Modeling and Experimental Verification of a Cable-Driven Rolling Joint System Considering Preload and Friction Effect

In the realm of cable-driven robotics, the cable-driven rolling joint (CDRJ) is a transformative innovation that effectively increases stiffness based on biomimicry while maintaining the robot's slim and lightweight structure. This study presents a comprehensive model of CDRJ that meticulously considers the effects of cable friction, integrating the influences of cable pretension, elastic deformation, and the frictional interaction between the cable and the pulley on the system's performance. The research delves into the distribution law of cable tension influenced by frictional forces and the consequential motion hysteresis observed during reverse rotation. An enhanced LuGre friction model is introduced to address the complexities of line contact friction between cables and pulleys. Building upon this, a dynamic model of CDRJ is established, capturing the motion characteristics throughout the process, including the discontinuous friction phenomena inherent in reverse rotation. This article culminates with the construction of an experimental prototype of a cable rolling joint system, through which the friction coefficient is determined. Experimental results corroborate the dynamic model's proficiency in simulating the motion characteristics of CDRJ, underscoring its potential for accurate tension prediction and force assessment within intricate pulley systems. Meanwhile, the generalized model of the pulley–cable system developed in this research may be applied in the fields of biomechanics, prosthetics, and bionic design, providing new insights into various cable-driven systems.