Electromagnetic Formation Flight Control Using Dynamic Programming

Electromagnetic formation flight (EMFF) is an enabling technology for a number of spacecraft mission architectures. The RINGS program will be the first time EMFF is demonstrated in a microgravity environment. Nonlinearities due to magnetic field interactions preclude linear feedback controllers from being used to control the RINGS system. Approximate dynamic programming is explored in this paper as a potential method for developing a controller. Aggregation and cost approximation methods are used to develop the cost-to-go of the system. Direct input and rollout architectures are presented for building a controller based on the cost-to-go. Aggregation and cost approximation methods are both able to produce a valid cost-to-go for the RINGS system. Both direct input and rollout control architectures are able to drive the system to the desired state given a cost-to-go, with the rollout architecture performing the same as a direct input controller. Overall, dynamic programming was successful in developing a working RINGS controller.