• Title/Summary/Keyword: roll to roll system

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Ship Motion-Based Prediction of Damage Locations Using Bidirectional Long Short-Term Memory

  • Son, Hye-young;Kim, Gi-yong;Kang, Hee-jin;Choi, Jin;Lee, Dong-kon;Shin, Sung-chul
    • Journal of Ocean Engineering and Technology
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    • v.36 no.5
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    • pp.295-302
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    • 2022
  • The initial response to a marine accident can play a key role to minimize the accident. Therefore, various decision support systems have been developed using sensors, simulations, and active response equipment. In this study, we developed an algorithm to predict damage locations using ship motion data with bidirectional long short-term memory (BiLSTM), a type of recurrent neural network. To reflect the low frequency ship motion characteristics, 200 time-series data collected for 100 s were considered as input values. Heave, roll, and pitch were used as features for the prediction model. The F1-score of the BiLSTM model was 0.92; this was an improvement over the F1-score of 0.90 of a prior model. Furthermore, 53 of 75 locations of damage had an F1-score above 0.90. The model predicted the damage location with high accuracy, allowing for a quick initial response even if the ship did not have flood sensors. The model can be used as input data with high accuracy for a real-time progressive flooding simulator on board.

An Image-based Ship Attitude Estimation Method for Helicopter Landing (회전익 항공기의 착함을 위한 이미지 기반 함정 자세 예측)

  • Geonha Park;Sunghoon Jung
    • Journal of the Korea Institute of Military Science and Technology
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    • v.27 no.6
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    • pp.677-683
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    • 2024
  • Landing a helicopter on a moving ship requires accounting for the ship's attitude. However, it is not only challenging to visually assess the ship's attitude, but it also creates illusions for the pilot, increasing the risk of accidents. In this study, we propose an image-based ship attitude estimation method to assist helicopter landings. The proposed method enhances landing safety by predicting the ship's heave, pitch, and roll using only helicopter-mounted optical devices and pre-trained deep learning models, without requiring communication with the ship. To implement this approach, we generated a dataset by simulating a virtual sea environment and ship motion. Using this data, we trained deep learning models to predict the ship's attitude based solely on images. Experimental results confirm the feasibility of the proposed method, with VGG-16 demonstrating particularly effective attitude prediction under simulated conditions.

An Experimental Study on Mass Driving Anti-Rolling System for Ships (가동질량을 이용한 선박용 횡동요 저감장치에 대한 실험적 연구)

  • Moon, Seok-Jun;Jeong, Jong-Ahn;Yoon, Hyeon-Kyu;Lee, Gyeong-Joong;Ann, Seong-Phil
    • Journal of the Society of Naval Architects of Korea
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    • v.42 no.6 s.144
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    • pp.666-672
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    • 2005
  • Reduction of a ship's rolling is the most important performance requirement for improving the safety of the crew on board and preventing damage to cargos as well as improving the comfort of the ride. A mass driving anti-rolling system (MO-ARS) might be one candidate of several systems against the ship's rolling. In this paper, three types of MD-ARS, two passive and one active devices, are developed for small ships. After they are installed on the cabin of the small leisure boat, respectively, a series of performance test is conducted before and after operating them. Through the test, it is confirmed that the roll responses of the ship are pretty well reduced by the MO-ARS.

The Evaluation of Accuracy for Airborne Laser Surveying via LiDAR System Calibration (시스템 초기화(Calibration)에 따른 항공레이저측량의 정확도 평가)

  • 이대희;위광재;김승용;김갑진;이재원
    • Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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    • 2004.04a
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    • pp.15-26
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    • 2004
  • The calibration for systematic error in LiDAR is crucial for the accuracy of airborne laser scanning. The main error is the misalignment of platforms between INS(Inertial Navigation System) and Laser scanner For planimetrical calibration of LiDAR, the building is good feature which has great changes in height and continuous flat area in the top. The planimetry error(pitch, roll) is corrected by adjustment of height which is calculated from comparing ground control points(GCP) of building to laser scanning data. We can know scale correction of laser range by the comparison of LiDAR data and GCP is arranged at the end of scan angle where maximize the height error. The area for scale calibration have to be large flat and have almost same elevation. At 1000m for average flying height, The Accuracy of laser scanning data using LiDAR is within 110cm in height and ${\pm}$50cm in planmetry so we can use laser scanning data for generating 3D terrain surface, expecically digital surface model(DSM) which is difficult to measure by aerial photogrammetry in forest, coast, urban area of high buildings

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Design of Robotic Prosthetic Leg for Above-knee Amputees (대퇴 절단자들을 위한 로봇 의지의 설계)

  • Yang, Un-Je;Kim, Jung-Yup
    • Journal of the Korean Society for Precision Engineering
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    • v.31 no.10
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    • pp.913-922
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    • 2014
  • This paper describes design of a robotic above-knee prosthetic leg which is powered by electrical motors. As a special feature, the robotic prosthetic leg has enough D.O.F.s. For mimicking the human leg, the robotic prosthetic leg is composed of five joints. Three of them are called 'active joint' which is driven by electrical motors. They are placed at the knee-pitch-axis, the ankle-pitch-axis, and the an! kle-roll-axis. Every 'active joint' has enough torque capacity to overcome ground reaction forces for walking and is backlashless for accurate motion generation and high-performance balance control. Other two joints are called 'passive joint' which is activating by torsion spring. They are placed at the toe part and designed by Crank-rocker mechanism using kinematic design approach. In order to verify working performance of the robotic prosthetic leg, we designed a gait trajectory through motion capture technique and experimentally applied it to the robot.

Minimization of Welding Defect in $CO_2$ Laser Welded Tube

  • Suh Jeong;Kang Hee-Shin;Lee Jae-Hoon;Park Kyoung-Taik;Lee Moon-Yong;Jung Byung-Hun
    • International Journal of Precision Engineering and Manufacturing
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    • v.6 no.3
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    • pp.19-23
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    • 2005
  • To minimize the weld defect in manufacturing of the welded tube by using $CO_2$ laser, the monitoring of the welding quality and the seam tracking along the butt-joint lengthwise to the tube axis are studied. The longitudinal butt-joint is shaped from $60kgf/mm^2$ grade steel sheet by 2 roll bending method, and welded by the $CO_2$ laser welding system equipped with the seam tracker and plasma sensor. The laser welded tube has the thickness of 1.5mm, diameter of 105.4mm and length of 2000mm. The precise positioning of the laser beam on the butt-joint to be assembled is obtained within $200{\mu}m$ by the laser vision sensor. The artificial defects in the butt-joint are well observed by the signal of plasma intensity measured from the plasma sensor of UV wavelength range within 400nm. The developed $CO_2$ laser tube welding system has the function of the precision seam tracking and the real-time monitoring of the welding quality. In conclusion, the laser welded tube can be used for manufacturing of automobile chassis and components after hydro-forming.

Development of 3-Dimensional Pose Estimation Algorithm using Inertial Sensors for Humanoid Robot (관성 센서를 이용한 휴머노이드 로봇용 3축 자세 추정 알고리듬 개발)

  • Lee, Ah-Lam;Kim, Jung-Han
    • Journal of Institute of Control, Robotics and Systems
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    • v.14 no.2
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    • pp.133-140
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    • 2008
  • In this paper, a small and effective attitude estimation system for a humanoid robot was developed. Four small inertial sensors were packed and used for inertial measurements(3D accelerometer and three 1D gyroscopes.) An effective 3D pose estimation algorithm for low cost DSP using an extended Kalman filter was developed and evaluated. The 3D pose estimation algorithm has a very simple structure composed by 3 modules of a linear acceleration estimator, an external acceleration detector and an pseudo-accelerometer output estimator. The algorithm also has an effective switching structure based on probability and simple feedback loop for the extended Kalman filter. A special test equipment using linear motor for the testing of the 3D pose sensor was developed and the experimental results showed its very fast convergence to real values and effective responses. Popular DSP of TMS320F2812 was used to calculate robot's 3D attitude and translated acceleration, and the whole system were packed in a small size for humanoids robots. The output of the 3D sensors(pitch, roll, 3D linear acceleration, and 3D angular rate) can be transmitted to a humanoid robot at 200Hz frequency.

A Study of Aircraft Ground Motion (항공기 지상운동 특성에 관한 연구)

  • Song, Won Jong
    • Journal of Aerospace System Engineering
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    • v.11 no.6
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    • pp.17-25
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    • 2017
  • Vertical reaction force between ground and tire is an important parameter determining the ground behavior characteristics of aircraft. This parameter can be used to calculate the lateral force and friction. However, it is hard to obtain this parameter in real-time when the aircraft is taxiing. Therefore, pre-analysis of ground behavior and vertical reaction force should be conducted using ground simulation results to prevent rollover or hazardous scenarios. In this paper, a Landing Gear and Full-Aircraft model was constructed using VI-Aircraft S/W. The roll behavior of aircraft was analyzed using steering simulation results compared with taxi-test data.

Stabilization Technique for a Dual-axis Rotational Inertial Navigation System considering Waves (파도를 고려한 2축 회전형 관성항법시스템의 안정화 기법)

  • Myeong-Seok Chae;Seong-Yun Cho;Chan-Gook Park;Min-Su Jo;Chan-Joo Park
    • The Journal of the Korea institute of electronic communication sciences
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    • v.19 no.2
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    • pp.437-444
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    • 2024
  • The rotational inertial navigation system can provide more accurate navigation information by mounting an IMU (Inertial Measurement Unit) on the gimbal and rotating the gimbal regularly to cancel out the errors of the IMU. However, when an attitude change occurs due to waves, the attitude error is not removed to 0 at the end of one cycle of the rotation procedure and causes a large position error. In this paper, considering this problem, we propose a method of stabilizing the external gimbal by rotating it based on the roll information of the vehicle. Based on simulation, the impact of waves is analyzed and the performance of external gimbal stabilization is verified.

Adsorption Characteristics of Acetone, Benzene, and Metylmercaptan in the Fixed Bed Reactor Packed with Activated Carbon Prepared from Waste Citrus Peel (폐감귤박으로 제조한 활성탄을 충전한 고정층 반응기에서 아세톤, 벤젠 및 메틸메르캅탄의 흡착특성)

  • Kam, Sang-Kyu;Kang, Kyung-Ho;Lee, Min-Gyu
    • Applied Chemistry for Engineering
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    • v.29 no.1
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    • pp.28-36
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    • 2018
  • Adsorption experiments of three target gases such as acetone, benzene, and methyl mercaptan (MM) were carried in a continuous reactor using the activated carbon prepared from waste citrus peel. In a single gas system, the breakthrough time obtained from using the activated carbon (WCAC) prepared from waste citrus peel. In a single gas system, the breakthrough time obtained from the breakthrough curve decreased with increasing the inlet concentration and flow rate, but increased with respect to the aspect ratio (L/D). Adsorbed amounts of the target gases by WCAC increased as a function of the inlet concentration and aspect ratio. However, adsorbed amounts with the increase of the flow rate were different depending upon target gases. Results from the breakthrough time and adsorbed amount showed that the affinity for WCAC was the highest in benzene, followed by acetone and then MM. On the other hand, in the binary and ternary systems, the breakthrough curve showed a roll-up phenomenon where the adsorbate having a small affinity for WCAC was replaced with the adsorbate with a high affinity. The adsorption of acetone on WCAC was more strongly affected when mixing with the nonpolar benzene than that of using sulfur compound MM.