Nonlinear Model Based Estimation of Rigid-Body Motion Via an Indirect Measurement of an Elastic Appendage

In this paper we develop and implement a nonlinear model based procedure for estimation of rigid body motion via an indirect measurement of an elastic appendage. We demonstrate the procedure by motion analysis of a compound planar pendulum from indirect optoelectronic measurements of markers attached to an elastic appendage that is restrained to slide along the rigid-body length. We implement a Lagrangian approach to derive a theoretical nonlinear model that consistently incorporates the generalized forces acting on the system. Identification of the governing linear and nonlinear system parameters is obtained by analysis of frequency and damping backbone curves obtained from controlled experiments of the decoupled system elements. Comparison of an independently measured rotation angle to that obtained by the model-based estimation procedure enables evaluation of the procedure accuracy and its advantages over standard noninvasive methods.Copyright © 2007 by ASME