• Title/Summary/Keyword: Vehicle Motion Compensation Control

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A Novel Timing Control Method for Airborne SAR Motion Compensation (항공기 요동보상을 위한 SAR시스템의 타이밍 제어 기법)

  • Lee, Hyon-Ik
    • Journal of the Korea Institute of Military Science and Technology
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    • v.13 no.3
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    • pp.453-460
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    • 2010
  • For high quality image acquisition, compensating air-vehicle motion is essential for airborne SAR system. This paper describes a timing control based motion compensation method for airborne SAR system. Efficient timing control is critical for SAR system since it maintains many timing signals and timing setting for the signals should be updated frequently. This paper proposes Timing Cluster method as an efficient means for timing control of SAR system. Moreover, this paper suggests a simple and efficient method to compensate air-vehicle motion based on the Timing Cluster method. Timing Cluster method enables SAR system to control the timing in a timing noncritical way just maintaining little amount of information.

LOS(line-of-sight) Stabilization Control of OTM(on-the-move) Antenna Driven by Geared Flexible Transmission Mechanism (기어와 유연축을 갖는 구동계로 구동되는 OTM 안테나 시선의 안정화 제어)

  • Kang, Min-Sig;Yoon, Wo-Hyun;Lee, Jong-Bee
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.21 no.10
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    • pp.951-959
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    • 2011
  • In this study, an OTM(on-the-move) antenna which is mounted on ground vehicles and is used for mobile communication between vehicle and satellite while moving was addressed. Since LOS(line-of-sight) of antenna should direct satellite consistently while vehicle moving to guarantee high satellite communication quality, active antenna LOS stabilization is a core technology for OTM antenna. Stabilization of a satellite tracking antenna which consists of 2-DOF gimbals, an elevation gimbal over an azimuth gimbal, was considered in this study. In consideration of driving mechanism which consists of gear train and flexible driving shafts, a two-mass-system dynamic model coupled with vehicle motion was presented. An internal PI-control loop + outer PI-control loop structure has been suggested in order to damp the torsional vibration and stabilize control system. The classical pole-placement method was applied to design control gains. In addition, a vehicle motion compensation control beside of the feedback control loop has been suggested to improve LOS stabilization performances. The feasibility of the proposed control design was verified along with some experimental results.

Performance Enhancement of Motion Control Systems Through Friction Identification and Compensation (마찰력 식별과 보상을 통한 운동제어 시스템의 성능 개선)

  • Lee, Ho Seong;Jung, Sowon;Ryu, Seonghyun
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.19 no.6
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    • pp.1-8
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    • 2020
  • This paper proposes a method for measuring friction forces and creating a friction model for a rotary motion control system as well as an autonomous vehicle testbed. The friction forces versus the velocity were measured, and the viscous friction, Coulomb friction, and stiction were identified. With a nominal PID (proportional-integral-derivative) controller, we observed the adverse effects due to friction, such as excessive steady-state errors, oscillations, and limit-cycles. By adding an adequate friction model as part of the augmented nonlinear dynamics of a plant, we were able to conduct a simulation study of a motion control system that well matched experimental results. We have observed that the implementation of a model-based friction compensator improves the overall performance of both motion control systems, i.e., the rotary motion control system and the Altino testbed for autonomous vehicle development. By utilizing a better simulation tool with an embedded friction model, we expect that the overall development time and cost can be reduced.

Constant Altitude Flight Control for Quadrotor UAVs with Dynamic Feedforward Compensation

  • Razinkova, Anastasia;Kang, Byung-Jun;Cho, Hyun-Chan;Jeon, Hong-Tae
    • International Journal of Fuzzy Logic and Intelligent Systems
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    • v.14 no.1
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    • pp.26-33
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    • 2014
  • This study addresses the control problem of an unmanned aerial vehicle (UAV) during the transition period when the flying mode changes from hovering to translational motion in the horizontal plane. First, we introduce a compensation algorithm that improves height stabilization and reduces altitude drop. The main principle is to incorporate pitch and roll measurements into the feedforward term of the altitude controller to provide a larger thrust force. To further improve altitude control, we propose the fuzzy logic controller that improves system behavior. Simulation results presented in the paper highlight the effectiveness of the proposed controllers.

Dynamic Workspace Control of Underwater Manipulator Considering ROV Motion (ROV의 운동이 고려된 수중 로봇팔의 동적 작업공간 구동 제어)

  • Shim, Hyung-Won;Jun, Bong-Huan;Lee, Pan-Mook
    • Journal of Institute of Control, Robotics and Systems
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    • v.17 no.5
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    • pp.460-470
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    • 2011
  • This paper presents a dynamic workspace control method of underwater manipulator considering a floating ROV (Remotely Operated vehicle) motion caused by sea wave. This method is necessary for the underwater work required linear motion control of a manipulator's end-effector mounted on a floating ROV in undersea. In the proposed method, the motion of ROV is modeled as nonlinear first-order differential equation excluded dynamic elements. For online manipulator control achievement, we develop the position tracking method based on sensor data and EKF (Extended Kalman Filter) and the input velocity compensation method. The dynamic workspace control method is established by applying these methods to differential inverse kinematics solution. For verification of the proposed method, experimental data based test of ROV position tracking and simulation of the proposed control method are performed, which is based on the specification of the KORDI deep-sea ROV Hemire.

Precision Stabilization Control of Servo-system by Using Friction Compensation (마찰보상을 통한 서어보제어계의 정밀 안정화 제어)

  • Kang, Min-Sig
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.3 s.96
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    • pp.109-115
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    • 1999
  • This paper presents a stabilization control designed to improve position stabilization performance of a position servo-system(turret) mounted on a manuvering platform(vehicle). In the consideration of the motion of the platform, a dynamic model of the stabilization system is derived and shows the viscous and stick-slip friction torques are the major source of stabilization errors. An extended generalized minimum variance control which consists of a feedforward disturbance compensation as well as a pole placement feedback control is suggested to reduce the stabilization errors caused from the friction disturbances. This modeling and control are applied to a small experimental set-up and the experimental results confirm the accuracy of the model and the effectiveness of the suggested control.

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Disturbance Compensation Control in Active Magnetic Bearing Systems by Filtered-x LMS Algorithm (전자기베어링에서 Filtered-x LMS 알고리즘을 이용한 외란보상 제어기 설계)

  • 강민식;강윤식;이대옥
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.447-450
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    • 2003
  • This paper concerns on application of active magnetic bearing(AMB) system to levitate the elevation axis of an electro-optical sight mounted on moving vehicles. In such a system. it is desirable to retain the elevation axis within the predetermined air-gap while the vehicle is moving. A disturbance compensation control is proposed to reduce the base motion response. In the consideration of the uncertainty of the system model, a filtered-x least-mean-square(FXLMS) algorithm is used to estimate adaptively the frequency response function of the feedforward control which cancels disturbance responses. The frequency response function is fitted to an optimal feedforward control. Experimental results demonstrate that the proposed control reduces the air-gap deviation to 27.7% that by feedback control alone.

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A Study on the Improvement of the Image Quality for UAV Using Drift Compensation (편류보정을 통한 무인항공기 영상품질 향상에 관한 연구)

  • Lee, Mal-Young
    • Journal of Korean Society for Quality Management
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    • v.41 no.3
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    • pp.405-412
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    • 2013
  • Purpose: In this paper, the improvement of the image quality is investigated. The image quality is degraded by the drift phenomenon of EO/IR (Electro-Optical/Infrared) device on UAV. The drift phenomenon means that the image of EO/IR equipment on UAV(Unmanned Aerial Vehicle) moves to the unintended direction. This phenomenon should be improved for successful flight mission. Methods: To improve the drift phenomenon, the drift compensation method, the combination algorithm of FMC(Forward Motion Compensation) and AMC(Angular Motion Compensation) method, are introduced to calculate pitch and azimuth angle. Result values of pitch and azimuth angle are used for the improvement of image quality in EO/IR control logic. Results: The image quality is quantitatively improved more than 15 times through field test data of flight. Conclusion: Using the drift compensation technique, the image quality for EO/IR equipment is improved over 15 times than existing methods. This means the user of UAV with EO/IR device can perform a successful mission by keeping the line of sight for the target accurately.

Control of Inertially Stabilized Platform Using Disturbance Torque Estimation and Compensation (외란토크 추정 및 보상을 이용한 관성안정화 플랫폼의 제어)

  • Choi, Kyungjun;Won, Mooncheol
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.40 no.1
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    • pp.1-8
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    • 2016
  • In this study, we propose a control algorithm for Inertially Stabilized Platforms (ISP), which combines Disturbance Observer (DOB) with conventional proportional integral derivative (PID) control algorithm. A single axis ISP system was constructed using a direct drive motor. The joint friction was modeled as a nonlinear function of joint speed while the accuracy of the model was verified through experiments and simulation. In addition, various Q-filters, which have different orders and relative degrees of freedom (DOF), were implemented. The stability and performance of the ISP were compared through experimental study. The performance of the proposed PID-plus-DOB algorithm was compared with the experimental results of the conventional double loop PID control under artificial vehicle motion provided motion simulator with six DOF.

Quadrotor Attitude Stabilization by Using PID Controller (PID 제어기를 이용한 쿼드로터 자세 안정화)

  • Kim, Yongyoung;Shin, Junhee;Lee, Sunik;Lee, Hyounggon;Lim, Hyunmin;Kim, Kwangjin;Lee, Sangchul
    • Journal of Aerospace System Engineering
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    • v.4 no.4
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    • pp.18-27
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    • 2010
  • Quadrotor is an aircraft which is possible in Vertical Take-off and Landing(VTOL). This aircraft can not only be created as an Unmanned Aerial Vehicle(UAV), but also can be easily used in various fields because of its simplicity of construction. This study is mainly conducted with two main purposes. The first goal is designing the quadrotor focusing on the lightweight and protecting the airframe. The second purpose is stabilizing the quadrotor's attitude by using the PID controller. MATLAB simulation is performed for obtaining PID gain based on equations of motion. We used the compensation filter technique for the calibration of sensor data. PID gain has been drawn out based on the MATLAB simulation. The efficiency of the attitude control is improved by calibration of sensor data.

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