Starting up unstable multivariable controllers safely

The problem of superimposing a multivariable controller on a running plant is considered. A simple but effective controller architecture is suggested which allows the transition from a conventional controller to a full multivariable controller to take place in a continuous way. This architecture allows for unstable controllers to be handled in a reliable way. Moreover, bandwidth properties can be tuned separately. This architecture can be extended to a tool for implementing gain scheduled controllers in the same fashion.