Robust tracking with cooperative parallel controllers

This paper deals with robust tracking of time varying signals when there are abrupt, sudden random changes in the system parameters, the sensor gains or the transducers. Robustness of the filter is achieved by introducing a parallel cooperative controller and utilizing a new nonlinear gain-tuning algorithm for the adjusting jump parameters. By the aid of this algorithm, the filter remains stable even if the varying parameters, having unknown statistics, are outside of the original linear stability region of the nominal values of these parameters, i.e., momentarily, the eigenvalues of the discrete-time linear model of the system are outside of the unit circle. To limit the noise of the output, the gain-tuning process is activated only if the differences between the two parallel outputs of the filter are over a specified threshold.