HD-CDAM: A Heterogeneous Differential Cable-Driven Anthropomorphic Manipulator With High Payload-Weight Ratio

With the increasing demand for lightweight, large payload-to-weight ratio, and highly dynamic robotic arms for general-purpose applications, conventional designs inevitably face a significant trade-off among safety, payload capacity, and motion agility. This letter presents a 7°-of-freedom cable-driven anthropomorphic manipulator based on dual/triple-joint differential mechanisms (HD-CDAM). First, we systematically analyze the principle of dual-joint differential mechanism and propose a general design methodology for triple-joint differential mechanisms, subsequently developing six distinct types of triple-joint differential modules. These modules enable dynamic redistribution of output torques from two or three actuators to individual joints through a cable-driven transmission system, significantly enhancing each joint's maximum load capacity. The proposed HD-CDAM comprises a triple-joint differential mechanism for shoulder, dual-joint differential mechanism for elbow, and dual-joint differential mechanism for wrist, with all actuators optimally placed close to the base to improve mass and inertia distribution. Experimental results show that the approximately 1 m-long HD-CDAM has a total moving part mass of 6.65 kg, a maximum payload of 12 kg (payload-to-weight ratio: 1.80), a maximum end-effector velocity of 11.19 m/s, and a repetitive positioning accuracy of 0.22 mm, demonstrating its repeatability, dynamic performance, and payload capability.