Motion Control of Mobile Cable-Driven Parallel Robot via Gain Scheduling Strategy

This paper presents a trajectory generation and control strategy for a Mobile Cable-Driven Parallel Robot (Mobile CDPR), enabling it to move from an initial position to an equilateral triangular formation while the end-effector altitude is maintained. A fifth-degree polynomial trajectory is generated to coordinate the motions of the three mobile bases and the cable-winch system. The evolution of cable tensions along the trajectory is analysed through a wrench-based model to ensure that positive tensions are preserved throughout the motion. To execute the trajectory on a physical prototype, a control strategy combining feed-forward angular-velocity inputs with Proportional-Integral (PI) feedback is implemented. The PI gains are adjusted online through a gain-scheduling mechanism driven by left-right wheel error discrepancies so that traction asymmetries caused by varying cable tensions are mitigated. The approach is validated through four repeated experiments, during which tracking accuracy is preserved and tensions remain feasible across all motion segments.