Modeling and incremental nonlinear dynamic inversion control for a highly redundant flight system

Modern aircrafts are equipped with multiple redundant non-conventional effectors to achieve capability and performance such as vertical take-off landing, supermaneuvrability, failure tolerance and high robustness, which brings about opportunities and challenges for control system design. To study potential control strategies of these configurations, a highly redundant aircraft is modelled in this paper-an “extended F-16” model based on open source NASA technical report. Compared to the normal F-16 model, the extended model features 16 independent moving effectors including two elevons, two canards, two leading edge flaps, four trailing edge flaps, two rudders and two engines each with a 2-D thrust vectoring. The resultant model is therefore highly redundant and provides a good research platform for corresponding control strategies. A baseline controller is built for this model using the technique of incremental nonlinear dynamic inversion (INDI), accompanied by a redistributed scaled pseudo inverse control allocation algorithm. Path dependency problem associated with INDI and over-actuated system is addressed by null space transition, which specifies desired input positions during steady state flight. At the end of the paper, tracking performance is presented by software simulation.