Dynamically equivalent manipulator for space manipulator system. 2

We propose the concept of the dynamically equivalent manipulator (DEM) of a free-floating space manipulator (SM) system. The dynamically equivalent manipulator can be physically built and used as an experimental testbed for the study of the dynamic performance and task execution of space robots. As it is a fixed-base manipulator, there is no need to resort to complex mechanisms to simulate the space environment. In this paper, we discuss two important issues associated with the DEM concept. First, we demonstrate the property of conservation of angular momentum and verify the validity of the DEM under free-flying conditions (i.e., when the SM base attitude is controlled via reaction wheels). Next, we investigate the effect of model uncertainty in the space manipulator and how it maps as errors in the parameters of the DEM. We derive explicit expressions for the error mapping and present a case study.