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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
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Kasuya, Sanshiro
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Oba, Yojiro
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Okada, Takuya
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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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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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Aircraft Altitude Control Based on CDM
(2019-05-09)
Asa, Ekachai
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Yamamoto, Yoshio
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Benjanarasuth, Taworn
This research presents the controller design for aircraft altitude control based on Coefficient Diagram Method (CDM). The controller, which is designed by CDM, guarantees a good balance of stability, response and robustness. The simulation results of the proposed control system show that the controller is able to control the aircraft altitude as desired and has a disturbance rejection behavior and the response speed can be easily adjusted by specification of the equivalent time constant. As the result, the controller design processes are less complex than other methods and the controller is still effective.
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Experimental study of influence of message length on communication accuracy using beverage plant simulator
(2018-08-13)
Phirawitsuphamon, Phimnada
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Takakashi, Makoto
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Karikawa, Daisuke
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Benjanarasuth, Taworn
This study concerned the influences of message length on communication errors caused by human. Based on a beverage plant scenario and developed simulator, experiments were conducted to better understand the relation between the number of instructions and the occurrence of communication errors. The results confirmed that the less the number of commands in a message, the less the communication errors but the longer the used time.
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A heated needle micromanipulator with hybrid control for heat-caused denaturation in proteins
(2015-08-25)
Boksuwan, Sungwan
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Benjanarasuth, Taworn
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Aoyama, Hisayuki
The paper proposes a micromanipulator with the heated needle as an end effector in order to transfer heat around a micro area of a sample, egg whites. The proposed micromanipulator is controlled by a combination of an explicit model predictive control and PID controller, so-called the hybrid control, to accomplish tracking performances of several reference paths or shapes of heating the specific area. A tungsten needle wrapped with nichrome wire is used as a heat source mechanism and is connected to the two dimensional micromanipulator. The experimental results reveal that the heated needle can provide high temperature up to 50°C with 10μm needle tip diameter. In addition, the results indicate the effective operations for a point heating and denaturing egg whites in micro scale. Moreover, the heated needle is able to heat along the desired paths (a circle, ellipse, square or triangle) with the error less than 2μm from the center of measurement.
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Tremor suppression for handheld micromanipulator using robust hybrid control
(2014-12-16)
Boksuwan, Sungwan
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Benjanarasuth, Taworn
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Kanamori, Chisato
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Aoyama, Hisayuki
This paper proposes a suppression of tremor effects, fluctuations caused by a user's hand, on a handheld micromanipulator by means of a robust hybrid control scheme. The proposed control scheme is a combination between an explicit model predictive control and a PID controller. The advantage of the PID controller is a robustness. It is suitable for handling the holding angle changes. The explicit model predictive control provides the excellent tracking performance. In addition, the robust hybrid control can handle tremor effects successfully. The control objective is to achieve robust tracking performance, to dampen the vibration of the mechanism and to suppress a disturbance, a tremor. The experimental results are used to investigate the effectiveness of the proposed method.
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Robust hybrid control for two-dimensional handheld micromanipulator
(2014-01-01)
Boksuwan, Sungwan
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Benjanarasuth, Taworn
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Kanamori, Chisato
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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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Robust real-time model predictive control for torsional vibration system
(2012-01-01)
Boksuwan, Sungwan
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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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Parameters tuning effects in the model predictive control of an inverted pendulum
(2011-12-01)
Chunhacha, Pongtorn
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Benjanarasuth, Taworn
This paper investigates the applicability of using model predictive control for an inverted pendulum system and observes its parameters tuning effects. The linear model predictive control under an input saturation constraint is applied to the nonlinear model of the inverted pendulum on cart system. Sampling period and prediction horizon are varied for investigating their influences to the system's stability and performance. The comparison between the linear quadratic regulator and the model predictive control with the same weighting matrices is additionally implemented. © 2011 IEEE.
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IMC-based PID controllers design for a two-links SCARA robot
(2011-12-01)
Suvilath, Sipaseuth
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Khongsomboun, Khamphong
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Benjanarasuth, Taworn
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Komine, Noriyuki
The paper presents the design of PID controllers for a two-link SCARA robot based on internal model control (IMC) technique. For the model of the two-link SCARA robot which includes an integrator, IMC filter must be selected properly so that the designed IMC controllers can be approximated as PID controllers by using Maclaurin approximation. The simulation results verify the applicability and satisfied performance of the proposed control system. © 2011 IEEE.

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