Control of force transmission for cable-driven actuation system based on modified friction model with compensation parameters

The cable-driven system characterized by tendon-sheath structure has been widely applied in the field of flexible actuation due to its lightweight, durability, and flexible layout. However, the inherent issues of friction and backlash in the mechanism result in hysteresis, which impose certain limitations on the application of efficient and high-precision actuation scenarios. In this study, a novel control method of force transmission for tendon-sheath actuation system is proposed, based on modified friction model with compensation parameters. The control method adopts a hybrid control strategy based on inverse model feedforward control, which improves the response time and disturbance rejection capability of the cable-driven system. Real-time detection and compensation of cable bending angles are achieved by introducing an angle identification model, which significantly improves system stability. Experimental results demonstrate that the proposed control strategy increases the response speed and accuracy of the force control for the cable-driven system, with a steady-state maximum peak error of 0.157 N, a step response time of 0.102 s, and a root mean square error of 0.117 N under sinusoidal signals. Finally, the cable-driven actuator and control strategy are applied to the assisted exoskeleton for elbow joint in extravehicular spacesuit, helping wearers overcome joint resistance in working conditions. The results show that when the elbow joint bending angle is 40°, the maximum interaction torque in the bending direction is reduced from 7.94 N m to 0.48 N m, with an average assistance efficiency of 71.8%. The exoskeleton system provides effective assistance to wearers during joint movements and greatly reduces biological energy consumption.