Shohei Niwa

Stability of linear time-varying systems with state dependent noise

The mean-square stability of linear time-varying systems with state dependent noise is considered. The stability conditions concerning the magnitude of the state dependent noise are presented.

Robust Control of Space Manipulator.

Robotics and automation in space development, such as construction of space structures or servicing of satellites, will be needed in order to reduce the workload of astronauts, and increase the operational efficiency and safety of space missions. In this paper, making use of the sliding mode control method, a design for the robust control system of a space manipulator is presented. A model of the space manipulator which has an end effector for capture of a target floating in space is considered. The effectiveness of the proposed method is demonstrated by the computer simulations and the experiments using a two-dimensional experimental facility which simulates a two-link space manipulator system. Its relative merit is assessed through comparison with other methods.

Force Control of Docking Actuator

Abstract This paper presents a research on control system design for actuators used for the docking system in space. An adaptive control technique is applied to design an compliance control strategy which adaptively adjust the actuator force for different kinetic energy of the docking target. An experimental docking system is developed in order to show the validity of the control system and to compare theoretical and experimental performances

Control system design for docking actuator

Research on the control system design for actuators used in a space docking system is presented. The phase of velocity matching and that of attenuation in the soft docking process are investigated by utilizing an experimental docking test facility which includes an electromechanical actuator and an air-lifted docking target. In the matching phase, the actuator is accelerated to match the velocity of the approaching target. A design of feedback control is shown for this phase, making use of the Kalman filter to obtain target speed estimation from the relative distance observation. In the attenuation phase, the actuator is decelerated to attenuate the kinetic energy of the target. The most effective way of attenuation is considered to be constant acceleration attenuation. A control method is presented to attain this type of attenuation. Another method is applied to design a compliance control strategy which adjusts the actuator force for different kinetic energies to the docking target.<<ETX>>