Nonlinear Estimation of Rigid Body Inertial Parameters

Nonlinear estimation of inertial parameters (mass, center of mass and the inertia matrix entries) of a rigid body with six degrees of freedom is a challenging problem given the analytical complexity of the nonlinear system dynamics. Using Lie algebraic observability methods, we show that an appropriate, nonzero net force is needed to be able to estimate all the parameters. Using the parameters of an airliner in 2D we then compute the empirical observability Gramian for three excitation (input) profiles to study the effects on the system observability. Finally, we show that the performance of an extended Kalman filter is consistent with the numerical observability analysis results.