Compensation control and simulation of a tendon-sheath transmission system applied to lower limb exoskeleton robots

Abstract

The tendon sheath system is widely used in occasions such as space limitation and long-distance transmission due to its simplicity, flexibility, and remote transmission ability. However, the non-linear characteristics produced by the friction and the flexibility of the tendon reduce the value of engineering applications. And also the change of pretension caused by curvature changing will lead to slack or disconnect of the system. In this paper, based on the previous researches of the tendon sheath, an elastic device connected in series with a double tendon sheath and a friction compensation law with time-varying accumulated bending angle were proposed. The proposed method can significantly reduce the change of pretension caused by bending angle change, with MAPE is 2.34% while the previous method is 25.93% and can significantly improve the anti-interference ability of the system. The proposed method was verified by a simulation and will be applied to the lower limb exoskeleton robots in subsequent research.