On-line frequency and damping estimation in a single-link flexible manipulator based on algebraic identification

The problem of estimating the defining parameters in a sinusoidal signal corrupted by noise is very important in the vibration analysis of flexible structures. Such estimations can be used in Health Monitoring or in adaptive control applications. Usually, pure sinusoidal models are used in order to represent the mechanical vibration. The main problem of these models is they do not consider the damping phenomenon of the flexible structures. In this work, an algebraic approach is used for the fast and reliable, on line, identification of the natural frequency and its damping coefficient of a flexible-link manipulator. This method uses an exponential damping sinusoidal model in combination with the algebraic derivative method for parameter identification. The computations are performed in a time interval inferior to the first full cycle of the measured vibration signal. A single-link flexible manipulator is used to verify the estimator performance.