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Now showing items 1 - 10 of 10

  • Model-based Position Tracking Control of a Hose-connected Hydraulic Lifting System

    Hou, Jiaoyi   Zhang, Zengmeng   Ning, Dayong   Gong, Yongjun  

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  • Nonlinear Dynamics Modeling and Analysis of Underwater Mud-Penetrator Steering System

    Chen, Yinglong   Liu, Hui   Zhang, Zengmeng   Hou, Jiaoyi   Gong, Yongjun  

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  • Hydraulic systems control based on the characteristics of major-motion mechanism for an open-die forging manipulator

    Hou, Jiaoyi   Zhang, Zengmeng   Zhou, Hua   Ning, Dayong   Gong, Yongjun  

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  • Theoretical and experimental study of scour depth by submerged water jet

    Hou, Jiaoyi   Zhang, Lishan   Gong, Yongjun   Ning, Dayong   Zhang, Zengmeng  

    The characteristics and working principles of the impinging by submerged water jet are analyzed, and the relevant mathematical model is optimized based on Rajaratnam's theoretical and experimental study. A new mathematical model is constructed by adding an important parameter called impinging angle. A new experiment is designed according to the working conditions of various impinging distances and angles. In combination with the experiment data and with the use of the curve fitting method, the functional relationship between the impinging distance and angle as well as the coefficient C-4 is obtained. The experiment results show that the scour depth decreases as impinging distance increases, followed by a trend from decline to rise before falling again; those two turning points occur within the range of 20d-25d. The scour depth constantly increases with rising impinging angle, and the maximum and minimum increasing ranges can reach 180% and 50%, respectively, with the impinging angle increasing from 40 degrees to 90 degrees
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  • Fault diagnosis of synchronous hydraulic motor based on acoustic signals

    Hou, Jiaoyi   Sun, Hongyu   Xu, Aoyu   Gong, Yongjun   Ning, Dayong  

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  • Auto-identification of engine fault acoustic signal through inverse trigonometric instantaneous frequency analysis

    Ning, Dayong   Hou, Jiaoyi   Gong, Yongjun   Zhang, Zengmeng   Sun, Changle  

    The acoustic signals of internal combustion engines contain valuable information about the condition of engines. These signals can be used to detect incipient faults in engines. However, these signals are complex and composed of a faulty component and other noise signals of background. As such, engine conditions' characteristics are difficult to extract through wavelet transformation and acoustic emission techniques. In this study, an instantaneous frequency analysis method was proposed. A new time-frequency model was constructed using a fixed amplitude and a variable cycle sine function to fit adjacent points gradually from a time domain signal. The instantaneous frequency corresponds to single value at any time. This study also introduced instantaneous frequency calculation on the basis of an inverse trigonometric fitting method at any time. The mean value of all local maximum values was then considered to identify the engine condition automatically. Results revealed that the mean of local maximum values under faulty conditions differs from the normal mean. An experiment case was also conducted to illustrate the availability of the proposed method. Using the proposed time-frequency model, we can identify engine condition and determine abnormal sound produced by faulty engines.
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  • Hydraulic systems control based on the characteristics of major-motion mechanism for an open-die forging manipulator

    Hou, Jiaoyi   Zhang, Zengmeng   Zhou, Hua   Ning, Dayong   Gong, Yongjun  

    In the open-die forging process, the forging manipulator must cooperate closely with the forging press. Terrible working conditions of open-die forging have resulted in significant demand on the hydraulic control systems of the forging manipulator. This article analyzes the characteristics of major-motion hydraulic systems with the aim of proposing a novel hybrid serial-parallel heavy-duty forging manipulator. Kinematic and dynamic models of the major-motion mechanism are developed to investigate the control and comply with performance of hydraulic lifting, pitching, and buffering systems. Simulation shows that the three hydraulic systems are coupled in the position and posture control of the clamp. A separate posture control method based on the characteristic of the major-motion mechanism is designed for the hydraulic systems, and the position tracking performance of the hydraulic systems is studied in a stretching process of a plat-tool.
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  • Position/force control of master–slave antagonistic joint actuated by water hydraulic artificial muscles

    Ning, Dayong   Che, Jinkai   Zhang, Zengmeng   Tian, Hao   Hou, Jiaoyi   Gong, Yongjun  

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  • Model-based position tracking control of a hose-connected hydraulic lifting system

    Hou, Jiaoyi   Zhang, Zengmeng   Ning, Dayong   Gong, Yongjun  

    High-pressure rubber hose is normally used to connect the control valves and actuators of hydraulic systems and thus lower their natural frequency. PID control is preferred in industrial hydraulic systems as it has many advantages over other controls. However, the low natural frequency of hose-connected systems limits the performance of PID control. In this paper, a hose-connected hydraulic lifting test rig is presented and the mathematical model of the system is proposed. Valve compensation strategy and hose compensation strategy are designed based respectively on the flow characteristic of the proportional valve and the mathematical model of the hose. Comparative experiments with typical desired trajectories are carried out in the test rig. Results show that both the compensation strategies are effective in improving the tracking accuracy. (C) 2016 Published by Elsevier Ltd.
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  • Underwater acoustic beacon signal extraction based on dislocation superimposed method

    Zhang, Zengmeng   Cheng, Xing   Ning, Dayong   Hou, Jiaoyi   Gong, Yongjun  

    Flight data are recorded in an acoustic beacon. A new signal extraction method led by random decrement technique is proposed to detect sound signals from thousands of meters under the sea. This method involves dislocation superimposed method and cross-correlation function to extract acoustic beacon signals with noise interference. First, the starting point is selected and the length of each segment is determined via two superposition ways. Second, the signal segment for linear superposition is intercepted to complete acoustic beacon signal extraction. Finally, the signals are subjected to cross-correlation and energy analyses to determine the accuracy of interception signals. During the experiment, the collected acoustic beacon signal is used as the test signal, and the signal is obtained as the simulation signal on the basis of the parameters of acoustic beacons. Results show that the correlation between the synthetic and concerned signals is more than 80% after a number of superposition are performed and the extraction effect is remarkable. Dislocation superimposed method is simple and easily operated, and the extracted signal waveform yields a high accuracy.
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