Research on Full Closed-Loop Control of Suspended 4-Cable Driven Parallel Mechanism with Multi-Source Sensor Fusion

This study presents a real-time, fully closed-loop control strategy to enhance the trajectory tracking accuracy of an under-constrained, suspended 4-cable-driven parallel mechanism (CDPM). Solving the inverse kinematics for such systems is challenging, typically forcing a trade-off between computational efficiency and control precision. To overcome this, the research first established an empirical model by identifying a functional relationship that couples the moving platform's translational and rotational motions through numerical simulation. This model was then innovatively integrated into a double closed-loop PID controller, avoiding the high computational cost of real-time numerical iteration and preventing cable pseudo-drag. Experimental results demonstrated a significant performance improvement over open-loop control. The proposed strategy achieved superior stability, accuracy, and real-time performance. The average trajectory tracking error was reduced by 84.5% (from 2.2312 mm to 0.3465 mm), and the Fréchet distance, measuring trajectory similarity, improved by 70.0%. This empirical model-based approach provides an effective solution for the real-time control of complex CDPMs, offering critical support for their use in high-precision industrial applications.