Design, self-calibration and compliance control of modular cable-driven snake-like manipulators

The high flexibility of cable-driven snake-like manipulators (CDSM) makes them well-suited for tasks in narrow and unstructured spaces. However, ensuring both stiffness and load capacity while maintaining good compliance for safe human-robot interaction is challenging. We design a modular cable-driven snake-like manipulator (MCDSM) and improve its active compliance through impedance control. Firstly, the detachable arm segments of the MCDSM can adapt to multiple tasks. The modular drive units and plug-in drive boxes facilitate quick installation and maintenance. Furthermore, the modified kinematic model considers the torsion angle information of the detachable arm segments. Based on this model, a self-calibration method using redundant cable length is proposed for cable space to joint space. Moreover, a dynamic model for the MCDSM is established. An optimization method for cable tension in joint space is proposed to eliminate the coupling phenomenon during tension control. Finally, a compliant control method for the MCDSM is presented by combining the inner loop for the cable tension control. The feasibility of the proposed methods is demonstrated through simulations and experiments with a prototype.