot's tension and tension-rate objective functions. Besides, during robot motion, the cables must be tensile. The configuration of a cable parallel robot composed of a 3-cable and a prismatic actuator neutralizes the moving platform’s weight while improving tensionability. To generate smooth trajectories, the proposed method is compared with two standard approaches: GPOPS-II software package which uses Legendre-Gauss-Radu quadrature orthogonal collocation polynomials and direct collocation by using B-spline interpolation curves. Despite the efficiency of using B-spline functions in trajectory planning, numerical simulations demonstrate that the Hermite-Simpson direct collocation approach has a substantial benefit in the computation cost and accuracy for trajectory planning of a cable-driven parallel robot. Also, by choosing appropriate constraints and cost functions, the cable forces in the parallel robot can be well managed.

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