Nonlinear geometric multivariable control for unmanned aircraft flight system

Purpose Due to the important role of unmanned aircraft in military and human’s normal practical application, this paper aims to extend the interesting research on unmanned aircraft flight controller design from the point of nonlinear multivariable case and differential geometry theory. More specifically, firstly one varying thrust force is added in the bottom of unmanned aircraft, then after a complete force analysis with the physical principle, a nonlinear dynamic model for unmanned aircraft flight system is constructed with multi-variables, such as multi inputs, multi states and multi outputs. Secondly, based on this established nonlinear multivariable system, nonlinear differential geometry theory is applied to design those multi inputs without any linearization process. Thirdly, further disturbance rejection is achieved under the framework of Lie derivative from differential geometry theory. Finally, to achieve the combination of theory and practice, a real-world platform about unmanned aircraft flight control system is established to prove the efficiency of our applied nonlinear geometry multivariable control through some simulations. Design/methodology/approach Firstly, consider one practical unmanned aircraft with one additional varying thrust force, its physical principle is analyzed to generate one corresponding nonlinear multivariable dynamic model. Secondly, combinations with nonlinear differential geometry and multivariable theory are proposed to design the nonlinear flight controller. Thirdly, Lie derivative from differential geometry is used to reject the external disturbance. Findings From the introduction and knowledge, control idea exists everywhere in our normal life. As unmanned aircraft has become increasingly important during modern war as one tactical weapon, so we think how to design one nonlinear controller for nonlinear multivariable unmanned aircraft flight system, while rejecting the external disturbance. Specifically, we give the detailed theoretic derivation and practical platform, i.e. applying the existing nonlinear geometric multivariable control in designing nonlinear unmanned aircraft controller. Originality/value To the best knowledge of the authors, mathematical theory and practical application are separated with each other. This paper is to break this wall and combine them together, although nonlinear differential geometry is very mature, but few for unmanned aircraft control system. Rough speaking, our paper establishes a new nonlinear dynamical system for unmanned aircraft with an additional varying thrust force, and designs a nonlinear controller from the point of nonlinear differential geometry, so the mission is to verify the existed nonlinear differential geometry theory benefit for unmanned aircraft flight control system truly.