Autonomous Robotic Capture of a Satellite Using Constrained Predictive Control

This paper investigates the use of model-based predictive control for the capture of a multi-degrees-of-freedom object that moves in a somewhat predictable manner, using a deployable manipulator. The study is conducted through both computer simulations and ground-based experiments with the intended application focused on automating the robotic capture of a free-floating and spinning satellite. The present investigation uses an innovative manipulator known as the multi module deployable manipulator system (MDMS), which has been designed and built in our laboratory. The MDMS is used to capture the simulated target satellites. The objective is to evaluate the performance of the predictive controller for the capturing task and to investigate the need and feasibility of incorporating constraints into the controller. Offline solutions to multi parametric quadratic programming (mp-QP) problems are used to create a lookup table so that constrained optimal control decisions can be made in real time. Moreover, a suboptimal formulation of the mp-QP problem has been used to reduce the size of the online lookup table and to mitigate any numerical problems. The results show that when the satellite motion is predicted, the tracking performance is improved. Furthermore, when the physical constraints of the system are formulated into the optimization, the controller becomes aware of its own limitations and the approach toward the satellite is improved by eliminating the possible overshooting of the target