Description: This proposal is for the development a fault detection and isolation (FDI) algorithm for a formation of satellites but processed at a ground station. The algorithm will be capable of operating when measurement data is available on an intermittent basis. An FDI algorithm for faults in the three translational and rotational modes of 4 satellites flying in formation in a highly elliptical orbit will be designed during the Phase 1 effort. The satellites will carry a limited suite of instruments, just sufficient to determine faults in the three translational and rotational modes and include a GPS receiver. Communication with a ground station will only be available near perigee. The measurement data is not stored and transmitted in bursts, so these communication blackouts represent a break in the time history of measurements. The proposed development will mitigate these breaks so that fault detection and isolation can be performed faster than in a simple, cyclical restart implementation. Furthermore, their elliptical orbit will carry the satellites beyond the GPS constellation. The proposed development will account for the loss of GPS coverage as well investigate ways of extending the useful of GPS (when signals are weak) for fault detection and isolation.

Benefits: A NASA certified system would have potential market to Department of Defense and commercial users who want to implement a fault detection and isolation system on an existing system. The product of the proposed research effort allows for the implementation of FDI from a remote location while taking into account the limitations of communication that may exist. The goal would be to seek out partnerships with companies to find applications for our system on their products which may already be deployed. Our product has the benefit of not requiring upgrades to the system that is being monitored. Rather, the improvement is made at a base station and, potentially, for multiple systems. For example, CubeSat satellites may benefit from this implementation of FDI without having to tax its already limited processing resources.

This type of system may be implemented on NASA flight test experiments for formations of satellites where resources restrictions limit the implementation of code not associated with flight control and the payload. Furthermore, this system can be readily applied to existing missions to enhance reliability and safety without having to change the on-board flight software. For example, the proposed FDI algorithm can be applied directly to the Magnetospheric Multiscale (MMS) satellites to verify thruster and accelerometer performance. The MMS satellites are resource-limited and cannot communicate with each other. Similarly constrained missions can benefit from the product of this proposed effort.