Subsystem decomposition for distributed state estimation of nonlinear systems

In this work, we investigate the subsystem decomposition problem for distributed state estimation of nonlinear systems. A systematic procedure for subsystem decomposition for distributed state estimation is proposed. Key steps in the procedure include observability test of the entire system, observable states identification for each output measurement, relative degree analysis and sensitivity analysis between measured outputs and states. A few examples used to illustrate the methods used in different steps and the entire procedure demonstrate the effectiveness and applicability of the proposed methods/procedure.