Robust flight control method for nonlinear non-minimum phase aircraft

Abstract

The invention provides a robust flight control method of a nonlinear non-minimum phase aircraft. According to the method, the non-minimum phase problem is avoided through the design of an auxiliary observer, and a classical linear robust control method is well expanded to a nonlinear system based on a compensation idea, so that the flight control of the nonlinear non-minimum phase aircraft is realized. The method is simple, effective and high in flexibility and safety. The method comprises the following two steps of: 1, a model transformation stage: decomposing an original nonlinear system into two subsystems based on an additive state decomposition theory; and 2, a controller design stage: respectively designing controllers for the two subsystems, and combining with an auxiliary observer to obtain a final robust flight controller.

Description

technical field [0001] The invention belongs to the technical field of flight control, in particular to a robust flight control method for a nonlinear non-minimum phase aircraft. Background technique [0002] A nonlinear system is non-minimum phase if its internal or zero dynamics are unstable. Many aircraft can be modeled as nonlinear non-minimum phase systems, such as hypersonic vehicles, conventional fixed-wing aircraft, and vertical take-off and landing aircraft. For the aircraft, the non-minimum phase characteristics of the system are determined by its dynamic characteristics. [0003] For most aircraft, the trajectory maneuver is based on the adjustment of the aircraft attitude angle. The deflection of the control surface will not only produce a rotational moment that changes the attitude of the aircraft, but also a force that changes the flight path of the aircraft, which is the parasitic force of the rotational moment. It is this coupling of forces and moments tha...

AI Technical Summary

Problems solved by technology

However, for nonlinear systems with unstable zero dynamics, the non-minimum phase property limits the direct application of these techniques

Also, zero dynamics are not changed by feedback, so non-minimum-phase systems are much more difficult to control than minimum-phase systems

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