Whole-body control of redundant hybrid cable-driven robot with manipulator: hierarchical quadratic programming approach

A redundant Hybrid Cable-Driven Robot (HCDR), which is an integration platform of a robotic manipulator and a Cable-Driven Parallel Robot (CDPR) has numerous advantages including an extensive operational range and high performance in task execution. However, it is difficult to control the redundant HCDR due to the dynamic coupling between a manipulator and the CDPR and the redundancy resolution. To solve these issues, this paper introduces a novel whole-body controller strategy for the redundant HCDR by using Hierarchical Quadratic Programming (HQP). First, the whole-body nonlinear dynamics with cable tensions and manipulator torques is proposed. Then, with the HQP-based scheme, the proposed controller can generate the optimal tensions and torques for the redundant HCDR to generate whole-body motions without dynamic interference between the CDPR and the manipulator. In addition, singularity and joint limit avoidance algorithms are proposed in this paper, because the proposed controller can handle prioritized tasks with inequality constraints as well as equality constraints. The proposed control scheme has been implemented on the redundant HCDR with 8-cables and 7-DoFs manipulator, and its performance is demonstrated through various scenarios in high-precision simulator.