Abstract: Tendon flexibility and friction force between contact surfaces lead to tendon-sheath transmission characteristics nonlinear. To realize the precision control, the static and dynamic models of transmission characteristics about the spatial arbitrary shape tendon-sheath actuation system are established, and the LuGre friction model is applied in dynamic model simulation. To validate the static theoretical analysis and dynamic simulation results, the testing table is developed, and the experimental results coincide with them. The results indicate that nonlinear phenomena such as dead zone, hysteresis and directional dependence present in the force-displacement transmission characteristics are relative to friction coefficient between contact surfaces, total curvature and tendon elasticity coefficient, but have nothing to do with torsion, total curvature radius and transmission speed. Studies with the nonlinear transmission characteristics have significance reference to the force-displacement coordination control and object accurate grasping of tendon-sheath actuated robots working under narrow space.

Key words: Dynamic friction model, Modeling analysis, Nonlinear, Tendon-sheath transmission characteristics