A robotic testbed for zero-g emulation of spacecraft

This paper presents an emulating system for zero-gravity (0-G) emulation of a ground spacecraft in an earthbound (1-G) laboratory environment using a controlled manipulator. Such an emulating system allows testing of the spacecraft, e.g., a satellite, with all of its hardware in place, and it is applicable to the case of either a rigid spacecraft or a flexible spacecraft. The controller of the manipulator is developed to virtually change the mass properties of the ground spacecraft and to replicate either the free-space motion or the orbital motion dynamics of a flight-spacecraft. The stability of the system and the effects of disturbance and force sensor noise on the fidelity of the emulating system is thoroughly analyzed. The concept of the 0-G emulation of spacecraft is demonstrated by performing experiment for emulation of a satellite using a robotic testbed at the Canadian Space Agency (CSA).