Abstract: Tendon-sheath transmission mechanism in pull-pull configuration is common in tendon-sheath actuated robotics. Its transmission characteristics are more complex than single-tendon-sheath transmission because the two tendons will interact with each other during the working process. The transmission characteristics in different phases are studied based on our previous results of single-tendon-sheath transmission system. The torque and displacement transmission models are deduced. An experimental setup for measuring the transmission characteristics is developed and the transmission models are verified by experimental data. Influencing factors related to transmission characteristics are studied by experiments, the results shows that the transmission characteristics are determined by the total sheath bending angle, tendon pretension and the friction level between sheath and tendon, rather than tendon velocity and sheath bending radii.

Key words: tendon-sheath transmission system in pull-pull configuration;backlash-like;hysteresis-like;surgical robot