Abstract: To meet the high-accuracy control requirements of the coordinated operation task performed by the Robonaut under unknown interferences, a coordinated impedance control method based on disturbance observer is proposed. Firstly, geometric constraints and force constraints between the object and the Robonaut are analyzed to establish a unified dynamics model of the object and the Robonaut. Secondly, a momentum disturbance observer is designed for the coordinated control system of the Robonaut based on the generalized momentum of the robot. Thirdly, an impedance control method is designed for coordinated operation of the Robonaut based on the disturbance observer, combining with the unified dynamic model. Finally, a numerical simulation is carried out to verify the proposed method. Results show that the position error of the object is controlled within the order of 10^-5 m, when the arms are influenced by unknown interferences. The proposed method effectively reduces the influence of the unknown interferences on the accuracy of the object pose control, and ensures the high precision control of the coordinated operation task.