Fault estimation using relative information for a formation of dynamical systems

In this paper, a novel fault estimation method is proposed for a `system of systems´ formed by a collection of agents performing a shared task using relative sensing information communicated over an information network. The proposed scheme is based on sliding mode observers and the faults are reconstructed by appropriate processing of the equivalent output error injection signal that is required to maintain sliding. Since the system with respect to relative sensing measurements is not observable, an observable subspace is obtained by appropriate transformations and suitable scaling of the inputs and outputs of the actual system. In the new coordinates, with appropriate scaling, the design of decoupled sliding mode observers depends entirely on the individual node level dynamics of the network and exploits an already available design philosophy. The fault estimation framework proposed in this paper is applied to a large network of double integrator systems to demonstrate its efficacy.