Abstract: On a 3-DOF cable-driven humanoid shoulder with joint angle feedback,the shoulder's function is achieved by three mutually perpendicular single-axis joints intersecting at one point.Encoders are installed on each joint to obtain the control error caused by elasticity of cables and mechanism installation.For the output coupling problem of parallel mechanism,a linear position interpolation algorithm is proposed with real-time computation of inverse kinematics and online error compensation.Besides,an optimal tension distribution algorithm avoiding tension limits is proposed to solve the tension dramatic changes and oscillation problems,in which the safety threshold is used as programming object.The real time motion control system based on PC and motion controller is designed and experiments are carried out to demonstrate the correctness of the algorithm and the effectiveness of the control system.