Uppsala University Department of Information Technology

Technical Report 2004-008

An Integrating Linearization Method for Static Input Nonlinearities

Pär Samuelsson and Bengt Carlsson

March 2004

This report considers a method for linearization of models containing static input nonlinearities in series with a linear model, so called Hammerstein models. The method is based on exact linearization via internal feedback and is performed by differentiating the nonlinearity with respect to the input signal. Using this approach, an integration is added in the loop gain of the linearized system via the internal feedback. Standard linear design strategies can be used in order to construct a control law for the resulting integrating linearized system. The method presented here should be seen as an alternative to the standard method that utilizes the inverse of the static nonlinearity. Particularly, in cases when analytic inversion is difficult, the presented method provides an attractive alternative. An extension of the method where the static nonlinearity is fed by both the input and output signals is also presented and illustrated with some simulation results.

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