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AVAILABILITY THROUGH FIELD DEVICE DIAGNOSIS IN FEEDFORWARD CONTROL: A CASE STUDY OF FOUNDATION FIELDBUS-BASED TEMPERATURE CONTROL
(2022-02-01)
Kummool, Sart
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Suwanmanee, Ittimon
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Weerathaweemas, Songchai
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Julsereewong, Amphawan
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Sittigorn, Jirasak
For endusers, requiring an action to enable a fieldbus-based process control that is not hazardous to continue its operation in the event of transmitter failures, it is essential to understand how diagnostic capability of field instruments is helpful in availability enhancement. In order to effectively implement a feedforward control strategy with increased availability, this article presents a control configuration method when utilizing a Foundation Fieldbus (FF)-based temperature feedforward control as an illustrative case study. Four function block assignment options for configuring the studied control strategy during engineering phase are described. The ‘Uncertain’ measurement status provided by temperature transmitters is treated as ‘Good’ measurement status in all control configuration options for availability goal by reducing process downtime. In addition, based on experimental results, a simplified Petri net model for logical behavior representation of the interested FF-based feedforward is also proposed.
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Real-time dashboard monitoring and alerting system for compressed air supply in rubber compound manufacturer
(2020-01-01)
Thepmanee, Teerawat
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Ngamsangiam, Pornprasert
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Sittigorn, Jirasak
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Pongswatd, Sawai
To minimize unexpected disruptions resulting from air supply problems in manufacturing production, a continuous monitoring of air pressures is crucial for predicting and preventing significant issues that may arise. This paper proposes a technique to build a real-time dashboard monitoring and alerting system for improving an availability of existing compressed air supply in a rubber compound manufacturer in Thailand. Flow and pressure transmitters as well as motorized ball valves are installed in the ma-jor supply lines of air piping system. In addition, a 3-phase power and energy meter is also installed to measure key electrical parameters of two main air compressors. The proposed technique is based on the use of cost-effective Node-RED web application not only to monitor volumetric flow rate, air pressure values, valve statuses, input/output module statuses, and energy-related parameters on the created dashboard in real time but also to alert plant personnel to pressure readings that fall outside an acceptable range via the LINE Notify application. There are three different notification patterns depending on how long is the pressure reading value out of the acceptable range. Moreover, the on/off status of all ball valves can also be remotely set on the dashboard subpages. Experimental results verify that the improved system can be utilized to assist plant personnel in trou-bleshooting and solving the problems with compressed air supply.
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Comparative analysis between control in the host and control in the field in terms of safety and availability for foundation fieldbus-based process control
(2018-04-01)
Julsereewong, Amphawan
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Whatphat, Nopthawach
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Sangsuwan, Thaksin
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Chanwutitum, Jirasak
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Thepmanee, Teerawat
Design work of process control to provide necessary performance requirements must be based on capabilities and limitations of the technology used. This paper aims at analyzing possible safety and availability enhancements of basic process control based on Foundation Fieldbus (FF) technology in which the control function blocks can be assigned either in the host system controller, called ‘Control in the Host’ (CIH), or in the field devices, called ‘Control in the Field’ (CIF). Implementing the control loops with CIH and CIF strategies for water tank process is utilized as a case study to demonstrate the proposed analysis. The major configuration details of field devices, control strategies, and function blocks are described. Experimental results were analyzed for examining the parameter options as well as the control loop actions in response to invalid measurements to compare the safety and availability improvements between the CIH and the CIF. The proposed analysis can be useful to enable economical solutions for design phase of the FF-based control loops.
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A dynamic routing for load distribution in mobile Ad-Hoc network
(2018-01-01)
Rungtaveesak, Metha
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Chartkajekaew, Noppawit
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Thongthavorn, Thananop
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Narongkhachavana, Worrawat
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Prabhavat, Sumet
Mobile Ad Hoc Network is a group of mobile nodes which can communicate with each other directly without infrastructure device. Most conventional protocols do not consider energy on route discovery. Route breaks may occur frequently since the energy of some intermediate nodes exhausts. This interrupts the packet forwarding. In this paper, we propose load distribution algorithm based on remaining energy of nodes to prolong network lifetime and load balancing. Simulation results show that our work can increase the number of remaining nodes in the network while maintaining high packet delivery ratio.
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Petri net modeling for performance analysis of FF-based process control in terms of safety and availability enhancement
(2017-12-13)
Sangsuwan, Thaksin
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Whatphat, Nopthawach
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Chanwutitum, Jirasak
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Thepmanee, Teerawat
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Julsereewong, Amphawan
In case of device and communication failures, a basic process control using Foundation Fieldbus technology can be configured to provide either safety improvement for preventing hazards or availability enhancement for minimizing production losses. The purpose of this paper is to introduce a system modeling with Petri Net technique for representing the behaviors of the proportional-integral-derivative (PID) and cascade loops with 'Control in the Field' (CIF) and 'Control in the Host' (CIH) architectures in response to instrument and communication failures. The proposed modeling is useful for performance analysis of the interested control loops in terms of safety and availability improvement. Stakeholders of both brownfield and greenfield projects in process industry sector can select a proper solution to their necessary performance requirements.
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Safety and availability of basic process control using foundation fieldbus with control in the field - An experimental analysis
(2017-08-01)
Sangsuwan, Thaksin
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Thepmanee, Teerawat
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Julsereewong, Amphawan
Detailed knowledge of how to balance between safety and availability for instruments is essential to successful design and implementation in fieldbus-based process control systems. The configuration correctness is crucial to actually obtain the benefits of digital fieldbus technology used. In actuality, a number of device parameters must be set to provide the required functionalities. This paper focuses on improving safety and availability for the proportional-integral-derivative (PID) and cascade control strategies using Foundation Fieldbus (FF) with control in the field. The aim of this paper is to analyze the logical behaviors of PID and cascade loops in two conflicting purposes for studying how different configuration options affect the interlocks between function blocks located in instruments as well as the initialization and fail-safe mechanisms in response to invalid measurements. For safety purpose, the interested control loops are configured to bring the process to a safe state in the presence of a fault. For availability purpose, the interested control loops are configured to keep the process running in the event of a failure. A water tank process is utilized as a case study for control loop implementations. Interactions between the status propagation and mode shedding for demonstrating the studied control loop behaviors are examined experimentally in Petri net models. In addition, the function block options for bumpless transfer and setpoint tracking are also described. The proved configuration method for proper operations in balancing the interests of safety and availability is proposed.
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Measurement and simulation of equatorial ionospheric plasma bubbles to assess their impact on GNSS performance
(2012-01-01)
Tsujii, Toshiaki
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Fujiwara, Takeshi
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Kubota, Tetsunari
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Satirapod, Chalermchon
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Supnithi, Pornchai
Ionospheric anomaly is one of the major error sources which deteriorate the GNSS performance. In the equatorial region, effects of the ionospheric plasma bubbles are of great interest because they are pretty common phenomena, especially in the period of the high solar activity. In order to evaluate the GNSS performance under circumstance of the bubbles, an ionospheric scintillation monitor has been developed and installed in Bangkok, Thailand. Furthermore, a model simulating the ionospheric delay and scintillation due to the bubbles has been developed. Based on these developments, the effects of the simulated plasma bubbles are analyzed and their agreement with the real observation is demonstrated. An availability degradation of the GPS ground based augmentation system (GBAS) caused by the bubbles is exampled in details. Finally, an integrated GPS/INS approach based on the Doppler frequency is proposed to remedy the deterioration.
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Stochastic behaviour of a robot-safety device system
(1999-01-01)
Vanderperre, E. J.
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Vannakrairojn, S.
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Makhanov, S. S.
Innovations in the field of microelectronics and micromechanics have enhanced the involvement of "smart" robots in various technical applications. Unfortunately, no robot is completely reliable. Therefore, up-to-date robots are often connected with a (repairable) safety device. Such a device prevents possible damage, caused by a robot failure, in the robot's neighbouring environment. However, the random behaviour of the entire system (robot, safety device, repair facility) could jeopardize some prescribed safety requirements. Therefore, an appropriate statistical analysis is quite indispensable to support the system designer in problems of risk acceptance and safety assessments. We introduce a robot-safety device system attended by two statistically different repairmen. Our system is characterized by the natural assumption of cold standby and by an admissible "risky" state. In order to describe the random behaviour of the system, we introduce a stochastic process endowed with probability kernels satisfying Kolmogorov-type equations. The solution procedure is based on advanced methods of renewal theory. Next, we derive the invariant measure of the T-system and the long-run availability of the robot. Finally, we consider the particular but important case of fast repair.

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