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"Programmable logic controllers"
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PLC and SCADA based temperature control of heat exchanger system through fractional order PID controller using metaheuristic optimization techniques
SCADA systems play an important role in tracking the behaviour of critical process variables and connecting geographically dispersed subsystems at the industrial plant level. This article presents a PLC and SCADA-based control framework to automate and supervise the temperature control processes in the heat exchanger plant. The OMRON (NX1P2-9024DT1) PLC is interfaced with the Wonderware InTouch SCADA system to gather data, create a simulated temperature control prototype and carry out the necessary control operations within the heat exchanger plant. The PLC controls the entire process and programming of PLC is done using Sysmac studio automation software using the ladder programming language. The proposed system controls the temperature of the heat exchanger system through PID and Fractional Order PID (P
I
λ
D
μ
) controllers with Integral Anti-windup technique. Various control strategies like Cascade Control, Feedforward Control and Smith Predictor for time delayed process are discussed for controlling the temperature of the process. The performance of both PID and fractional order PID controllers is optimized using adaptive heuristic optimization techniques like Genetic Algorithm (GA), Ant Colony Optimization (ACO) and Particle Swarm Optimization (PSO). In control system design and analysis, the calculated performance indices are used as quantitative measures for evaluating the performance of a system. The combined form of temperature controller with Cascade control, Feedforward control and dead-time compensator is modelled and examined for simulation using MATLAB. Simulation and real-time experimentation analysis of the developed controllers are executed with metaheuristic optimization techniques based on different performance indices like ISE, IAE and ITAE.
Journal Article
Petri net models of discrete logics used in control algorithms developed in ladder diagram language
Control algorithms for programmable logic controllers are still developed based on the experience of those responsible for control in the industry. The IEC-61131-3 standard considers five programming languages: Ladder Diagram, Structured Text, Function Block Diagram, Instruction List, and Sequential Function Diagram, which use different function blocks to develop control algorithms. Within the control algorithms for discrete event systems, there are two types of blocks: those with discrete inputs and outputs, and those with discrete and analog inputs and discrete output. Of the latter, the present research shows the analysis and formal model of the blocks including the problems of accumulation of tokens and the restoration of the coils. This proposal includes logical blocks of timers, counters, positive and negative transition detectors and bistable elements, which, together with the AND, OR, AND-OR, contact lock, auto-loop and Set-Reset logics, can be modeled and analyzed control algorithms with a greater degree of complexity. This guarantees the safety of workers as well as machines.
Journal Article
Efficiency improvement of automated production line by conversion of subroutine configuration
Programmable control for automated production is an essential technology for industrial development. In addition, a flexible main control system and scheduling management can significantly improve production efficiency. This study improved a programmable logic controller (PLC) subroutine module and communication methods using the modular production system (MPS) automated workstation developed by Festo to optimize the process of production. First, a simulated production line with feeding, transportation, discrimination, and processing stations was set up in a laboratory. Experiments and tests were performed, and data were collected. Consequently, different program editing and planning methods, such as program modularization, step system, and subroutines of the busbar, were proposed for PLC and automation systems. The design with clearer and more modularized subroutines was used to improve the production line performance and stability and achieve dynamic scheduling to optimize the production line efficiency to meet the demands.
Journal Article
An Automatic Fluid Filling Mechanism Using Delta PLC
This project is carried out using Programmable Logic Controller, which is the main component of the proposed system. It is an industrial oriented machine system used to fill water in the empty bottles automatically, which reduce the usage of man power, low power consumption, accuracy. The system is implemented in various soft drink industries, water packaging industries and food industries. The filling process gets efficient, when our filling machine is combined with an automatic conveyor to increase the speed of filling process. The conveyor belt roll-up the empty bottles and an analog timer is used to adjust the timing of the water flow. The empty bottles are sensed by photo electric sensors and it detects the empty bottles present in the conveyor, stops the conveyor, then the valve is opened up to fill the bottles. This sequential process will continue for each and every water bottle filling process. A Programmable Logic Controller machine is preferred due to its and cost efficient high ratings. The proposed method will reduce the cost for small scale industries and help them in setting up and an automated decision for filling water bottles.
Journal Article
Automatic berthing control under wind disturbances and its implementation in an embedded system
This paper proposes a practical algorithm and its implementation of automatic berthing in wind disturbances environments. Berthing operation is one of the most complex tasks for seafarers. Automation of the highly burdensome berthing maneuver can be used to assist seafarers. In this study, we analyze the effect of wind disturbance on path following and propose a new path following control algorithm using a 2-DoF controller that introduces a feed-forward control. We also propose a method to reduce path deviation by introducing a runway in path planning. The effectiveness of the proposed method is verified by numerical simulations and shipboard tests using an experimental ship, and the proposed method shows higher performance under wind disturbance than the previous methods. The algorithm verified in this study is implemented as a PLC system, AutoBerth PLC. A PLC is an industrial computer, stable in operation. Using the AutoBerth PLC, we conducted an experiment of automatic berthing by an actual ship and confirmed that the system can be controlled faster and more stable than when controlled by a laptop. To realize a practical system, an alert function for the ODD, an alert function for fallback response regarding self-diagnosis of PLCs and communication monitoring functions were implemented as required functions in a maritime autonomous surface ship (MASS), and these functions were verified on the experimental ship.
Journal Article
A Flashback on Control Logic Injection Attacks against Programmable Logic Controllers
Programmable logic controllers (PLCs) make up a substantial part of critical infrastructures (CIs) and industrial control systems (ICSs). They are programmed with a control logic that defines how to drive and operate critical processes such as nuclear power plants, petrochemical factories, water treatment systems, and other facilities. Unfortunately, these devices are not fully secure and are prone to malicious threats, especially those exploiting vulnerabilities in the control logic of PLCs. Such threats are known as control logic injection attacks. They mainly aim at sabotaging physical processes controlled by exposed PLCs, causing catastrophic damage to target systems as shown by Stuxnet. Looking back over the last decade, many research endeavors exploring and discussing these threats have been published. In this article, we present a flashback on the recent works related to control logic injection attacks against PLCs. To this end, we provide the security research community with a new systematization based on the attacker techniques under three main attack scenarios. For each study presented in this work, we overview the attack strategies, tools, security goals, infected devices, and underlying vulnerabilities. Based on our analysis, we highlight the current security challenges in protecting PLCs from such severe attacks and suggest security recommendations for future research directions.
Journal Article
A smart PLC-SCADA framework for monitoring petroleum products terminals in industry 4.0 via machine learning
The paper introduces a Programmable Logic Controller (PLC) / Human Machine Interface (HMI) system incorporated along with machine learning (ML) classifiers. Although some other studies have incorporated ML techniques to predict and control petroleum product terminals in terms of concentration, the proposed framework incorporates Add On Instruction (AOI) programming, PLC, and ML methods to automatically monitor petroleum products terminals. The framework adds an AOI in programming to achieve maximum usage of processor capabilities. Moreover, it uses AOI for programming in cooperation with the ladder diagram (LD). This leads to simplifying the LD graphical programming language, reducing the time of scanning, and making facilitate troubleshooting. The AOI is merged with ML to automate tank level detection and maintain good operational conditions and consequently protect these expensive essential assets. The introduced framework consists of three stages. The first stage is the PLC programming phase where the PLC is created using Add-On instructions. Next, HMI graphic displays are drawn and linked to the PLC tags in the following stage. During the third stage, the actual process readings are applied to the system based on ML algorithms to test its functionality. The proposed system results indicates a reduction in the LD number, highest program size, and maximum time of scanning. The results indicate that the AOI can help to trace the program more easily in fault situations. Besides, additional program instructions could reduce processor memory, system construction costs, and upgrade projects.
Journal Article
Personal computer/programmable logic controller based variable frequency drive training platform using WxPython and PyModbus
Variable frequency drive (VFD) is one of the key elements in industrial field. It is used to match the three-phase induction motor’s speed and torque to the industrial field process requirements in addition to energy saving and efficiency improvement. This important role of the VFD asks for the development of an efficient training and cost effective platform for the electrical engineering students, technicians, and maintenance personals. This paper introduces a user-friendly platform through which the users can understand and practice the configuration of the various parameters of the VFD unit. This platform uses two computing devices to deal with the VFD; these are the personal computer (PC) and the programmable logic controller (PLC) which is also a computer but designed to operate in wide range of temperature and humidity and can accept digital and analog signals. The PC uses WxPython (cross-platform graphical user interfaces (GUI) toolkit of Python programming language) and PyModbus communication utility to play the role of the human machine interfacing (which allows the user to execute the communication requirements and at the same time provide an oscilloscope like facility to display the platform response in real time mode or history recorded mode). With this platform, the VFD’s parameters configuration is done via the RS-485 communication port using Modbus recommandation temporaire d'utilisation (RTU) communication protocol.
Journal Article
Aye: A Trusted Forensic Method for Firmware Tampering Attacks
The Programmable Logic Controller (PLC) is located at the junction of the virtual network and physical reality in the Industrial Control System (ICS), which is vulnerable to attacks due to its weak security. Specifically, firmware tampering attacks take the firmware under the PLC operating system as the primary attack target. The firmware provides the bridge between PLC’s hardware and software, which means tampering against the firmware can be more destructive and harmful than other attacks. However, existing defense and forensics methods against firmware tampering attacks are asymmetrical, which directly leads to the proliferation of such attacks and the difficulty of forensic tracing. How to accurately, quickly, and efficiently conduct forensics for such attacks is an urgent problem. In this paper, we designed and implemented a reliable detection method based on Joint Test Action Group (JTAG) and memory comparison—Aye, which can detect mainstream firmware tampering attacks reliably. To determine the effectiveness and reliability of Aye, we selected a widely used PLC to observe Aye’s performance in defense and forensics by simulating the two latest PLC firmware tampering attack methods. The experimental results show that Aye can effectively defend against firmware tampering attacks, helping improve the efficiency and accuracy of such attack detection and forensics.
Journal Article