Identification of Nonlinear Joint Parameters with Force-state Mapping Method

Abstract

Identification of the non-linear joint parameters of the complex structure with force-state mapping in frequency domain,the number of the data required in the curve fitting can be drastically reduced compared to the time domain approach.Because the model of the joint is not known in advance,and noise affected the identification accuracy cannot be ignored,when using least square method to solve the over-determined equation,due to the inverse operation of the matrix,the noise may have great effect on the identified parameters,the equation will be ill-condition and the ill-posed problem arise from the noise effect.A novel method to identify the nonlinear joint parameters is proposed from two aspects as follow:the assumed model includes all the exact terms and some surplus term;the assumed model does not include all the exact terms and has some surplus terms.A model combining Tikhonov regularization and iterative method is suggested to update the joint model.It is found that even if the assumed model does not include all the exact terms,as long as model updated continually,meet the convergence criteria,the identification accuracy is still high.Example analysis confirms that this method has high identification accuracy.