Design of a biarticular robotic manipulator and its control in the rotating coordinate system

In human-interacting applications of the robotic manipulators, it is important for the robotic manipulators to emulate the dynamic characteristics and performance of human motions. To this end, a biarticular actuation mechanism is introduced to solve the kinematics and dynamics of a two-link manipulator in this paper. For an effective and convenient expression of the equation of motion from inspiration of the human musculoskeletal structure, the kinematics and dynamics are analyzed in the rotating coordinate system, which enables the sophisticated and intuitive control of an end-effector. In order to provide a general platform for designing control algorithms and state observers, the dynamic equation is formalized into a state-space equation. A feedback controller is designed (1) to reject undesired dynamic couplings caused by the inherent mechanical structure and (2) to realize the desired dynamic characteristics to achieve position control of the end-effector. The proposed methods are verified by experimental results in this paper.