Stratospheric airship fixed-height flight nonlinear PID control method

Abstract

The invention discloses a stratospheric airship fixed-height flight nonlinear PID control method, which comprises the steps of: calculating a height error and an error integral through measuring the height and a vertical speed of an airship, and forming a height error PID control signal; adopting a Sigmoid function and a softening function for modulation and superposition to form a final expected pitch angle instruction signal; simulating features of a pitching channel of the airship approximately according to a mathematical model established based on a differential equation of the pitching channel of the airship; and forming a pitch angle rudder deviation control amount according to the acquired expected pitch angle instruction signal by means of a pitch angle tracking controller, observing a data curve of height variation of the airship through adjusting control parameters constantly, analyzing dynamic response to the fixed-height flight, and finally determining a group of control scheme parameters of airship fixed-height flight, so that the airship fixed-height flight has satisfactory dynamic response and steady-state response performance. The stratospheric airship fixed-height flight nonlinear PID control method has anti-saturation features not found in PID control, and reserves advantages of the PID control.

Description

technical field [0001] The invention belongs to the technical field of aircraft control, and relates to a non-linear PID control method for altitude-fixed flight of a stratospheric airship based on Sigmoid function and softening function modulation. Background technique [0002] The autonomous airship flying at the height of the stratosphere has been highly valued by scholars and engineers at home and abroad because of its broad military and civilian application prospects. The altitude control loop design of the airship is based on the well-designed inner loop attitude angle tracking loop. [0003] At present, the widely used conversion from altitude error to attitude angle expectation signal is still PID control, but the main problem of this method is that in the case of large-scale altitude control, parameter adjustment needs to be set in advance, and it is difficult to achieve a set of parameters for all expected altitudes. All fit. At the same time, it is difficult to ...

AI Technical Summary

Problems solved by technology

[0003] At present, the widely used conversion from height error to attitude angle expectation signal is still PID control, but the main problem of this method is that in the case of large-scale height control, parameter adjustment needs to be set in advance, and it is difficult to achieve a set of parameters for all desired heights. all suitable

At the same time, it is difficult to guarantee the rapidity of a high degree of control

In particular, it is difficult to ensure that the generation of the expected pitch angle signal conforms to a strong physical meaning. If the PID control parameters are selected too small, the generated expected pitch angle signal is too small and the rapidity of the height control is insufficient. If the PID control parameters are selected too If the value is large, the desired pitch angle signal obtained is too large, and it is easy to exceed the maximum limit of the pitch angle that the airship can achieve in a short time, that is, a saturation problem will occur.

Images