Design of Composite Feedback and Feedforward Control Law for Aircraft Inertially Stabilized Platforms

Valerii Azarskov,Anatoly Tunik,Olha Sushchenko

doi:10.1155/2020/8853928

Valerii Azarskov, Anatoly Tunik + Show 1 more

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https://doi.org/10.1155/2020/8853928

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Abstract

The design of the control systems of the inertially stabilized platforms (ISPs) as part of airborne equipment for the majority of aircraft has its peculiarity. The presence of rate gyros in the inertial measurement unit gives the possibility to measure the rotation rate of the ISP base, which is the main disturbance interfering with the ISP accuracy. Inclusion of the feedforward disturbance gain in the control law with the simplest PI feedback significantly improves the accuracy of stabilization by the invariance theory. A combination of feedback and feedforward controllers produces a synergetic effect, thus, improving ISP accuracy. This article deals with the design of the airborne ISP control systems consisting of two stages: the parametric optimization of the PI feedback control based on composite “performance-robustness” criterion and the augmentation of the obtained system with feedforward gain. To prove the efficiency of the proposed control laws, the simulation of the ISP was undertaken. We have used a simulation of the heading-hold system of the commuter aircraft Beaver and the yaw rate output of this closed-loop system we have used as a source of the disturbance. The results of modeling proved the efficiency of the proposed design method.

Highlights

Nowadays, the inertially stabilized platforms (ISPs) are the most powerful means of stabilizing high-precision optical and optical-electronic equipment on moving vehicles
Following aforementioned the L2 − gain minimization approach and expressions (2) and (3), we proposed cost function for optimization procedure including kWdyðsÞk2 and kWdyðsÞk∞ with weighting coefficients allowing to achieve the trade-off between robustness and performance of control system
Usage of the rate gyroscopes in the inertial measurement unit (IMU) of the airborne navigation equipment gives an additional source to increase the ISP accuracy because it gives the possibility to include the feedforward disturbance gain in the control law following the main principles of the invariance theory

Summary

Introduction

The inertially stabilized platforms (ISPs) are the most powerful means of stabilizing high-precision optical and optical-electronic equipment on moving vehicles They may be used as the onboard equipment of various vehicles: aerial, terrestrial, and marine [1, 2]. Their applications for piloted aircraft and unmanned aerial vehicles (UAVs) are significantly important, as they could be the main part of commercial payload [3] as well as an important part of navigation equipment, especially for UAV landing [4], stabilization, and trajectory tracking [5]. The ISPs in aerial vehicles must be lighter, smaller, cheaper, and more power-efficient than their terrestrial and marine counterparts This imposes further restrictions on their design parameters, on the computational power of the on-board computers. Taking this fact into account, ISP control laws must be as simple as possible to implement them in the airborne computers

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