The best linear approximation of mimo systems: simplified nonlinearity assessment using a toolbox

The aim of the paper is to introduce a case study for nonparametric nonlinear assessment using a toolbox illustrated on a small, battery-operated road vehicle. The toolbox (Simplified Analysis for Multiple Input Systems, SAMI) is based on the Best Linear Approximation framework of multiple input, multiple output systems which provides a user-friendly interpretation of the measurement data by extracting the user relevant information by splitting up the classical coherence function of the FRF measurements into noise, nonlinearity and transient parts. By the use of the proposed toolbox, a less experienced user will be able to 1) nonparametrically assess the system under test, 2) to tell whether the underlying system is linear or not, and 3) to tell how much is the gain by the use of an advanced nonlinear framework. The proposed toolbox addresses the questions related to the semi-automatic processing of MIMO measurements with respect to the whole process from the design of experiment to the nonparametric analysis of the frequency response functions. The toolbox has been tested with simulations and real-life industrial measurements.