Kinematic and compliance analysis for tendon-driven robotic mechanisms with flexible tendons

Compliance in tendon transmission may result in position errors for tendon-driven robotic mechanisms. As a consequence, the study of compliance of the mechanism is important for control purpose. This paper deals with the kinematic and force analysis of tendon-driven robotic mechanisms with compliant tendons. The displacement equation of tendon-driven robotic mechanisms that takes tendon compliance into account can be systematically determined from the kinematic structure. The force relations between the joint space and the tendon space are investigated. In particular, the equations relating joint torques, joint angles and tendon displacements are derived. The compliance of the mechanism is thereafter established. Dynamic equations of the system are also analyzed and system's resonant frequencies are derived through local linearization of the dynamic model. The proposed analysis can be useful for a fast evaluation for the static and dynamic performance of tendon-driven robotic mechanisms.