Linear Model Predictive Control for a planar free-floating platform: A comparison of binary input constraint formulations

Zusammenfassung (Abstract) :

This work develops a first Model Predictive Controller for ESA's 3-dof free-floating platform. The challenges of the platform are the on/off thrusters, which cannot be actuated continuously and which are subject to certain timing constraints. This work compares penalty-term, Linear Complimentarity Constraints, and classical Mixed Integer formulations in order to develop a controller that natively handles binary inputs. Furthermore, linear constraints are proposed which enforce the timing constraints. Only the Mixed Integer formulation turns out to work sufficiently. Hence, this work develops a new Mixed Integer Model Predictive Controller on the decoupled model of the platform. Feasibility analysis and simulation results show that for a short enough prediction horizon, this controller can (sub)optimally stabilize and control the system under consideration of the constraints in real-time.

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franek_ma_thesis_ASTRA_paper.pdf