Digital Control System Research Articles

Smart recoating: A digital twin framework for optimisation and control of powder spreading in metal additive manufacturing

We present a new framework for learning novel operational strategies and dynamically controlling the layering process in metal additive manufacturing. Metal additive manufacturing technologies such as powder bed fusion (PBF) are generally constrained by a fixed action powder spreading process. At every layer, the print platform is lowered by a fixed amount, and the same recoating action is performed. Ideally this would lead to consistent layering and identical properties each time, but frequently process variability disrupts this procedure, leading to inconsistent layers. This can be mitigated by intelligently controlling the powder spreading process, which we achieve via a shift to digital methodologies that can reveal new process strategies and dynamically update the printer commands. We employ Bayesian optimisation as a method to build and train surrogate models for real-time control. We then demonstrate the utility of this Smart Recoating approach within an integrated simulation framework driven by realistic Discrete Element Method powder spreading simulations. Our results inform new strategies for controlling the recoater and print stage displacements, and demonstrate the potential of a digital twin control system to mitigate process variation and achieve consistent print quality in each layer.

Experimental studies of using the digital control system in power conversion equipment of high-voltage power supply systems in spacecrafts with a hydrogen energy accumulator

Solar-hydrogen energy for spacecraft, space interplanetary stations, space bases on the planets of the solar system must reliably provide energy: spacecraft during peak periods (repairs at a space facility, energy-consuming experiments, cleaning of facilities, regeneration of waste to extract oxygen and hydrogen, etc. .d.) and bases on planets, especially where the night lasts for a long time.The onboard hydrogen module of the solar-hydrogen plant includes: a container with water; distiller; deionizer; water lines with adjustable shut-off valves; electrolyzer; cryogenic side tanks with hydrogen and oxygen; fuel cell, hydrogen safety sensor systems based on leakage and concentration sensors; level gauges; cryogenic and gas pipelines of hydrogen and oxygen; onboard cryo-refrigerator; automatic control system for the hydrogen module. The article presents the results of experimental studies of static, dynamic and mass-dimensional characteristics of power conversion equipment (hereinafter - PCE) in the power supply system (hereinafter - PSS) of the spacecraft (hereinafter - spacecraft) with a digital control system. The purpose of experimental research is to verify the theoretical results obtained earlier in the design of digital PCE control systems of high-voltage PSS spacecraft, including the study of static and dynamic characteristics. We developed and manufactured an experimental PCE sample with an output power of 2500W in this research. It includes: four voltage stabilization modules and the 100V load supply output bus filter. Each voltage stabilization module includes a battery energy conversion channel, a solar battery energy conversion channel and a digital control system unit. The power conversion channel of the accumulator battery is designed and made on the basis of a bridge volt-booster inverter-transformer circuit. Voltage control in energy converter of accumulator battery is based on phase shift in control pulses of transistors in adjustable inverter rack related to unregulated one. The power conversion channel of the solar battery is designed and made on the basis of a two-phase circuit of a direct voltage converter of an increasing type with switching throttles. The digital control system of the voltage stabilization module is designed on the basis of analogues in the modern electronic component base in the Space class and consists of four identical channels. Each channel of the control system controls its own voltage stabilization module. We obtained the following results during our experimental studies: some pulsations of the output voltage of the energy conversion equipment during operation on an active load, transient processes of the output voltage of the energy conversion equipment during pulsations of the load current without changing the mode of operation, transient processes of the output voltage of the energy conversion equipment when changing the modes of its operation and weight and size characteristics for different values of the output power. The obtained results of experimental studies confirm the previously obtained theoretical results, and also showed that the use of a distributed digital control system will increase the specific energy characteristics of the newly developed PSS spacecraft while ensuring the given static and dynamic characteristics of output voltage quality. The results of the work are designed to create a new on-board power conversion equipment for power supply systems of promising spacecraft. The area of application of the project results is space instrumentation.

Digital marketing management control system based on blockchain under the internet background

Digital marketing management control system based on blockchain under the internet background

Optimal Design and Performance Analysis of a Digitally Controlled Biogas Power Generation System Suitable for DC Microgrid

Renewable energy sources are gradually becoming an alternative to fossil fuel-based power sources. It helps in overcoming the energy crisis and minimizing the emission of toxic gases as well as ensuring a step towards achieving a carbon–neutral environment. For the uninterrupted supply of power in the area of the weak distribution of electricity, clean energy sources are proven to be a feasible solution for electrification. This work aims to design a unique concept of a biogas-fuelled power-generating system and analysis performance that can enhance renewable-based power generation. The optimization of the bio-power generation system has been carried out through the HOMER software. The power plant’s performance with a digital control system has been investigated in MATLAB at fully loaded conditions. The efficacy of the system has been validated experimentally on a hardware setup resulting in an increase in power generation efficiency of about 14%. A comparative experimental study has been presented to exhibit the benefit of the designed system over the conventional bio-power generation system like the minimization of power losses and reduced no of associated equipment as required in the conventional system. Besides that, the estimated cost of the design of the power plant and its payback period has also been investigated for a limited period of years. It has been revealed that the proposed design of the Biogas power plant and its performance is substantially efficient and can be recommended for utilization in a microgrid or any small-scale power generating system.

Ring Laser Gyros: Improving Precision and Accuracy Through Soft-Core Processor-Based Active Current Balance Control Approach- Simulation and Implementation Results

In this article, we intend to demonstrate on digital active current control in ring laser gyros (RLG). The specific source errors that effect the performance of laser gyro is discussed. This work proposes a system of digital detection and control system to address deficiencies of the conventional analog circuits. The hardware framework is constructed using the Field Programmable Gate Array (FPGA) and the required analog interface, which incorporates driving and acquisition circuitry for the specific physics of gyros. The software flow is provided in full and uses the parallel PI (proportional-integral) control algorithms. The outcomes demonstrate that the precision of anode currents are accurately controlled within ±0.1µA along with cathode voltage, demonstrating that the performance of the digital system is superior to that of analog circuits, which will be very beneficial for the laser gyro application. The simulation results prove that the proposed approach has good result of balancing anode currents, meanwhile, it makes the sensor a good dynamic performance. In both anodes, the experimental findings are contrasted with balanced and unbalanced currents. The optimal constant current is obtained from the remarkable agreement between simulated and experimental results.

Optimized Design of Source Energy for Manufacturing Machine by Digital Numerical Control

The quality of the power supplied to the machining center is a key factor in determining the accuracy of the machine’s operation. The precision of the machining center is to ensure that the spindle accuracy is less than 3 microns. This study proposes a digital numerical control system to control the quality of the power supply and control the accuracy of the spindle axis of the machining center to monitor the measurement results in real time. The computer vision system is set up according to the artificial intelligent (AI) technique to recognize human face objects and control the position of the processor respectively on each line. The online measurement system follows the digital numerical control (DNC) system applied at each processing line, measuring product dimensions, measuring conditions for setting up machining tools, and measuring machine coordinates. The system operates fully automatically, eliminating dependence on operator skill, and facilitating operation in control of machining conditions. Improve machining center operator satisfaction. After implementation of the improvement options, total cost down 1.740 USD per year, the monthly repair cost due to broken drill, spindle alignment decreased from $5000 to $3,300 per month. The scrap rate related to the hole size decreased from 0.47% to 0.23% (cost down $35 per month). Downtime for repair reduced from 20 hours per month to 7.5 hours per month (cost down $10 per month). Broken drill rate was reduced from 0.20% to 0.06% (cost down $100 per month).

Preparation and Analysis of Experimental Findings on the Thermal and Mechanical Characteristics of Pulsating Gas Flows in the Intake System of a Piston Engine for Modelling and Machine Learning

Today, reciprocating internal combustion engines are used in many branches of the economy (power engineering, machine engineering, transportation, and others). In order for piston engines to meet stringent environmental and economic regulations, it is necessary to develop complex and accurate control systems for the physical processes in engine elements based on digital twins, machine learning, and artificial intelligence algorithms. This article is aimed at preparing and analysing experimental data on the gas dynamics and heat transfer of pulsating air flows in a piston engine’s intake system for modelling and machine learning. The key studies were carried out on a full-scale model of a single-cylinder piston engine under dynamic conditions. Some experimental findings on the gas-dynamic and heat-exchange characteristics of the flows were obtained with the thermal anemometry method and a corresponding measuring system. The effects of the inlet channel diameter on the air flow, the intensity of turbulence, and the heat transfer coefficient of pulsating air flows in a piston engine’s inlet system are shown. A mathematical description of the dependences of the turbulence intensity, heat transfer coefficient, and Nusselt number on operation factors (crankshaft speed, air flow velocity, Reynolds number) and the inlet channel’s geometric dimensions are proposed. Based on the mathematical modelling of the thermodynamic cycle, the operational and environmental performance of a piston engine with intake systems containing channels with different diameters were assessed. The presented data could be useful for refining engineering calculations and mathematical models, as well as for developing digital twins and engine control systems.

Design and Simulation-Based Optimization of an Intelligent Autonomous Cruise Control System

Significant progress has recently been made in transportation automation to alleviate human faults in traffic flow. Recent breakthroughs in artificial intelligence have provided justification for replacing human drivers with digital control systems. This paper proposes the design of a self-adaptive real-time cruise control system to enable path-following control of autonomous ground vehicles so that a self-driving car can drive along a road while following a lead vehicle. To achieve the cooperative objectives, we use a multi-agent deep reinforcement learning (MADRL) technique, including one agent to control the acceleration and another agent to operate the steering control. Since the steering of an autonomous automobile could be adjusted by a stepper motor, a well-known DQN agent is considered to provide the discrete angle values for the closed-loop lateral control. We performed a simulation-based analysis to evaluate the efficacy of the proposed MADRL path following control for autonomous vehicles (AVs). Moreover, we carried out a thorough comparison with two state-of-the-art controllers to examine the accuracy and effectiveness of our proposed control system.

Modelling of Catechin Extraction from Red Grape Solids under Conditions That Simulate Red Wine Fermentation

Digital control systems are well established in many industries and could find application in the wine sector. Of critical importance to red wine quality, the efficient and targeted extraction of polyphenols from red grape solids during alcoholic fermentation could be a focus for automation. Smart technologies such as model predictive control (MPC) or fuzzy logic appear ideal for application in a complex process such as wine polyphenol extraction, but require mathematical models that accurately describe the system. The aim of this study was to derive and validate a model describing the extraction of catechin (a representative polyphenol) from red grape solids under simulated fermentation conditions. The impact of ethanol, fermentable sugar, and temperature on extraction rate was determined, with factor conditions chosen to emulate those present in industry practice. A first-order approach was used to generate an extraction model based on mass conservation that incorporated temperature and sugar dependency. Coefficients of determination (R2) for all test scenarios exceeded 0.94, indicating a good fit to the experimental data. Sensitivity analysis for the extraction rate and internal cross-validation showed the model to be robust, with a small standard error in cross-validation (SECV) of 0.11 and a high residual predictive deviation (RPD) of 17.68. The model that was developed is well suited to digital technologies where low computational overheads are desirable, and industrial application scenarios are presented for future implementation of the work.

Qualification and impact of a video-assisted control system in a chemotherapy compounding unit

ObjectivesAnticancer drug preparation control is essential to ensure quality and patient safety. Drugcam (Eurekam Company) is a digital video-assisted control system based on artificial intelligence methods to identify vials used...

CNS: Research on Data Security Technology and Network Data Security Regulations Driven by Digital Economy

In order to improve data security and network data security in the digital economy-driven environment, this paper combines data security technology and network security technology to build a digital economy security management and control system. Moreover, this paper describes the data encryption of the data owners before the framework index and the composition and construction method of the corresponding EncIR tree, and analyzes the spatial keyword group query algorithm on the EncIR tree. In addition, this paper analyzes the experimental performance of index building and spatial query, and builds an intelligent digital economy security system on the basis of these algorithms. The experimental research results verify that the data security technology and network data system driven by the digital economy have good security performance, and on this basis, follow-up security regulations can be formulated.

Cyber Threats and Nuclear Weapons by Herbert Lin

Nuclear weapons are a throwback to the analog age. This is a good thing because in the digital era, air-gapped, nuclear command, control, and communication systems operating with antiquated software and hardware are resistant to today's internet-enabled cyber threats. As Herbert Lin notes in this brilliant little book, however, the safety, security, and surety inherent in the analog nuclear complex is eroding as the digital revolution overtakes just about every aspect of scientific, technological, commercial, and social life. By exploring the nuclear complex as a system and across the life-cycle of its various components, Lin illustrates how cyber context (the growing presence and interaction of digital systems) and cyber operations (digital attacks intended to compromise computer systems and the humans that operate them) threaten the integrity of a nuclear arsenal in a myriad of ways. Officers and officials can do little to arrest this trend. Dealing with the growing presence of Information Age technology in the nuclear complex creates a series of dilemmas that can never be fully resolved by designers, manufacturers, and operators. Every component in the nuclear complex—delivery systems, communications, sensors, and nuclear weapons themselves—can be compromised if actors can manage to incorporate malware or unauthorized hardware into the manufacturing process. It is possible to limit this threat, but such measures increase costs while decreasing capability and ease of operation. This pattern emerges when it comes to mitigating cyber threats against each component and function of the nuclear complex.

Design and Suitability Analysis of FPGA-Based TCP/IP Offload Module for Control Systems of FBRs

Transmission Control Protocol/Internet Protocol (TCP/IP) offload modules play a crucial role in India’s first commercial fast breeder reactor (PFBR) distributed digital control system architecture by providing networking capabilities to the real-time control systems used in safety-critical and safety-related applications of the PFBR. These modules enable operators to remotely control various mechanisms, facilities, and process loops via real-time control systems from the main control room display stations. The malfunctioning of these modules may hamper the overall plant’s availability; hence to improve further upon safety, security, reliability, and performance, these modules have been indigenously developed for upcoming fast breeder reactors in India. This paper proposes methods to justify the suitability of these communication modules as per the D-25 design guidelines issued by the Atomic Energy Regulatory Board of India. The design and testing aspects are covered, including an approach toward hardware descriptive language-based design and testing with respect to the IEEE standard and the TCP/IP protocol specifications. Module design validation based on ethernet frame transactions is detailed in this paper. The test platform design, which includes the diagnostics software design for CPUs designed with these TCP offload modules, and the design of a graphical user interface to detect and record TCP connection anomalies are detailed. The network interface response to postulated events of TCP packet corruption, packet drop, packet delay, out-of-order packets, duplicate packets, and heavy traffic is characterized.

Controller Design in <i>αβ</i> domain for Grid-Forming Inverters by Complex Vector Theory

Grid-forming inverter control plays an important role in ensuring frequency and voltage stability in a microgrid (MG). This paper proposes a novel power and voltage control in the αβ domain. The proposed method includes two control loops; an outer loop for power droop control and an inner loop for output voltage control. With the proposed controller, active and reactive powers can be controlled according to simple complex power control principles described only in the αβ-domain. Controller gain tuning for both the outer droop and the inner voltage regulator is also proposed; the droop control gains are tuned based on transfer functions around an operating point and the voltage regulator is tuned by a linear quadratic regulator (LQR). The proposed control method is investigated and validated by simulations with a C control program and by experiments with a DSP-based digital control system.

ALGORITHMIC METHODS FOR DEVELOPING THE STRUCTURE OF A THYRISTOR ELECTRIC DRIVE FOR MINING MACHINES

The article discusses the creation of algorithmic structures and the development of digital control systems for electric drives of mine-lifting machines, provides some concepts for creating digital control systems using thyristor converters. The analysis of the static volt-ampere characteristics of the thyristor is given, some calculations of the circuits and circuits of the thyristor converter (TP) corresponding to the different modes of operation of the TP are given, and also, based on the synthesis of the dynamic properties and characteristics of the thyristor, an algorithmic structure of the model of the thyristor converter is proposed.

Availability analysis of safety-critical systems of nuclear power plant using ordinary differential equations and reachability graph

With the growing advancement and demand for technology, computer-based systems (CBS) have become an integral part of human life. Numerous CBSs are safety and mission-critical in nature, and are employed in various industries, including nuclear power plant (NPP), locomotive control, avionics, medical automation, etc. Safety-critical systems (SCS) are one such CBS that are vital to control and maintain the infrastructure of NPP. This paper presents an inventive technique to assess the performance metric availability of SCSs. A Petri net (PN) models such systems, which feature multiple processing nodes interacting with one another. PN models are useful for generating the reachability graph. This article uses reachability graph to derive a collection of ordinary differential equations (ODEs), whose solution can be applied for assessing the availability of the system. Conventional methods like Markovian chains, Reliability Block diagrams (RBDs), Fault Tree Analyses (FTAs), and Flow Networks fail to cover the systems' behaviors and structures properties, as well as the lack of failure data, and the diversity of possible failures. The suggested technique has been applied to Digital Feed Water Control System (DFWCS) of NPP, which consider the failure, maintenance and repairment of the main-steam safety valves. We achieved 99.20% accuracy of availability measurement, proving the efficacy of methodology.

Designing Digital COVID-19 Screening: Insights and Deliberations.

Due to the global COVID-19 pandemic, public health control and screening measures have been introduced at healthcare facilities, including those housing our most vulnerable populations. These warning measures situated at hospital entrances are presently labour-intensive, requiring additional staff to conduct manual temperature checks and risk-assessment questionnaires of every individual entering the premises. To make this process more efficient, we present eGate, a digital COVID-19 health-screening smart Internet of Things system deployed at multiple entry points around a children's hospital. This paper reports on design insights based on the experiences of concierge screening staff stationed alongside the eGate system. Our work contributes towards social-technical deliberations on how to improve design and deploy of digital health-screening systems in hospitals. It specifically outlines a series of design recommendations for future health screening interventions, key considerations relevant to digital screening control systems and their implementation, and the plausible effects on the staff who work alongside them.

A novel hydraulic load-sensing control solution to working functions of mobile machine

The hydraulic load-sensing system is a more efficient system solution than constant pressure system in mobile machine. However, the overall system efficiency for multiple actuators is still low since this centralized hydraulic control system only adapts to the highest load pressure. Therefore, in this article, a distributed hydraulic control system where each function is powered by a hydraulic free piston engine is proposed. Compared with centralized solution, it is more efficient since the power of hydraulic free piston engine is tailored to each function. By integrating small inertia linear engine and pump piston in one unit, the hydraulic free piston engine is an efficient and fast response hydraulic power source. Since the hydraulic free piston engine is essentially a digital hydraulic power source, a digital load-sensing control is proposed in this study. The system architecture, modeling, controller design and performance of the digital hydraulic load-sensing control system are presented. A test bench is developed to verify the system feasibility and performance.

Commissioning and first operational experience with the new thyristor converter Group 7 of ASDEX Upgrade

Due to the continuously expanding experimental program of ASDEX Upgrade (AUG), the high current converters came to their limits. At the same time, the risk of failure increased because of the equipment aging. In order to reduce this risk and to extend the area of operation, a new thyristor converter called “Group 7″, equipped with a recently developed digital control system, was installed. While the design was already published on SOFT 2018, this paper will describe in detail the commissioning results and the first operational experience of the new thyristor converter. The manufacturing and on site installation of Group 7 started in 2018 and was finished in spring 2021 by the delivery of the transformers. In parallel to the construction process the main components were type-tested. One of four converter modules was extensively verified during the factory acceptance tests. In order to be able to test the digital control system independently of the construction of the power converter, a scale model was built. All functions of the control system were tested on it. It was also useful to investigate the problems arising during commissioning and to verify firmware fixes. After finishing the site installation work, the converter was proved in all possible configurations on a test coil. These tests were performed in local and remote control. Attention was also paid to the effect of power factor improvement by neutral-point vs. regular bridge (B6) thyristor configuration. For this reason, all tests were performed with and without operation of the neutral-point thyristors. The last step was to operate the converter on the magnet coils of AUG. In an intensive test program over a period of six month, all poloidal field and OH coils of AUG were operated with the new converter in the required operation mode.

Design and Implementation of a Digital Control System for Lead Acid Battery Charging

Ensuring a long battery life and satisfactory performance requires accurate charging cycles. There are three phases to the charge cycle - Constant Current Charge, Constant Voltage Charge, and Float Charge. It is usual that lead acid battery users complain about fast degrading performance because most the low cost commercially available lead Acid Battery chargers provides only single-stage charging phase which is that of constant-voltage charging phase. To ensure long service life and good performance, it is of paramount importance that all charging modes are respected. This said it is clear that the battery charger should have a certain degree of controllability over voltage and current quantities through-out the charging process. In this paper, we designed and built a lead acid battery charger to use in conjunction with a synchronous buck converter topology. After implementing and testing the system, we obtained good results in both the quantitative and qualitative analysis of the implemented system tested, a 12 V- 7000mAh battery. With the help of a MCU-based digital control system containing two different control transfer functions - constant current Feedback Control and Constant Voltage Feedback Control monitoring the charging process proved possible without any overshoot. The prototype showed us an efficiency rating of 86.60%, the maximum error level was recorded at 0.05V, and there were no problems related to overshoot or transient response when testing our prototype which worked flawlessly.