Description: This proposal is for the development of a dynamic fault detection filter for a formation of satellites operating in a highly nonlinear dynamic environment but processed at a ground station where measurement data may be available on an intermittent basis. A previous SBIR study demonstrates that nonlinearities have an adverse effect on a linear dynamic filter's ability to accurately declare faults. Thus, a fault detection filter capable of effectively accounting for nonlinear dynamics and measurement data interruptions is required. During the proposed Phase I effort, such filters will be designed for faults in the three translational modes of 4 satellites flying in formation near a highly elliptical orbit. The satellites will carry a limited suite of instruments, just sufficient to determine faults in the three translational modes and include a GPS receiver. Furthermore, communication with a ground station will only be available near perigee and the measurement data will be transmitted in bursts, which will introduce planned and unplanned communication blackouts that represent breaks in the time history of measurements. The proposed development will produce a fault detection and isolation algorithm that can mitigate these breaks and perform faster than a simple, cyclical restart implementation.

Benefits: 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 or hardware. For example, the proposed FDI algorithm can be applied to the Magnetospheric Multiscale (MMS) satellites to verify thruster and accelerometer performance even though the MMS satellites are resource-limited and cannot communicate with each other. Similarly constrained missions can benefit from the product of this proposed effort.

A NASA certified system would have potential markets within the Department of Defense and commercial users who want to implement dynamic fault detection and isolation 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.