The mobile servicing system (MSS) is an integrated mobile remote manipulator system under development by SPAR Aerospace Limited for the Canadian Space Agency. The MSS includes two separate manipulator systems, both possessing kinematic redundancy, and will be used in the construction and maintenance of the International Space Station Freedom. This paper presents the concepts for the collision avoidance system for these manipulators. The collision avoidance system uses a collision prediction system as a front end. The collision prediction system is based on an octree model of the environment and provides the location, direction, and distance of impending collision(s). Given the information, the system calculates the joint rate commands that will achieve automatic collision avoidance. Computer simulation of the Space Station remote manipulator system (SSRMS) operating in an octree model of the Space Station is shown, as well as hardware demonstration using a large-scale ground testbed for the special purpose dexterous manipulator (SPDM).>

It is shown that a servomechanism with only position/velocity functions can obtain a force control function using the adaptive theory (model-referenced adaptive system and model-referenced control). Experimental results of both the servomechanism and the single-degree-of-freedom force control of the manipulator show that this method leads to suitable force control when the object stiffness changes greatly. The advantage of this method is that a force control function is achieved by implementing software to identify the object stiffness without changing hardware.>