• 한국항공우주학회지
• /
• 제33권6호
• /
• pp.51-56
• /
• 2005

본 논문에서는 GPS/INS/기압고도계를 결합한 고도 항법 알고리즘과 이를 구현한 실험 결과를 소개한다. 실험 결과의 분석을 통해 제안된 알고리즘이 무인항공기 비행제어 시스템에 적합한, 연속적이며 고도 변화에 민감한 고도 정보를 제공할 수 있음을 확인한다. 그리고 기존의 INS/기압고도계를 결합한 고도 항법 시스템의 경우 2차, 3차 구조 모두 본질적으로 상보 필터(complementary filter)의 형태를 가지기 때문에 기압고도계의 오차를 보상할 수 없는데, 제안된 알고리즘은 이러한 단점을 개선하는 구조로 구성되어 있음을 보인다.

• Journal of Positioning, Navigation, and Timing
• /
• 제10권3호
• /
• pp.189-196
• /
• 2021

In this paper, we propose techniques to correct the altitude error and heading error of 3D Pedestrian Inertial Navigation (PIN). When a PIN is used to estimate the location of a pedestrian only with an Inetrial Measurement Unit (IMU) without infrastructure, there is a problem in that the location error gradually increases due to the limitation of the observability of the filter. To solve this problem without additional sensors, we propose two techniques in this paper. First, stair walking is recognized in consideration of the altitude difference that may occur during one step. If it is recognized as stair walking, only Zero-velocity UPdaTe (ZUPT) is performed, and if it is recognized as level walking, ZUPT + Altitude Damping (AD) is performed together to correct the altitude error. Second, the straight-line movement direction is calculated through the difference of the estimated position, and the heading error is corrected by matching this information with the link information of the digital map. By applying these techniques, it is verified through real tests that accurate three-dimensional location information of pedestrians can be estimated without infrastructure.

• 제어로봇시스템학회논문지
• /
• 제14권8호
• /
• pp.727-732
• /
• 2008

In this paper, the state-space representation of generalized complimentary filter is proposed. Complementary filter has the suitable structure to merge information from sensors whose frequency regions are complementary. First, the basic concept and structure of complementary filter is introduced. And then the structure of the generalized filter and its state-space representation are proposed. The state-space representation of complementary filter is able to design the complementary filter by applying modern filtering techniques like Kalman filter and $H_{\infty}$ filter. To show the usability of the proposed state-space representation, the design of Inertial Navigation System(INS) vertical channel damping loop using Global Positioning System(GPS) is described. The proposed GPS/INS damping loop lends the structure of Baro/INS(Barometer/INS) vertical channel damping loop that is an application of complementary filter. GPS altitude error has the non-stationary statistics although GPS offers navigation information which is insensitive to time and place. Therefore, $H_{\infty}$ filtering technique is selected for adding robustness to the loop. First, the state-space representation of GPS/INS damping loop is acquired. And next the weighted $H_{\infty}$ norm proposed in order to suitably consider characteristics of sensor errors is used for getting filter gains. Simulation results show that the proposed filter provides better performance than the conventional vertical channel loop design schemes even when error statistics are unknown.

• 한국항공우주학회지
• /
• 제33권4호
• /
• pp.47-56
• /
• 2005

무인기의 INS/GPS/기압고도계 결합항법 시스템에서 수직채널감쇠루프를 사용하여 고도 오차를 보정할 때 비행 고도의 오차를 감소시키기 위해서 기압고도계의 정밀도를 향상시켜야한다. 피토정압관을 사용하여 기압 고도를 측정할 때 비행 속도와 자세 등의 변화에 따라 피토정압관 주위의 압력이 변하여 정압 오차에 의한 기압 고도의 오차를 유발한다. 정압 오차를 보정하기 위하여 풍동 시험과 CFD, 비행 시험 등의 자료를 이용하여 피토정압관 측정 압력의 변화를 분석하고 받음각과 비행 속도에 따른 압력 오차의 모델을 수립하였다. 비행 속도 변화에 의한 오차를 보정하기 위하여 피토정압관의 차압과 차압/정압 비를 사용한 두 가지 오차 모델에 대하여 압력 섭동에 대한 민감도 해석을 하였고 비행 시험에 적용하여 차압/정압 비를 사용한 모델이 고고도 비행 특성이 우수하다는 결론을 얻었다.

• International Journal of Aeronautical and Space Sciences
• /
• 제13권4호
• /
• pp.468-473
• /
• 2012

Cost is an important aspect in designing a target drone, however the poor performance of low cost IMU, GPS, and microcontrollers prevents the use of complex algorithms, such as ARS, or INS/GPS to estimate attitude angles. We propose an autopilot which uses rate gyro and GPS only for a target drone to follow a prescribed path for anti-aircraft training. The autopilot consists of an altitude hold, roll hold, and path following controller. The altitude hold controller uses vertical speed output from a GPS to improve phugoid damping. The roll hold controller feeds back yaw rate after filtering the dutch roll oscillation to estimate the roll angle. The path following controller operates as an outer loop of the altitude and roll hold controllers. A 6-DOF simulation showed that the proposed autopilot guides the target drone to follow a prescribed path well from the view point of anti-aircraft gun training.

• 한국소음진동공학회논문집
• /
• 제25권2호
• /
• pp.108-115
• /
• 2015

Electro-mechanical actuator installed on aircraft consists of a decelerator which magnifies the torque in order to rotate an axis connected with aircraft control surface, a control section which controls the motor assembly through receiving orders from cockpit and a motor assembly which rotates the decelerator. Electro-mechanical actuator controls aircraft altitude, position, landing, takeoff, etc. It is an important part of a aircraft. Aircraft maneuvering causes vibrations to electro-mechanical actuator. Vibrations may result in structural fatigue. For that reason, it is necessary to analyze the system structural safety. In order to analyze the system structural safety. It is needed reasonable finite element model and structural response stress closed to real value. In this paper, analytic model is derived by using the simplified finite element model, and damping ratio which is closely related to response stress is derived by using modal test. So, we developed analytic model in less than 10 % error rate, compared with modal test. Vibration response stress close to real value was estimated from analytic model modified with modal experimental damping ratio. Estimation method for damping ratio with empirical formula was suggested partly. Finally, It was proved that electro-mechanical actuator had reasonable structure margin of safety at environmental random $3{\sigma}$ stress during life cycle.

• International Journal of Aeronautical and Space Sciences
• /
• 제17권1호
• /
• pp.120-131
• /
• 2016

The full results of troubleshooting process related to the flight control system of a tilt-rotor type UAV in the flight tests are described. Flight tests were conducted in helicopter, conversion, and airplane modes. The vehicle was flown using automatic functions, which include speed-hold, altitude-hold, heading-hold, guidance modes, as well as automatic take-off and landing. Many unexpected problems occurred during the envelope expansion tests which were mostly under those automatic functions. The anomalies in helicopter mode include vortex ring state (VRS), long delay in the automatic take-off, and the initial overshoot in the automatic landing. In contrast, the anomalies in conversion mode are untrimmed AOS oscillation and the calibration errors of the air data sensors. The problems of low damping in rotor speed and roll rate responses are found in airplane mode. Once all of the known problems had been solved, the vehicle in airplane mode gradually reached the maximum design speed of 440km/h at the operation altitude of 3km. This paper also presents a comprehensive detailing of the control systems of the tilt-rotor unmanned air vehicle (UAV).

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2015년도 제46회 하계학술대회
• /
• pp.1379-1380
• /
• 2015

본 논문에서는 고도유지 제어기를 포함한 자율이동체의 수직 채널 안정화 루프를 제안한다. 제안된 방법은 일반적으로 널리 사용되고 있는 고전적인 수직채널 댐핑루프와 달리 고도정보와 함께 속도정보를 이용하여 궤적의 고도변화가 큰 이동체에 대하여 빠른 응답특성을 갖도록 한다. 루엔-버거(Luenberger) 관측기 구조를 이용함으로써 속도정보를 활용한 수직채널 안정화루프의 체계적 설계가 가능함을 보인다. 제안된 설계 방법에 대하여 모의실험을 통해 제안한 기법의 성능 및 유용성을 확인한다.