Two prototypes of a robot known as the Multi-module Deployable Manipulator System (MDMS) have been developed in our laboratory. This manipulator is intended for carrying out research in space platform-based robotics. In the present paper, this manipulator is used in laboratory-simulated capture of an orbiting satellite. A model-based predictive controller is developed and implemented in the MDMS. Using the controlled manipulator, laboratory experiments are carried out to study autonomous capture of a free floating and spinning target. The objective is to evaluate the performance of the predictive controller for the capturing task. A planar prototype MDMS is used as the chaser robot in the experiments, and the target satellite is simulated within the controller. The model of the target satellite assumes that it is free of any external torques and involves rotations within the plane of operation of the MDMS prototype. The predictions for the chaser robot are based on a model of the MDMS, linearized about the starting configuration of the task. An unconstrained predictive controller is used in the present experiments. The results from tracking various moving targets are presented, with and without predictions of the target movement. The performance is shown to be quite satisfactory.
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