Frequency Response Function Measurements of Multivariable Systems via Local Rational Modeling

Experimental Comparison of Methods for Multivariable Frequency Response Function Estimation

Nonparametric estimation methods for the multivariable frequency response function are experimentally evaluated using closed-loop data from an industrial robot. Three classical estimators (H1, joint input-output, arithmetic mean) and two estimators based on nonlinear averaging techniques (harmonic mean, geometric/logarithmic mean) are considered. The estimators based on nonlinear averaging give...

Parameter Estimation from Frequency Response Measurements Using Rational Fraction Polynomials

This is a new formulation which overcomes many of the numerical analysis problems associated with an old least squared error parameter estimation technique. Overcoming these problems has made this technique feasible for implementation on mini-computer based measurement systems. This technique is not only useful in modal analysis applications for identifying the modal parameters of structures, b...

Non-parametric frequency response estimation using a local rational model

A review of the relationship between the frequency response function of linear system and the DFT of the input and output signals show that the output DFT is a sum of two terms. The first term contain the FRF multiplied with the input DFT and the second term capture the effect when the system is not operating in a periodic fashion. The utilization of these two terms when performing non-parametr...

Impact of nonlinear friction on frequency response function measurements

This paper discusses the impact of nonlinear friction on frequency response function (FRF) measurements of mechanical systems with nonlinear friction. Having an idea of the level of nonlinear distortion is valuable information for robust linear control design: it allows to estimate the level of accuracy of a linear approximation of the system under consideration. The impact of nonlinear distort...

Analysis of windowing/leakage effects in frequency response function measurements