• Title/Summary/Keyword: Pitch Command

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Pitch Command Generation Method for Consistent Initial Trajectory of Thrust-Vector-Controlled Vehicle (추력벡터제어 비행체의 일관된 탄도 성형을 위한 피치각명령 산출 방법)

  • Lee, Yong-In;Choe, Dong-Gyun;Hwang, Tae-Won
    • Journal of the Korea Institute of Military Science and Technology
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    • v.16 no.6
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    • pp.739-744
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    • 2013
  • In this paper, we propose a method of generating pitch commands for consistent initial trajectories irrelevant to flight conditions in the initial boosting phase of a thrust-vector-controlled vehicle. After shape assumption of the pitch command profile, parameters of the profile are determined in real time in order for the summit height of the trajectory to be a desired value by deriving the summit height considering thrust performance, gravity, and other flight conditions. Computer simulation results demonstrate good performance of the proposed method.

Trajectory Optimization and Guidance for Terminal Velocity Constrained Missiles (종말 속도벡터 구속조건을 갖는 유도탄의 궤적최적화 및 유도)

  • Ryoo, Chang-Kyung;Tahk, Min-Jea;Kim, Jong-Han
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.32 no.6
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    • pp.72-80
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    • 2004
  • In this paper, the design procedure of a guidance algorithm in the boosting phase of missiles with free-flight after thrust cut-off is introduced. The purpose of the guidance is to achieve a required velocity vector at the thrust cut-off. Trajectory optimizations for four cost functions are performed to investigate implementable trajectories in the pitch plane. It is observed from the optimization results that high angle of attack maneuver in the beginning of the flight are required to satisfy the constraints. The proposed guidance algorithm consists of the pitch program to produce open-loop pitch attitude command and the yaw attitude command generator to nullify the velocity to go. The pitch program utilizes the pitch attitude histories obtained from the trajectory optimization.

Dedicated Cutback Control of a Wind Power Plant Based on the Ratio of Command Power to Available Power

  • Thapa, Khagendra;Yoon, Gihwan;Lee, Sang Ho;Suh, Yongsug;Kang, Yong Cheol
    • Journal of Electrical Engineering and Technology
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    • v.9 no.3
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    • pp.835-842
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    • 2014
  • Cutback control in a grid code is one of the functions of a wind power plant (WPP) that is required to support the system protection and frequency stability. When a cutback control command signal is delivered to the WPP from the system operator, the output of a WPP should be decreased to 20% of the rated power within 5 s. In this paper, we propose a dedicated cutback control algorithm of a WPP based on the ratio of the command power to the available power. If a cutback control signal is delivered, the algorithm determines the pitch angle for the cutback control and starts the pitch angle control. The proposed algorithm keeps the rotor speed at the speed before the start of the cutback control to quickly recover the previous output prior to the cutback control. The performance of the algorithm was validated for a 100 MW aggregated WPP based on a permanent magnet synchronous generator under various wind conditions using an EMTP-RV simulator. The results clearly shows that the proposed algorithm not only successfully reduces the output to the command power within 5 s by minimizing the fluctuation of the pitch angle, but also rapidly recovers to the output level before the cutback control.

LOS Moving Algorithm Design of Electro-Optical Targeting Pod for Joystick Command (조이스틱 명령에 따른 Electro-Optical Targeting Pod의 LOS 이동 알고리즘 설계)

  • Seo, Hyoungkyu;Park, Jaeyoung;Ahn, Jung-Hun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.10
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    • pp.1395-1400
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    • 2018
  • EO TGP(Electro-Optical Targeting Pod) is an optical tracking system which has various functions such as target tracking and image stabilization and LOS(Line of Sight) change. Especially, it is very important to move the LOS into a interest point for joystick command. When pilot move joystick in order to observe different scene, EO TGP gimbals should be operated properly. Generally, most EOTS just operate corresponding gimbal for joystick command. For example, if pilot input horizontal command in order to observe right hand screen, it just drive azimuth gimbal at any position. But in the screen, the image dosen't move in a horizontal direction because gimbal structure is Euler angle. And image rotation is occurred by elevation gimbal angle. So we need to move Pitch gimbal. So in the paper, we designed LOS moving algorithm which convert LOS command to gimbal velocity command to move LOS properly. We modeled a differential kinematic equation and then change the joystick command into velocity command of gimbals. This algorithm generate velocity command of each gimbal for same horizontal direction command. Finally, we verified performance through MATLAB/Simulink.

Feed Forward Control of the MW Wind Turbine (MW 풍력터빈의 피드포워드 제어)

  • Im, Chang-hee;Nam, Yoon-su;Kim, Jeong-gi;Choi, Han-soon
    • Journal of Wind Energy
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    • v.2 no.1
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    • pp.82-89
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    • 2011
  • his dissertation is on power control system for MW-class wind turbine. Especially, the control purpose is reduction in electrical power and rotor speed. The base control structure is power curve tracking control using variable speed variable pitch operational type. For the reduction of fluctuations, more control algorithm is needed in above rated wind conditions. Because general pitch control system is low dynamic response as compared with the wind speed change. So, this paper introduces about the pitch feed forward control to minimize fluctuations of the electrical power and rotor speed. To maintain rated electrical power, the algorithm of feed forward control adds feed forward pitch amount to the pitch command of power curve tracking control. The effectiveness of the feed forward control is verified through the simulation.

A Study on the Design and Validation of Automatic Pitch Rocker System for Altitude, Speed and Deep Stall Recovery (항공기의 고도, 속도 및 깊은 실속의 회복을 위한 자동회복장치 설계 및 검증에 관한 연구)

  • Kim, Chong-Sup
    • Journal of Institute of Control, Robotics and Systems
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    • v.15 no.2
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    • pp.240-248
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    • 2009
  • Modem version of supersonic jet fighter aircraft must have been guaranteed appropriate controllability and stability in HAoA(High Angle of Attack). The HAoA flight control law have two parts, one is control law of departure prevention and the other is control law of departure recovery support. The control laws of departure prevention for advanced jet trainer consist of HAoA limiter, roll command limiter and rudder fader. The control laws of departure recovery support are consist of yaw-rate limiter and MPO(Manual Pitch Override) mode. The guideline of pitch rocking using MPO mode is simple, but operating skill of pitch rocking is very difficult by the pilot with inexperience of departure situation. Therefore, automatic deep stall recovery system is necessary. The system called the "Automatic Pitch Rocker System" or APRS, provided a pilot initiated automatic maneuver capable of an aircraft recoveries in situations of deep stall, speed and altitude. This paper addresses the design and validation for APRS to recovery of an deep stall without manual pitch rocking by the pilot. Also, this system is designed to recovery of speed, attitude and altitude after deep stall recovery using ATCS (Automatic Thrust Control System) and autopilot. Finally, this system is verified by real-time pilot evaluation using HQS (Handling Quality Simulator).

A Study on Longitudinal Phugoid Mode Affected by Application of Nonlinear Control Laws

  • Kim, Chong-Sup;Hur, Gi-Bong;Kim, Seung-Jun
    • International Journal of Aeronautical and Space Sciences
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    • v.8 no.1
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    • pp.21-31
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    • 2007
  • Relaxed Static Stability (RSS) concept has been applied to improve aerodynamic performance of modern version supersonic jet fighter aircraft. The T-50 advanced supersonic trainer employs the RSS concept in order to improve the aerodynamic performance. And the flight control system stabilizes the unstable aircraft and provides adequate handling qualities. The T-50 longitudinal control laws employ a proportional-plus-integral type controller based on a dynamic inversion method. The longitudinal dynamic modes consist of short period with high frequency and phugoid mode with low frequency. The design goal of longitudinal control law is optimization of short period damping ratio and frequency using Lower Order Equivalent System (LOES) complying the requirement of MIL-F-8785C. This paper addresses phugoid mode characteristics such as damping ratio and natural frequency that is affected by the nonlinear control laws such as angle of attack limiter, auto pitch attitude command system and autopilot of pitch attitude hold.

Phonetic Realization of the Unstressed Weak Vowel 'Schwa' in English (영어의 비강세 약모음 schwa /e/의 음성실현)

  • Kim, Soo-Jung
    • Speech Sciences
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    • v.12 no.4
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    • pp.167-180
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    • 2005
  • The present study examines the phonetic realizations of the unstressed weak vowel /e/ in English words produced by native and Korean ESL speakers. Traditionally, the stressed elements in utterance are considered to be prominent. In this sense, the unstressed weak vowel /e/ is predicted to be shorter in length, lower in pitch and intensity than the stressed vowels. The experiment shows that native English speakers correlate the unstressed weak vowel /e/ with both shorter duration and lower pitch; Korean ESL speakers correlate it with lower pitch only. We cannot find any significant statistical difference in intensity between /e/ and the stressed vowels in both cases. This study suggests it is important to acquire and produce the correct prosodic correlates of the unstressed weak vowel /e/ for Korean ESL speakers to command more natural English intonation, since /e/ is the most common vowel in English speech and consists of the English foot rhythm along with stressed vowels.

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A Comparative Study on French Intonation between French and Korean Learners (불어 원어민과 한국인 불어 학습자의 억양 비교 연구)

  • Kim, Hyun-gi
    • Speech Sciences
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    • v.1
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    • pp.27-38
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    • 1997
  • The differences in French Intonation between French and Korean learners can be applied to French intonation education. One native French speaker and three native Korean speakers who learned French language at High school were selected for this study. The subjects spoke test phrases based on the different syntactic structures. High-Speed speech Analysis system(RILP) was used for this experiment. The different intonation curves were showed at the end of phrase and at the beginning of phrase between French and Korean learners. At the end of phrases, French intonation appeared to have increasing and decending pitch contours in the case of wh-question, exclamation and finality. However, Korean learner's intonation showed only increasing pitch contours. At the beginning of phrase, French intonation shows decending pitch contours in the case of minor continuation and command. In contrast, Korean learner's intonation appeared to have increasing pitch contours. The new intonation training system using PC can have great effect on education of French as a second language.

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Control Law Design for a Tilt-rotor Unmanned Aerial Vehicle with a Nacelle Mounted WE (Wing Extension) (체공성능 향상을 위한 확장날개 틸트로터 무인기의 제어법칙설계)

  • Kang, Young-Shin;Park, Bum-Jin;Cho, Am;Yoo, Chang-Sun
    • Journal of Institute of Control, Robotics and Systems
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    • v.20 no.11
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    • pp.1103-1111
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    • 2014
  • The results of control law design for a tilt-rotor unmanned aerial vehicle that has a nacelle mounted wing extension (WE) are presented in this paper. It consists of a control surface mixer, stability and control augmentation system (SCAS), hold mode for altitude / speed / heading, and a guidance mode for preprogram and point navigation which includes automatic take-off and landing. The conversion corridor and the control moments derivatives between the original tilt-rotor and its variant of the nacelle mounted WE were compared to show the effectiveness of the WE. The nacelle conversion of the original tilt-rotor starts when the airspeed is greater than 30 km/h but its WE variant starts at 0 km/h in order to reduce the drag caused by the high incidence angle of the WE. The stability margins of the inner loop are presented with the optimization approach. The outer loops for the hold mode are designed with trial and error methods with linear and nonlinear simulation. The main control parameter for altitude control of the helicopter mode is thrust command and it is transferred to the pitch attitude command in airplane mode. Otherwise, the control parameter for the speed of the helicopter mode is the pitch attitude command and it is transferred to the thrust command in airplane mode. Therefore the speed and altitude hold mode are coupled to each other and are engaged at the same time when an internal pilot engages any of the altitude or speed hold modes. The nonlinear simulation results of the guidance control for the preprogrammed mode and point navigation are also presented including automatic take-off and landing in order to prove the full control law.