Cable-Constrained Synchronous Rotating Mechanism (CCSRM) has an important application prospect in the field of cable-driven robots, which can greatly reduce the number of driving motors while ensuring the light and slender body. However, there are obvious cable friction effect and elastic deformation in CCSRM. These nonlinear characteristics have a significant impact on synchronous motion performance. In this letter, a model of CCSRM considering cable friction is proposed, which integrates the effects of cable pretension, elastic deformation, and friction between cable and pulley on system characteristics. The distribution law of cable tension under the influence of friction force and the phenomenon of motion hysteresis caused in reverse rotation are emphatically discussed. Then, an improved LuGre friction model is proposed to solve the problem of line contact friction between cables and pulleys. Further a dynamic model of CCSRM is established to simulate the motion characteristics of the whole process, including the discontinuous friction phenomenon in reverse rotation. Finally, an experimental prototype of two-axis synchronous rotating system is built, and the friction coefficient is identified. The experimental results show that the dynamic model can well simulate the motion characteristics of CCSRM.

The application requirements of the tendon-sheath mechanism in the field of precision machinery are becoming increasingly extensive. However, the contact friction between the tendon and sheath seriously affects the transmission accuracy. In the case of unavoidable friction, optimizing the tendon transmission path to reduce tension loss and elastic deformation has become an important research direction. In this article, the influence law of the tendon transmission path on the tension and displacement transmission is obtained using the two parameters related to the curvature of the transmission path: total bending angle and equivalent tendon length. Then, based on the optimal control theory and minimum principle, the different transmission path solutions of the minimum tension loss, the minimum tendon deformation, and the coupling of tension and displacement are obtained; the numerical optimization method verifies the correctness of the proposed theory. Finally, an optimal design of a tendon-constrained synchronous rotation mechanism for the manipulator is carried out, and the linkage performance is greatly improved by optimizing the transmission path.

Space activities such as asteroid capture and on-orbit construction of ultra-large spacecraft will significantly increase the operating distance and torque requirements of the space manipulator. In this article, we propose a new cable-driven joint module for space robots based on the idea of a cable-stayed bridge structure, and deeply investigate its driving properties. First, we give the structural design for the cable drive joint module. Using a clever combination of drive cables, special hinges, and spreader construction, the designed joint module allows $\pm 180^{\circ }$ rotation and can achieve high torque and high stiffness properties at a low quality cost. Second, the kinematics model, statics, and stiffness model of the joint module are established. On this basis, the kinematic, Jacobi, torque, and stiffness characteristics of the joint are discussed in detail. Finally, we built an experimental system of the cable-driven joint module, and tested the repeatability, torque, and stiffness of the joint module. The results show the unique characteristics of the mechanism and verify the correctness of the theoretical model and characteristic analysis.

The space cable-driven continuous manipulator (SCCM) has a slender structure, ultra-high degrees of freedom, and a low mass, which make it suitable for equipment inspection and maintenance operations in an unstructured and limited space environment. In this paper, the SCCM including the cable network and plenty of joint links was deeply modeled. Firstly, the mapping relationship between the cable-driving space, joint space, and task space of the SCCM was studied, and the complete kinematic relationship of the SCCM was established. Secondly, the stiffness components of the SCCM are discussed, and the stiffness modeling method of each part is given. Finally, the Cartesian space equivalent stiffness model of the end was established. Then, a dynamic co-modeling method of Matlab + Adams is proposed, which greatly improved the modeling efficiency while ensuring the modeling accuracy. Finally, based on the stiffness model, the end stiffness characteristics of a specific configuration were analyzed, and the influence of the cable tension on the stiffness and frequency of the manipulator was analyzed. Based on the dynamic co-modeling, the task trajectory dynamics’ simulation analysis and space slit crossing experiment were carried out, which verified that the designed SCCM can meet the needs of slit crossing.

The cable-driven serial manipulator (CDSM) combines the flexibility of continuum robots with the high load-bearing capacity of rigid robotic arms. To ensure safe interaction with the surrounding environment and humans while enabling dexterous operations, tactile perception plays a crucial role as a sensory feedback source. This letter proposes a real-time multi-contact estimation method with dynamic compensation to address the challenges posed by nonlinear modeling errors, including friction effects from sliding cables, and coupled multi-contact force interactions. First, a unified joint-space perception model is developed to decouple external interactions from the dynamics of the driving system. Second, a directional-reversal zone integrator is designed to handle drastic state variations during motion reversals, complemented by a Gated Recurrent Unit (GRU) network to mitigate the effects of unmodeled dynamics. Third, a position-continuous optimizer is introduced to reduce solution instability caused by the coupling between external forces and contact positions. Experimental validation on a CDSM prototype demonstrates a 63% reduction in positional root mean square error (RMSE) with the synergistic combination of dynamic compensation and the enhanced solver. The implemented real-time control framework demonstrates an accuracy of 4.0 mm/1.3 N in static scenarios and 3.7 mm/2.5 N precision during dynamic operations, sustained at a 50 Hz control frequency.