Solution to redundant drives of cable-driven parallel robot: Incomplete-DoF mode

Due to the fact that cables cannot be pushed and can only be pulled, cable-driven parallel robots (CDPRs) frequently employ redundant drives. Redundant geometric constraints in the system can result in uncontrollable internal forces, potentially causing damage to the robot. To overcome the internal force resistance, the incomplete degrees-of-freedom (DoF) driving mode is introduced, meaning that not all the DoFs generated by the geometric constraints on the end platform in the task space are bidirectional. The paper presents a conversion algorithm and conducts experiments on two platforms: a 4-cable, 2-DoF robot and an 8-cable, 6-DoF robot. The experimental results show that, compared to the traditional complete DoF driving mode, the proposed incomplete DoF driving mode leads to a slight reduction in accuracy but significantly reduces internal force resistance and improved energy efficiency. This study provides insights into the design of drive modes for redundantly actuated parallel robots.