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.
Abstract
Kiln is a kind of main heat consuming equipment built with refractory materials to calcine materials and products. The temperature control of kiln directly affects the efficiency of the ...system, product quality and output. In order to produce the desired product output and quality, the kiln temperature must be controlled within a certain range to meet the process requirements. Due to the uncertainty and large lag of kiln temperature, the traditional control can not guarantee the constant temperature. Now taking the kiln temperature as the research object, the PID control based on PLC controller is adopted for the temperature. The results show that the PID kiln temperature control based on PLC has ideal effect and wide application prospect.
Probabilistic inference from real-time input data is becoming increasingly popular and may be one of the potential pathways at enabling cognitive intelligence. As a matter of fact, preliminary ...research has revealed that stochastic functionalities also underlie the spiking behavior of neurons in cortical microcircuits of the human brain. In tune with such observations, neuromorphic and other unconventional computing platforms have recently started adopting the usage of computational units that generate outputs probabilistically, depending on the magnitude of the input stimulus. In this work, we experimentally demonstrate a spintronic device that offers a direct mapping to the functionality of such a controllable stochastic switching element. We show that the probabilistic switching of Ta/CoFeB/MgO heterostructures in presence of spin-orbit torque and thermal noise can be harnessed to enable probabilistic inference in a plethora of unconventional computing scenarios. This work can potentially pave the way for hardware that directly mimics the computational units of Bayesian inference.
Programmable logic controllers (PLCs), i.e., the core of control systems, are well-known to be vulnerable to a variety of cyber attacks. To mitigate this issue, we design PLC-Sleuth , a novel ...noninvasive intrusion detection/localization system for PLCs, which is built on a set of control invariants-i.e., the correlations between sensor readings and the concomitantly triggered PLC commands-that exist pervasively in all control systems. Specifically, taking the system's supervisory control and data acquisition log as input, PLC-Sleuth abstracts/identifies the system's control invariants as a control graph using data-driven structure learning, and then monitors the weights of graph edges to detect anomalies thereof, which is in turn, a sign of intrusion. We have implemented and evaluated PLC-Sleuth using both a platform of ethanol distillation system (EDS) and a realistically simulated Tennessee Eastman (TE) process. The results show that PLC-Sleuth can: 1) identify control invariants with 100%/98.11% accuracy for EDS/TE; 2) detect PLC intrusions with 98.33%/0.85 ‰ true/false positives (TPs/FPs) for EDS and 100%/0% TP/FP for TE; and 3) localize intrusions with 93.22%/96.76% accuracy for EDS/TE.
Abstract
Automation is preferred in every production and service field to reduce human intervention to achieve high efficiency, reliability and less human effort. In this paper the design of a smart ...coffee maker is implemented using a Programmable Logic Controller (PLC). The proposed coffee machine includes eight different modes that offer hot drinks ranging from black coffee to white tea depending on the user’s input. Because of its durability and ease of installation and maintenance, the proposed Smart Coffee Maker system includes a PLC controller. Furthermore, the PLC monitors the input on a regular basis, and the actuators utilized in the project, such as the conveyor belt, various valves, and the lamp, are controlled based on the input and custom program downloaded in the PLC to achieve the automation of the coffee making process. Toggle switches are used to select the appropriate mode, while limit switches are used to assure the operation sequence by functioning as a control signal/input to turn the conveyor belt motor ON/OFF. The smart coffee maker technology has been tested in the laboratory and has shown to be effective.
In this paper, we propose a complex structure of Stewart platform, in 3-RSS configuration, for high precision elevator tasks. After defining the dynamic model based on the Lagrange method, we present ...the simulation studies concerning the system movement ability. Thereafter, based on the theoretical analysis and considerations, we design and construct a real-life object. The obtained verification tests of the system confirm its applicability in industrial automation and robotics system.
Fractional-order control system design can be used for systems with non-local dynamics involving long-term memory effects. However, implementation of a fractional-order controller in industrial ...systems is complicated, because of the excessive demand for computational power. The following paper presents the step-by-step design procedure, parameter tuning, and experimental evaluation of the fractional order proportional-integral-derivative (FOPID) controller. The control algorithm is based on the Continued Fraction Expansion approximation of the fractional-order operators. It is implemented on a standard industrial Programmable Logic Controller. The FOPID control system is verified and evaluated in terms of efficiency and robustness using a new laboratory benchmark of a temperature control in the pipeline. The proposed solution shows increased efficiency in terms of robustness compared to the standard PID closed-loop control.
SDN Controllers Zhu, Liehuang; Karim, Md M.; Sharif, Kashif ...
ACM computing surveys,
02/2021, Letnik:
53, Številka:
6
Journal Article
Recenzirano
Software-defined networks offer flexible and intelligent network operations by splitting a traditional network into a centralized control plane and a programmable data plane. The controller in the ...control plane is the fundamental element used to manage all operations of the data plane. Hence, the performance and capabilities of the controller itself are essential in achieving optimal performance. Furthermore, the tools used to benchmark their performance must be accurate and useful in measuring different evaluation parameters. There are dozens of controller proposals for general and specialized networks in the literature. However, there is a very limited comprehensive quantitative analysis for them. In this article, we present a comprehensive qualitative comparison of different SDN controllers, along with a quantitative analysis of their performance in different network scenarios. We categorize and classify 34 controllers and present a qualitative comparison. We also present a comparative analysis of controllers for specialized networks such as the Internet of Things, blockchain networks, vehicular networks, and wireless sensor networks. We also discuss in-depth capabilities of benchmarking tools and provide a comparative analysis of their capabilities. This work uses three benchmarking tools to compare 9 controllers and presents a detailed analysis of their performance, along with discussion on performance of specialized network controllers.
Stealthy attacks manipulate the operation of Industrial Control Systems (ICSs) without being undetected, allowing persistent manipulation of system operation and thus the potential to cause ...destructive damage. This paper introduces a new vulnerability of ICS that can be exploited to mount stealthy attacks without requiring any domain knowledge. This vulnerability is caused by a common practice in system monitoring, i.e., the SCADA monitors ICS operation at a much lower frequency than system execution, causing a loss of precision when the SCADA tries to cross-validate the issued control commands using the collected sensory data. Exploiting this vulnerability, an attack called PLC-SAGE is designed to stealthily manipulate the system operation by identifying and injecting malicious control commands that will not be concluded as abnormal by the SCADA. This paper further discusses a preferred ICS engineering practice and an attestation strategy to mitigate the above vulnerability and protect ICS from PLC-SAGE . Both PLC-SAGE and the proposed mitigations have been experimentally validated on two ICS platforms.
The reconfigurable intelligent surface (RIS) has been recognized as an essential enabling technology for sixth-generation (6G) mobile communication networks. An RIS comprises a large number of small ...and low-cost reflecting elements whose parameters can be dynamically adjusted with a programmable controller. Each of these elements can effectively reflect a phase-shifted version of the incident electromagnetic wave. By configuring the wave phases in real time, the propagation environment of the information-bearing signals can be dynamically manipulated to enhance communication reliability, boost transmission rate, expand cellular coverage, and strengthen communication security. In this study, we provide an overview on RIS-assisted wireless communications. Specifically, we elaborate on the state-of-the-art enabling techniques for the RIS technology as well as their corresponding substantial benefits from the perspectives of RIS reflection and RIS modulation. With these benefits, we envision the integration of RISs into emerging applications for 6G. In addition, communication security is of unprecedented importance in future 6G networks with ubiquitous wireless services in multifarious verticals and areas. We highlight potential contributions of RISs to physical-layer security, in terms of secrecy rate and secrecy outage probability, exemplified by a typical case study from both theoretical and numerical aspects. Finally, we discuss challenges and opportunities on the deployment of RISs in practice to motivate future research.
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