Combine harvester header height control via robust feedback linearization

Studies have shown that feedback linearization can provide an effective controller for many types of nonlinear systems. It is known, however, that these controllers are not robust, in particular to model uncertainties. Recent work on sensitivity theory has shown that it can provide the least conservative design for robust feedback linearization. This is achieved by adjusting the control input to minimize the sensitivity. This work in this article develops the robust feedback linearization (RFL) methodology further by extending it to a new class of non-linear systems. The RFL methodology is applied to the combine harvester header height example and derivation of the controller is shown. It is tested over a variety of simulated conditions and is compared to the current industry standard, the PID controller. The results show that the RFL controller greatly improves header height tracking with less input power and is robust to uncertainties the bulk modulus.