• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.11
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• pp.999-1005
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• 2007

In case of an abnormal condition of control surface, the real-time estimation of aerodynamic derivatives are required for the reconfigurable control system to be flight for missions or return to the head office. The goal of this paper is to represent a technique of fault detection to the control surface as a base research to the fault tolerant control system for safety improvement of UAV. The real-time system identification for the fault detection to the control surface was applied with the recursive Fourier Transform and verified through the HILS and flight test. The failures of the control surface are detected by comparing the control derivatives in fault condition with the normal condition. As a result from the flight test, we have confirmed that the control derivatives of fault condition less than about 50% in the normal condition.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2603-2605
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• 2004

적외선 영상 시뮬레이션 시스템(IIRSS : Imaging Infrared Simulation System)은 적외선 영상 센서를 탑재한 유도무기체계의 종말 호밍 단계에서의 체계 유도조종 성능 및 기능을 시험평가하기 위한 목적으로 연구 개발되었다. 적외선 영상 시뮬레이션 시스템은 체계성능을 단계적이고 종합적인 시험평가를 위하여 표적 주위 환경에 대하여 사실적이고, 동적인 실시간 시뮬레이션 환경이 제공되어야한다. 시뮬레이터 개발에 있어서 주요 관련 기술은 지형, 지물에 대한 3차원 모델링, 대기투과효과 모델링 및 합성된 적외선 영상의 실시간 렌더링 기술 등이다. 본 논문에서는 적외선 센서 시뮬레이션의 방법으로써 HILS(Hardware-in-The-Loop Simulation)를 위한 시뮬레이터 구성, 적외선 영상 생성을 위한 도구와 절차 및 시뮬레이션 방안에 대하여 기술한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.3
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• pp.181-192
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• 2022

Active vibration control system(AVCS) for helicopter enables to control the vibration generated from the main rotor and has the superb vibration reduction performance with low weight compared passive vibration reduction device. In this paper, FxLMS algorithm-based vibration control software of the light civil helicopter tansmits the control command calculated using the signals of the tachometer and accelerometers to the circular force generator(CFG) is developed and verified. According to the RTCA DO-178C/DO-331, the vibration control software is developed through the model based design technique, and real-time operation performance is evaluated in PILS(processor in-the loop simulation) and HILS(hardware in-the loop simulation) environments. In particular, the reliability of the software is improved through the LDRA-based verification coverage in the PIL environments. In order to AVCS to light civil helicopter(LCH), the dynamic response characteristic model is obtained through the ground/flight tests. AVCS configuration which exhibits the optimal performance is determined using system optimization analysis and flight test and obtain STC certification.

• Journal of Platform Technology
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• v.10 no.4
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• pp.62-69
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• 2022

Flight control systems installed on unmanned aircraft require thorough verification from the design stage. This verification is made through the integrated flight control test environment. Typically, a debugger is used to monitor the internal state of a flight control computer in real time. Emulator with a real-time memory monitor and trace is relatively expensive. The JTAG Emulator is unable to operate in real time and has limitations that cannot be caught up with the processing speed of latest high-speed processors. In this paper, we describe the results of the development of internal monitoring software for drone flight control computer processors based on NUTTX/PIXHAWK. The results of this study show that the functions provided compared to commercial debugger are limited, but it can be sufficiently used to verify the flight control system using this system under limited budget.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.599-602
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• 2011

A propulsion controller for one-time flight vehicles should be designed robustly so that it can complete its missions even in case sensor failures. These vehicles improve their fault tolerance by back-up sensors prepared for the failure of major sensors, which raises the total cost. This paper presents the NARX model which substitutes vehicles' velocity sensors, and detects failure of sensor signals by using model based fault detection. The designed NARX model and fault detection algorithm were optimized and installed in TI's TMS320F2812 so that they were linked to HILS instruments in real-time. The designed propulsion controller made the vehicle to have better fault tolerance with fewer sensors and to complete its missions under a lot of complicated failure situations. The controller's applicability was finally confirmed by tests under the HILS environment.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.10
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• pp.805-812
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• 2013

The operational flight program(OFP) which has the functions of I/O processing with avionics, flight control logic calculation, fault diagnosis and redundancy mode is embedded in the flight control computer of Smart UAV. The OFP was developed in the environment of PowerPC 755 processor and VxWorks 5.5 real-time operating system. The OFP consists of memory access module, device I/O signal processing module and flight control logic module, and each module was designed to hierarchical structure. Memory access and signal processing modules were verified from bench test, and flight control logic module was verified from hardware-in-the-loop simulation(HILS) test, ground integration test, tethered test and flight test. This paper describes development environment, software structure, verification and management method of the OFP.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.2
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• pp.185-194
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• 2016

It is essential for generating the synthetic image to test and evaluate a guided missile system in the hardware-in-the-loop simulation. In order to make the evaluation results to be more reliable, the extent of fidelity and rendering performance of the synthetic image cannot be left ignored. There are numerous challenges to simulate the LWIR sensor signature of sea surface depending on the incident angle, especially in the maritime environment. In this paper, we investigate the key factors in determining the apparent temperature of sea surface and propose the approximate formula consisting of optical characteristics of sea surface and sky radiance. We find that the greater the incident angle increases, the larger the reflectivity of sea surface, and the greater the water vapor concentration in atmosphere increases, the larger the amount of sky radiance. On the basis of this information, we generate the virtual maritime environment in LWIR region using the SE-WORKBENCH, physically based rendering software. The margin of error is under seven percentage points.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.222-224
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• 2005

In the development of Antiskid Brake System(ABS) for a fixed-wing aircraft, the braking efficiency is the most essential parameters to evaluate the ABS, especially in slippery road conditions. The braking distance and landing distance of the aircraft depends on it. Since the ABS has been designed and implemented as a subsystem of the aircrafts, the braking performance was evaluated under dynamometer test, where the dynamometer emulates the aircraft mass. Under simulated wet road conditions, the dynamometer starts to be braked. This paper suggests practical braking efficiency calculation methods and the results and finally compares each method.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.5
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• pp.623-629
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• 2018

The acceleration and the angular velocity that include natural frequencies of a missile detected by Inertial Measurement Unit(IMU) are transmitted to the control loop of a missile. The control loop command that is calculated using above signals can cause the resonance of the missile while it flies. Hence it is common to adapt the filter and the control loop for attenuating or eliminating the undesired signals such as natural frequencies. This paper introduces the new test technique using a floating system for performance evaluation of the designed filter and the control loop prior to a flight test. The proposed scheme can check out the degradation property of vibration in the filter and the control loop, while the conventional hardware-in-the-loop simulation(HILS) scheme cannot.

• Journal of ILASS-Korea
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• v.16 no.2
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• pp.76-81
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• 2011

A fuel injection system which is operated with a real vehicle driving simulation was developed as an alternative to a vehicle test for the fuel injectors. The sensor signals that are supplied to the ECU were measured and recorded as a data file for a vehicle driven in FTP-75 mode in a chassis dynamometer. The imperative sensor signals of the throttle position, vehicle speed, engine speed, crank position, cam position, intake air flow, and cooling water and intake air temperature were reconstructed using FPGA DAQ boards and a PXI computer. The scanning results showed good agreement with the input signals that were reconstructed. The ECU HILS system operated successfully to drive six fuel injectors, which injected fuel in the same pattern as if they were mounted in the vehicle driven in FTP-75 mode. Also, the fuel injection system developed in this research shows the possibility of application in evaluating the characteristics of fuel injection rate for injectors according to properties of injected fuel with the real driving mode of vehicles.