Abstract
The Force-State-Mapping (FSM) technique is an important method to identify the properties of the non-linear joint. The FSM can be used in the time domain and frequency domain. The main objective of this work was to discuss the problems of FSM proposed by Kim and Park【7】.When the mathematical model of the joint is not known in advance, different models of the joint can be assumed. However, it was investigated that when the assumed model does not include all the terms of the exact joint model, the result identified will be data dependency. To avoid data dependency, a method was suggested to update joint model by using the noise contaminated data. The result of model updating showed that all the terms of the exact model can be found and all the surplus terms can be taken off when the exact joint model is a polynomial function of the joint displacement and velocity. However, when the exact joint model includes a friction damping element, the method of model updating can not work successfully. Consequently, more effort should be done for the identification of the joint parameters.