• Title/Summary/Keyword: vehicle component

Search Result 686, Processing Time 0.028 seconds

Underwater Navigation of AUVs Using Uncorrelated Measurement Error Model of USBL

  • Lee, Pan-Mook;Park, Jin-Yeong;Baek, Hyuk;Kim, Sea-Moon;Jun, Bong-Huan;Kim, Ho-Sung;Lee, Phil-Yeob
    • Journal of Ocean Engineering and Technology
    • /
    • v.36 no.5
    • /
    • pp.340-352
    • /
    • 2022
  • This article presents a modeling method for the uncorrelated measurement error of the ultra-short baseline (USBL) acoustic positioning system for aiding navigation of underwater vehicles. The Mahalanobis distance (MD) and principal component analysis are applied to decorrelate the errors of USBL measurements, which are correlated in the x- and y-directions and vary according to the relative direction and distance between a reference station and the underwater vehicles. The proposed method can decouple the radial-direction error and angular direction error from each USBL measurement, where the former and latter are independent and dependent, respectively, of the distance between the reference station and the vehicle. With the decorrelation of the USBL errors along the trajectory of the vehicles in every time step, the proposed method can reduce the threshold of the outlier decision level. To demonstrate the effectiveness of the proposed method, simulation studies were performed with motion data obtained from a field experiment involving an autonomous underwater vehicle and USBL signals generated numerically by matching the specifications of a specific USBL with the data of a global positioning system. The simulations indicated that the navigation system is more robust in rejecting outliers of the USBL measurements than conventional ones. In addition, it was shown that the erroneous estimation of the navigation system after a long USBL blackout can converge to the true states using the MD of the USBL measurements. The navigation systems using the uncorrelated error model of the USBL, therefore, can effectively eliminate USBL outliers without loss of uncontaminated signals.

A Fusion Algorithm of Pure Pursuit and Velocity Planning to Improve the Path Following Performance of Differential Driven Robots in Unstructured Environments (차동 구동형 로봇의 비정형 환경 주행 경로 추종 성능 향상을 위한 Pure pursuit와 속도 계획의 융합 알고리즘)

  • Bongsang Kim;Kyuho Lee;Seungbeom Baek;Seonghee Lee;Heechang Moon
    • The Journal of Korea Robotics Society
    • /
    • v.18 no.3
    • /
    • pp.251-259
    • /
    • 2023
  • In the path traveling of differential-drive robots, the steering controller plays an important role in determining the path-following performance. When a robot with a pure-pursuit algorithm is used to continuously drive a right-angled driving path in an unstructured environment without turning in place, the robot cannot accurately follow the right-angled path and stops driving due to the ground and motor load caused by turning. In the case of pure-pursuit, only the current robot position and the steering angle to the current target path point are generated, and the steering component does not reflect the speed plan, which requires improvement for precise path following. In this study, we propose a driving algorithm for differentially driven robots that enables precise path following by planning the driving speed using the radius of curvature and fusing the planned speed with the steering angle of the existing pure-pursuit controller, similar to the Model Predict Control control that reflects speed planning. When speed planning is applied, the robot slows down before entering a right-angle path and returns to the input speed when leaving the right-angle path. The pure-pursuit controller then fuses the steering angle calculated at each path point with the accelerated and decelerated velocity to achieve more precise following of the orthogonal path.

Introduction to Quality Management System of Rocket Fuel at NARO Space Center (나로우주센터의 발사체 연료유 품질관리 과정 소개)

  • Kim Seong-Lyong
    • Journal of Aerospace System Engineering
    • /
    • v.18 no.1
    • /
    • pp.79-87
    • /
    • 2024
  • The Korean launch vehicle (KSLV-II) has used commercial aviation jet fuel, Jet A-1. Fuel specifications were introduced from Jet A-1 specifications. However, specifications and inspection methods of moisture and particulate matters were changed digitally for convenience and accuracy. To control fuel quality, a fuel management system was established to determine suitability by inspecting it at each stage of warehousing, storage, and application. An analysis room was then established at the Naro Space Center. The possibility of fuel mixing was blocked by warehousing inspection. Long-term component changes were then observed by storage inspection. Finally, suitability of the engine test or the launch vehicle test was determined through application inspection. Long-term analysis verified that the space center's fuel oil storage method was appropriate and that the quality management system was able to handle hundreds of engine tests and several flight tests.

A Study on Fault Detection of Main Component for Smart UAV Propulsion system (스마트 무인기 추진시스템의 주요 구성품 손상 탐지에 관한 연구)

  • Kong, Chang-Duk;Kim, Ju-Il;Ki, Ja-Young;Kho, Seong-Hee;Choe, In-Soo;Lee, Chang-Ho
    • Proceedings of the Korean Society of Propulsion Engineers Conference
    • /
    • 2006.11a
    • /
    • pp.281-284
    • /
    • 2006
  • An intelligent performance diagnostic program using the Neural Network was proposed for PW206C turboshaft engine. It was selected as a power plant for the tilt rotor type Smart UAV (Unmanned Aerial Vehicle) which has been developed by KARI (Korea Aerospace Research Institute). The measurement parameters of Smart UAV propulsion system are gas generator rotational speed, power turbine rotational speed, exhaust gas temperature and torque. But two measurement such as compressor exit pressure and compressor turbine exit temperature were added because they were difficult each component diagnostics using the default measurement parameter. The performance parameters for the estimate of component performance degradation degree are flow capacities and efficiencies for compressor, compressor turbine and power turbine. Database for network learning and test was constructed using a gas turbine performance simulation program. From application results for diagnostics of the PW206C turboshaft engine using the learned networks, it was confirmed that the proposed diagnostics could detect well the single fault types such as compressor fouling and compressor turbine erosion.

  • PDF

Study on the Application of the Electric Drive System of Fuel Pump for Diesel Engine of Commercial Vehicle using HILS (HILS기반 상용차 디젤엔진용 연료펌프의 전기구동 시스템 적용에 관한 연구)

  • Ko, Youngjin
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.22 no.2
    • /
    • pp.166-174
    • /
    • 2014
  • Fuel injection pressure has steadily increased in diesel engines for the purpose of improving fuel efficiency and cleaning exhaust gas, but it has now reached a point, where the cost for higher pressure does not warrant additional gains. Common rail systems on modern diesel engines have fuel pumps that are mechanically driven by crankshaft. The pumps actually house two pumping module inside: a low pressure pump component and a high pressure pump component. Part of the fuel compressed by the low pressure component returns to the tank in the process of maintaining the pressure in the common rail. Since the returning fuel represents pumping loss, fuel economy improves if the returned fuel can be eliminated by using a properly controled electrical fuel pump. As the first step in developing an electrical fuel pump the fuel supply system on a 6 liter diesel engine was modeled with AMESim to analyze the workload and the fuel feed rate of the injection pump, and the results served as basis for selecting a suitable servo motor and a reducer to drive the pump. A motor controller was built using a DSP and a program which controls the common rail pressure using a proportional control method based on the target fuel pressure information from the engine ECU. A test rig to evaluate performance of the fuel pump is implemented and used to show that the newly developed electrically driven fuel pump can satisfy the fuel flow demand of the engine under various operating conditions when the rotational speed of the pump is adequately controlled.

Study on Friction Characteristic of Sintered Friction Component for Synchronizer-Ring of Diesel Vehicle (디젤차량 싱크로나이저링을 위한 소결마찰재 개발 및 접합특성 평가)

  • Song, Joon Hyuk;Kim, Eun Sung;Kim, Kyung-Jae;Oh, Je-Ha;Yang, Sung Mo;Kang, Shin Jae
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.37 no.3
    • /
    • pp.373-378
    • /
    • 2013
  • The speed change performance of transmissions has become a serious issue because of the increase in the inertia moment that has accompanied increases in engine output and transmission size. Therefore, it is necessary to develop better wear resistant friction materials. In this study, an appropriate sintered friction component for the synchronizer ring of a diesel manual transmission was developed, and its bonding characteristics were analyzed. That is, a process for bonding an Fe-based base material and Cu-based sintered friction material was developed. BSE and EDX analyses of this bonding layer were conducted, along with a shear strength test, to determine the bonding characteristics.

Intercooler for Multi-stage Turbocharger Design and Analysis of the Hydrogen Reciprocating Engine for HALE UAV (고고도 장기체공 무인기용 수소 왕복 엔진의 다단터보차저용 인터쿨러 설계 및 해석)

  • Lee, Yang Ji;Rhee, Dong Ho;Kang, Young Seok;Lim, Byoeung Jun
    • The KSFM Journal of Fluid Machinery
    • /
    • v.20 no.1
    • /
    • pp.65-73
    • /
    • 2017
  • Intercoolers for multi-stage turbocharger of the hydrogen reciprocating engine for HALE UAV are installed for reducing the charged air inlet temperature of the engine. The intercooler is air to air, cross flow, plate-fin type and the fin configuration is offset-strip fin which is referenced from the heat exchanger of the ERAST. Most of HALE UAV's cruising altitude is 60,000 ft and the density of air for this altitude is very low compared to sea level. Therefore the required heat transfer area for the HALE UAV is about three-times bigger than the sea level. Consequently, it is essential to design to meet the required efficiency of intercooler in the range of not excessively growing the weight of the heat exchanger. The quasi-one dimensional heat transfer design/analysis for satisfying the requirement of the engine are written in this paper. The numerical analyses for estimating the coolant flow rate of the engine bay and pressure loss in the header and core are also summarized.

A Study on Compressor Map Identification using Artificial Intelligent Technique and Performance Deck Data (인공지능 및 성능덱 데이터를 이용한 압축기 성능도 식별에 관한 연구)

  • Ki Ja-Young;Kong Chang-Duck;Lee Chang-Ho
    • Journal of the Korean Society of Propulsion Engineers
    • /
    • v.9 no.4
    • /
    • pp.81-88
    • /
    • 2005
  • In order to estimate the gas turbine engine performance precisely, the component maps containing their own performance characteristics should be needed. In this study a component map generation method which may identify compressor map conversely from a performance deck provided by engine manufacturer using genetic algorithms was newly proposed. As a demonstration example for this study, the PW 206C turbo shaft engine for the tilt rotor type Smart UAV(Unmanned Aerial Vehicle). In order to verify the proposed method, steady-state performance analysis results using the newly generated compressor map was compared with them performed by EEPP(Estimated Engine Performance Program) deck provided by engine manufacturer. And also the performance results using the identified maps were compared with them using the traditional scaling method. When the performance analysis is performed at far away operation conditions from the design point, in case of use of e component map by the traditional scaling method, the error of the performance analysis results is greatly increasing. In the other hand, if in case of use of the compressor map generated by the proposed GAs scheme, the performance analysis results are closely met with those by the performance deck, EEPP.

Lateral Load Distribution Estimation of a PSC Girder Bridge from Dynamic Loading Test (동적재하시험을 통한 PSC 거더교의 횡분배 측정)

  • Kim, Sung-Wan;Cheung, Jin-Hwan;Kim, Seong-Do;Park, Jae-Bong;Lee, Myoung-Jin
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.21 no.3
    • /
    • pp.60-68
    • /
    • 2017
  • Since the bridge is the main facility of the road that is the core of the civil infrastructure, the bridge is constructed to ensure stability and serviceability during the traffic use. In order to secure the safety of bridges, evaluating the integrity of bridges at present is an important task in the maintenance work of bridges. In general, to evaluate the load carrying capacity of bridges, it is possible to confirm the superimposed behavior and symmetric behavior of bridges by estimating the lateral load distribution factor of the bridges through vehicle loading tests. However, in order to measure the lateral load distribution factor of a commonly used bridge, a static loading test is performed. There is a difficulty in traffic control. Therefore, in this study, the static displacement component of the bridge measured in the dynamic loading test and the ambient vibration test was extracted by using empirical mode decomposition technique. The lateral load distribution was estimated using the extracted static displacement component and compared with the lateral load distribution factor measured in the static loading test.

Anti-Fatigue Properties of Cultivated Wild Ginseng Distilled Extract and Its Active Component Panaxydol in Rats

  • Shin, Il-Soo;Kim, Do-Hee;Jang, Eun Young;Kim, Hee Young;Yoo, Hwa-Seung
    • Journal of Pharmacopuncture
    • /
    • v.22 no.2
    • /
    • pp.68-74
    • /
    • 2019
  • Objectives: Cultivated wild ginseng (cWG), called SanYangSanSam, has been used clinically in patients with chronic fatigue in Korea. Little is known about effects of the ginseng distilled (volatile) components produced during evaporizaiton. Recently, we first identified one major component from cWG distilled extract, panaxydol, by using mass spectrometry. However, functional properties of cWG distilled extract and panaxydol remains elusive. Therefore, the present study evaluated the effect of cWG distilled extract or panaxydol on exercise-induced fatigue in rats. Methods: Fatigue was induced by forced swimming and the immobility time was analyzed in male Sprague-Dawley rats. The animals received intraperitoneally either vehicle, cWG distilled extract, or panaxydol 10 min prior to beginning of the forced swimming test (FST) once daily for 5 days. After the FST on day 5, we also analyzed fatigue-related biochemical levels including blood urea nitrogen (BUN), lactate acid (LAC), and lactate dehydrogenase (LDH) in serum and levels of glycogen in liver and soleus muscle. Results: The forced swimming time in cWG distilled extract (0.6 mL/kg)-treated group was significantly longer than that of control group on day 4 and 5. Panaxydol (0.1 and 0.25 mg/kg)-treated groups showed significantly enhanced performance in the forced swimming, compared to control. In addition, a significant decrease in serum LDH level was found in panaxydol-treated group, while there were no alternations in levels of serum BUN and LAC and glycogen in liver or soleus muscle. Conclusion: The present study demonstrated cWG distilled extract and its active component panaxydol have a function of anti-fatigue.