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A laser seeker is an important element in missile guidance and control systems, responsible for target detection and tracking. Its control is, however, a challenging problem due to complex dynamics and various acting disturbances. Hence, the purpose of this study is to propose a systematic design, tuning, analysis and performance verification of a nonlinear active disturbance rejection control (ADRC) algorithm for the specific case of the laser seeker system.

The proposed systematic approach of nonlinear ADRC application to the laser seeker system consists of the following steps. The complex laser seeker control problem is first expressed as a regulation problem. Then, a nonlinear extended state observer (ESO) with varying gains is used to improve the performance of a conventionally used linear ESO (LESO), which enables better control quality in both transient and steady-state periods. In the next step, a systematic observer tuning, based on a detailed analysis of the system disturbances, is proposed. The stability of the overall control system is then verified using a describing function method. Next, the implementation of the NESO-based ADRC solution is realized in a fixed-point format using MATLAB/Simulink and Xilinx System Generator. Finally, the considered laser seeker control system is implemented in discrete form and comprehensively tested through hardware-in-the-loop (HIL) co-simulation.

Through the conducted comparative study of LESO-based and NESO-based ADRC algorithms for the laser seeker system, the advantages of the proposed nonlinear scheme are shown. It is concluded that the NESO-based ADRC scheme for the laser seeker system (with appropriate parameters tuning methodology) provides better control performance in both transient and steady-state periods. The conducted multicriteria study validates the efficacy of the proposed systematic approach of applying nonlinear ADRC to laser seeker systems.

In practice, the obtained results imply that the laser seeker system, governed by the studied nonlinear version of the ADRC algorithm, could potentially detect and track targets faster and more accurately than the system based on the common linear ADRC algorithm. In addition, the article presents the step-by-step procedure for the design, field programmable gate array (FPGA) implementation and HIL-based co-simulation of the proposed nonlinear controller, which can be used by control practitioners as one of the last validation stages before experimental tests on a real guidance system.

The main contribution of this work is the systematic procedure of applying the ADRC scheme with NESO for the specific case of the laser seeker system. It includes its design, tuning, analysis and performance verification (with simulation and FPGA hardware). The novelty of the work is also the combination and practical realization of known theoretical elements (NESO structure, NESO parameter tuning, ADRC closed-loop stability analysis) in the specific case of the laser seeker system. The results of the conducted applied research increase the current state of the art related to robust control of laser seeker systems working in disturbed and uncertain conditions.

APPLIED Technology, Middle East and European marketing and technical support representative of PF Industries Inc, will exhibit ground support equipment supplied to airlines worldwide.

Aeronautical & General Instruments Ltd, will exhibit their R 128 recording cameras, designed to photograph the information displayed on the cathode ray tube of an aircraft's reconnaissance radar.

AEM will be exhibiting in Hall 4, Stand G1. The exhibit will illustrate AEM's comprehensive range of accessory repair and overhaul services for electrical, hydraulic, avionic and safety equipment. Farnborough will also be used as the official launch of AEM's Boeing 737 Landing Gear Total Support Pro‐gramme, which encompasses a complete exchange and overhaul service. Copies of Aviation Accessory News will be available on the stand.

The SBAC Show, now held bi‐annually, at Farnborough will take place from September 1st to the 7th, and the indications are that it will be bigger than ever. To this end new exhibition arrangements have been made and we hope to report further on these in subsequent issues.

Adwest Group Limited Stand s.P.40. Companies exhibiting:

Airscrew Howden Ltd will feature various axial flow, mixed and centrifugal flow fans which can be adapted for cabin air recirculation, engine and rotor box cooling, wheel brake cooling, face mask ventilation, with other types for aircraft applications. The fans are available for ac or dc supply or, alternatively, for quill shaft or belt drive.

Accles & Pollock Ltd. of Oldbury, Worcestershire, a TI Steel Tube Division company, will be exhibiting a comprehensive range of precision steel tube and tubular products, including plain, annularly convoluted and thin wall tube, at Farnborough.

Messerschmitt‐Bölkow‐Blohm, Germany's biggest aerospace company, is presenting sections of its wide range activities at Farnborough. As befits its corporate policy — typical examples may also be seen on the stands and in the outdoor displays of the companies in whose programmes MBB has an essential share in its capacity as shareholder or partner:

SECURITY is so much more complex when it concerns a number of countries that even to date, information released about the Multi Role Combat Aircraft is severely limited. The main areas where collaboration is well advanced comprises the development and manufacture of the integrated drive generators which is a joint undertaking by Lucas Aerospace and Siemens AG, the auxiliary power unit, again by Lucas Aerospace but this time in conjunction with Microtecnica and Kloeckner‐Humboldt‐Deutz. A joint team of Nord Micro, Hawker Siddeley Dynamics and Microtecnica are designing, developing and manufacturing the air intake control system. The spoiler actuator is by Oleodinamica Magnaghi in association with Fairey Hydraulics; the oxygen system involves Normalair‐Garrett, Draegerwerk AG of Germany and OMI of Italy. The landing gear and associated hydraulics development is headed by the Dowty Group with a large share of development and production phase work being undertaken by notably Oleodinamica Magnaghi and Nardi of Italy and Liebherr of Germany will also participate. Companies undertaking detail manufacture and subassembly of selected portions of the wing section are the Italian companies Rinaldo Piaggio, Aeronautica Macchi, Siai Marchetti, Saca, Aerfer and Aeronavali Venezia.