Benjanarasuth, Taworn

Preferred name

Alternative Name

Benjanarasuth, T.

Main Affiliation

School of Engineering

taworn.be@kmitl.ac.th

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Robust hybrid control for two-dimensional handheld micromanipulator
(2014-01-01)
Boksuwan, Sungwan
;
Benjanarasuth, Taworn
;
Kanamori, Chisato
;
Aoyama, Hisayuki
This paper proposes a two-dimensional handheld mi-cromanipulator oriented toward bio cell handling. The micromanipulator consists of two flexible links, each of which is constructed with a parallel beam structure. Electric coils and permanent magnets are used to produce an actuator to form double drivers. An explicit model predictive control combined with a PID controller called a robust hybrid control is proposed not only to achieve robust tracking performance, but also to dampen the vibration of the mechanism. The experimental results are compared to results from a standard PID controller to investigate the effectiveness of the micromanipulator.
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Mg Alloy Rod Strengthened by Combined Processes of Deformation-Restricted Forging and Extrusion
(2024-01-01)
Miura, H.
;
Oba, Y.
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Watanabe, C.
;
Benjanarasuth, T.
A new method for strengthening Mg alloy rod is proposed. AZ80Mg alloy rods were forged along the longitudinal axis (LA) at extremely high pressures beyond fracture stress under a condition where plastic deformation was eliminated in a die, i.e., deformation-restricted forging (DRFing), followed by cold extrusion. Although the ultimate tensile strength (UTS) and hardness were gradually raised with DRFing stress, the yield strength (YS) was lowered by sharp basal texture evolution on the plane normal to the LA and tensile axis. However, the extrusion after DRFing drastically changed the texture to (0001) LA, causing a large increase in YS. Consequently, a superior balance of mechanical properties: YS of 376 MPa, UTS of 417 MPa, and ductility of 10%, could be achieved after the combined processes of DRFing and extrusion.
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An approach for room-temperature multi-directional forging of pure titanium for strengthening
(2018-07-25)
Miura, H.
;
Kobayashi, M.
;
Aoba, T.
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Aoyama, H.
;
Benjanarasuth, T.
Commercially pure Ti grade 2 was multi-directionally forged (MDFed) at room temperature. MDFing could be successfully carried out without any cracking to a cumulative strain of ΣΔε = 2.0. Ultrafine-grained (UFGed) structure gradually developed with increasing cumulative strain mainly by mechanical twinning and kinking. An average grain size of approximately 400 nm was attained. The mechanical properties were drastically modified by the grain refinement and a superior balance of tensile strength and ductility, 710 MPa and 21%, was achieved. Additional cold rolling of the UFGed Ti possessed further better mechanical properties of 930 MPa tensile strength and 19% ductility.
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Robust real-time model predictive control for torsional vibration system
(2012-01-01)
Boksuwan, Sungwan
;
Benjanarasuth, Taworn
In this paper, explicit, robust Model Predictive Control (MPC) is proposed for the control of a two-mass system in order to achieve not only good tracking performance and load-change effect rejection, but also low torsional vibration, when the measurement noise contains outliers. The control structure presented in this paper is based fundamentally on the combination of explicit MPC and region detection via a self-optimizing variable. In addition, the well-known Kalman filter is replaced by the robust Kalman filter to deal with the outlier signals. The effectiveness of the proposed method is compared with a PID-based control.
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High-Temperature Deformation and Subsequent Static Recrystallization Behavior of Ultra-Low Stacking-Fault Energy Cu-Zn-Si Alloys
(2026-01-01)
Miura, Hiromi
;
Kasuya, Sanshiro
;
Oba, Yojiro
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Okada, Takuya
;
Watanabe, Chihiro
Behaviors of high-temperature deformation followed by annealing and static recrystallization (SRX) in Cu-Zn-Si alloys with ultra-low stacking-fault energy (SFE) were investigated. The peak stress, steady-state flow stress and grain size during high-temperature deformation appeared to decrease with decreasing SFE, which would suggest easier occurrence of dynamic recrystallization (DRX) with decreasing SFE. Nevertheless, with increasing initial grain size, onset of DRX was much delayed even at higher temperatures and lower strain rates. SRX started after annealing for rather long periods of time contrary to the expectation that SRX should be stimulated because of meta-DRX. New grains evolved by DRX and SRX contained quite high density of annealing twins, showing DRX and SRX mechanisms induced by annealing twin formation during grain-boundary migration. [doi:10.2320/matertrans.MT-D2025015]
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CDM-based two degree of freedom PI controller tuning rules for stable and unstable FOPTD processes and pure integrating processes with time delay
(2019-01-01)
Somasundaram, S.
;
Benjanarasuth, T.
This work proposes the coefficient diagram method (CDM)-based two degree of freedom proportional integral (CDM-PI) controller tuning rules for stable and unstable first order plus time delay (FOPTD) processes and pure integrating processes with time delay (PIPTD). To derive the tuning rules, a general first order plus time delay (FOPTD) model, the first order Taylor denominator (TD) approximation technique and the pole allocation strategy named CDM is used. The tuning rules derived here are novel and they relate the controller parameters to the process model parameters directly. The performance of the CDM-PI controller utilising the proposed tuning rules is tested with numerical examples of stable, unstable and pure integrating processes with time delay models. The test results indicate that the proposed tuning rules yield promising results over the other PI controllers. Performance measures confirm the effectiveness of the proposed tuning method.
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New tuning formulas for two-degree of freedom PID controllers and the application to level control systems
(2007-01-01)
Benjanarasuth, Taworn
;
Ngamwiwit, Jongkol
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Komine, Noriyuki
;
Ochiai, Yasuzumi
This paper presents novel tuning formulas for two-degree of freedom PID-family controllers. The structure of the proposed control system consists of a plant or process to be controlled, P or PI or PID controllers and a pre-filter. The tuning formulas are derived based on the CDM design method by solving CDM algebraic equations obtained from the known controllers' structures and the approximated plant model based on the experimental test. The proposed formulas are summarized in the tuning table and can be used easily. To apply the tuning rules, the plant or process is firstly tested to find the values of critical gain and critical period experimentally in the same manner as Ziegler-Nichols' second method. The parameters of P, PI or PID controller and the associated pre-filter are then obtained by substituting those values in the formulas. The experiments in controlling the level process with long pipeline controlled by the controllers tuned by the proposed rules and the well-known Ziegler-Nichols' formulas are conducted and compared. The proposed control systems result in responses with shorter settling time and considerably smaller or no overshoot. Overall, the proposed formulas are well applicable despite their simplicity.
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Simplified controller design for output performance under common input limitations with generalized integral anti-windup for a class of processes
(2020-06-01)
Benjanarasuth, Taworn
One of basic key tasks of a control system design is to achieve the desired output responses both in transient and steady states. Besides, the common input limitations, such as saturation and slew rate or at least avoiding a sudden jump in the command signal, must be considered in practice. However, popular controllers such as PI and PID cause sudden changes or even impulsive surges in the command signal under external excitations by a step reference input and/or step input/output disturbances. In this paper, a simplified controller design with its preferred structure models to meet the mentioned requirements is presented for a class of minimum-phase stable linear time-invariant single-input single-output processes with proper real rational transfer function. The structure of such controller is mathematically investigated and the result is that the controller must be strictly proper and containing an integral factor. The design procedure is simple and straightforward based on reference model matching and model cancellation with only two required conditions on the desired closed-loop transfer function which are its relative degree comparing to the processes to be controlled and the equality of the lower order coefficient(s) in its numerator and denominator polynomials. A generalized integral anti-windup structure, based on back calculation method and PI/PID anti-windup scheme, to lessen the saturation effect on the integral action of the proposed controller is additionally introduced by rearranging the controller in a parallel form with one separated integral control action portion. Numerical examples are investigated to demonstrate the design procedure and verify the success of the proposed controller to the required objectives.
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Internet based crossover robot remote control competition among Asian countries
(2013-01-01)
Xu, C.
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Ming, A.
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Kanamori, C.
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Aoyama, H.
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Li, H.
We introduce an internet based crossover robot remote control competition project that is an international cooperative program based in Japan, China, Thailand, and Taiwan. This competition is an important component of a long-term higher education reform project aiming to develop a practice based innovative educational methodology jointly promoted by the Ministry of Education, Culture, Sports, Science & Technology of Japan and the University of Electro-Communications. The competition project includes two subjects: the competition itself and the communication and cooperation between students in two countries. The basic mode of the competition is a locally controlled robot and a remotely controlled robot cooperate with each other to complete some tasks. As a unique feature of the project, the student-student communication and cooperation are increased through a specially designed team organization structure that each team consists of two groups from different universities in different countries and the team members are required to cooperate through the internet to complete the competition. The competition has been successfully held four times and the results show it greatly benefits the students, and is expected to promote the development of the practice based educational methodology in the near future. © 2013 Elsevier Ltd. All rights reserved.
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Effects of strain rate during multi-directional forging on grain refinement and mechanical properties of AZ80Mg alloy
(2016-01-01)
Miura, H.
;
Kobayashi, M.
;
Benjanarasuth, T.
Samples of AZ80Mg alloy were multi-directionally forged (MDFed) at various strain rates in the rage from 3.0× 10-3 s-1 to 3.0× 10-1 s-1 under decreasing temperature conditions. The MDFing pass temperatures employed were 653 K, 605 K and 553 K. These passes, each of 0.5 strain, were applied up to a cumulative strain of ΣΔϵ= 1.5 at maximum. The average grain size decreased with increasing cumulative strain and depended only weakly on the strain rate. Microstructures with average grain sizes of 0.84 μm, 0.88 μm and 1.2 μm were attained when MDFed at strain rates of 3.0× 10-1 s-1, 3.0× 10-2 s-1 and 3.0×10-3 s-1. The microstructure evolved at 3.0× 10-1 s-1 was less homogeneous. This difference is interpreted as being due to the higher stored energy causing static recrystallization in the latter MDFing condition. As a result, the best balance of the mechanical properties was attained by MDFing at 3.0× 10-2 s-1. In this case, ultimate tensile strength (UTS) of 445 MPa was achieved together with a fracture strain of 22%. By comparison, MDFing at 3.0× 10-1 s-1 led to lower UTS and ductility of 410 MPa and 15% while the yield stresses were comparable.

Benjanarasuth, Taworn

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