Pinsopon, Unnat

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Pinsopon, Unnat
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Email
unnat.pi@kmitl.ac.th

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    Velocity control of electro-hydraulic pump control system using gear pump
    (2018-12-01)
    Jangnoi, Tossapol
    ;
    Pinsopon, Unnat
    Two types of velocity control electro-hydraulic systems, valve and pump flow control systems, were extensively investigated in this study. Valve flow control system tested in the study was one of the conventional types with the use of proportional valve and conventional gear pump. The proposed pump flow control system was of the simplest one. An inverter type variable speed drive was used to drive the same gear pump in order to adjust the pump speed and hence the discharge flow rate according to the desired cylinder velocity. Mathematical model of the pump flow control system is presented in the article, and its numerical simulation results were obtained by solving the state space equations. Open loop and proportional-integral (PI) closed loop performances of both valve and proposed pump flow control systems were tested and compared. Velocity tracking performance of valve flow control system either under open loop or PI closed loop control was always better than the proposed pump flow control system. However, the power consumption of the proposed system was much better than the valve flow control system. Response speed in terms of bandwidth frequency of the proposed system under open loop control was less than the valve flow control system by half due to the large inertia of motor-pump rotor. Under PI closed loop control, bandwidth frequency of the proposed system was improved to be 15% less than the valve flow control system.
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    Experimental study on sound characteristics of Ja-Khay strings
    (2019-07-01)
    Wangwiwattana, Teerawat
    ;
    Saguanrum, Sayam
    ;
    Kittimathaveenan, Kajornsak
    ;
    Pinsopon, Unnat
    This research explored sound characteristics of eight different strings on Ja-Khay, a Thai classical floor zither. The strings were investigated the suitability of being the first brightest string. Physical properties of each string such as linear density, elastic modulus and tension required to make a 262 Hz C<inf>4</inf>-note sound were tested and measured. The sound produced by each string was recorded in the recording studio of Music Engineering and Multimedia Department, King Mongkut's Institute of Technology Ladkrabang. Temporal and spectral responses of the sound produced by eight test strings were analyzed. The relationship between physical properties and sound characteristics such as maximum loudness, sustain, richness and brightness of the sound was investigated. The good sound characteristics of three most well-liked strings according to the survey: Construction string number 120, tennis string and Saw-U silk string, were confirmed by the analytical data.
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    A model-reference sliding mode for dual-stage actuator servo control in HDD
    (2014-01-01)
    Sonkham, Siwaphon
    ;
    Pinsopon, Unnat
    ;
    Chatlatanagulchai, Withit
    This paper presents a method of sliding mode control (SMC) designing and developing for the servo system in a dual-stage actuator (DSA) hard disk drive. Mathematical model of hard disk drive actuators is obtained, extracted from measuring frequency response of the voice-coil motor (VCM) and micro-actuator separately. The Matlab software tools are used for mathematical model estimation and also for controller design and simulation. A model-reference approach for tracking requirement is selected as a proposed technique. The simulation results show that performance of the model-reference SMC controller in DSA servo control can be satisfied in the tracking error, as well as keeping the positioning of the head within the boundary of +/-5% of track width under the presence of disturbance. The overall results of model-reference SMC design in DSA are met per requirement specifications and significant reduction in %off track is found when compared to the singlestate actuator (SSA). © 2014 IEEE.
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    PID electro-hydraulic cylinder force tracking system with friction compensation
    (2018-08-14)
    Chanbua, Weerapong
    ;
    Pinsopon, Unnat
    Friction can be found in all mechanical systems, and is the cause of control tracking error. In this article, LuGre friction model for symmetric hydraulic cylinder was studied and obtained experimentally. The estimated friction force was applied for reference force compensation. Force tracking performances of PID force control systems with and without friction compensation were tested and compared. Control system with friction compensation outperformed one without in all cases of tracking tests. The best result was found in the square force tracking tests, with an average error at maximum compression force of 86.105 N in the case of with friction compensation compared with error of 511.996 N in the case without. However, the estimated friction achieved in the study was noisy. This is due to the use of noisy numerically differentiated velocity signal in the friction estimation procedure.
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    Influence of RBD palm olein on hydraulic pump performance
    (2014-01-01)
    Chanbua, Weerapong
    ;
    Pinsopon, Unnat
    At the present time, researchers try to find alternative fluids for being used as lubricants or hydraulic fluids that are biodegradable and environmental friendly. In this study, Refined- Bleached-Deodorized (RBD) palm olein was investigated whether it is such a potential candidate. RBD palm olein could be easily acquired since it is of the type used as cooking oil. The physical properties of both conventional hydraulic oil and RBD palm olein were tested and compared by an accredited laboratory. The performance of the hydraulic systems when using both fluids as working mediums were also tested and compared. The experimental results show that temperature significantly affected the performance of the hydraulic system when using conventional hydraulic oil, whereas the performance of the hydraulic system when using RBD palm olein barely changed with temperatures. At the temperatures below 60°C, the RBD palm olein yielded less flow rate and less energy efficiency. However, for the temperatures above 60°C, the RBD palm olein yielded slightly more flow rate and slightly more energy efficiency. It can be confirmed from this study that RBD palm olein can be used as an alternative hydraulic fluid. © (2014) Trans Tech Publications, Switzerland.