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On-ground experiment for space robotic system is essential to validate constructed robotic system prior to launch. This paper presents an integrated on-ground experimental environment for orbital robotic system. The experimental environment utilizes an air-floating testbed to realize twodimensional micro-gravity environment on ground. As manipulation system, the constructed environment adopts a groundbased manipulator and a free-floating robot. In order to verify the emulated micro-gravity environment, two cases are tested: the impulse-momentum relationship between a ground-based manipulator and a free-floating target, and the conservation of momentum in a free-floating robot. Both results conclude the validity of the constructed experimental environment for on-ground micro-gravity emulation.

It is essential to perform dynamic simulation in order to verify the safety of capture operation at time of contact between the grapple fixture of the H-II Transfer Vehicle (HTV) and the Latching End Effector (LEE) of the Space Station Remote Manipulator System. This paper presents the contact dynamics model for a snare wire inside the LEE in capturing the grapple fixture of the HTV. An explicit method for modeling contact dynamics is chosen so as to achieve a simple form and low computational cost in dynamic simulation. A contact model is developed using a rigid bar (grapple fixture) and a rigid wire. Wire stiffness is derived from the simplified equation of motion of the wire. The proposed stiffness model enables one to predict contact force during capture operation. Experimental measurement of the wire stiffness in static conditions verifies the proposed stiffness model. For the verification of the proposed model in dynamic conditions, a contact dynamics experiment is conducted using an air-floating test bed, which is capable of emulating two-dimensional planar micro-gravity environment. The experiment and corresponding dynamic simulation confirm the validity and usability of the proposed contact dynamics model.