Experiments on the payload-adaptation of a flexible one-link manipulation with unknown payload

Experiments on the payload adaptation of a flexible one-link manipulator with an unknown payload on the tip are described. Off line and online system identification schemes are implemented and compared. Three robust online indentification schemes, namely, the standard recursive-least-squares method, a least-squares method with known information lumped, and an average modified gradient method, are implemented, and their performance is evaluated based on the models obtained from off line identification. Through the use of an eight-order Butterworth low-pass filter, the effect of unmodeled dynamics on the online identification schemes is investigated. It is found, through experiments, that the least-squares-based methods are sensitive to unmodeled dynamics, while the average gradient method shows significant improvement in counteracting the unmodeled dynamics