A Method for Assessing the Stability of Digital Automatic Control Systems (ACS) with Discrete Elements. Hypothesis and Simulation Results

This paper investigates the fuzzy control method for the linear switched reluctance motor (LSRM) drive system. Modeling of the LSRM is constructed based on the finite element method (FEM) environment Maxwell and the control system is analyzed by the co-simulation environment with Simplorer. Both the performance of the fuzzy proportional integral differential (PID) controller and the traditional PID controller are compared. The simulation results prove that the fuzzy PID controller yields faster rising time and smaller overshoot, compared with the traditional PID controller.

The Automatic Train Control (ATC) system was originally developed to support safe, super-high speed railway transport on Japan's Shinkansen network. East Japan Railway Company has developed a new Shinkansen ATC that utilizes digital communications and control (DS-ATC). The DS-ATC system controls train speed mainly relying on the onboard equipment allowing a reduction in rail-side devices, enhancing passenger riding comfort, and reducing arrival times and intervals between trains. This paper describes the architecture, functions, train braking process, merits of the digital ATC, and DS-ATC implementation schedule.

The insertion of communication networks in closed-loop of digital control systems makes the system synthesis and analysis complex. In this paper, we consider the combination of classical reliability, risk and safety evaluation with typical control system through digital networked control systems. The main purpose is to study the influence of transmission delays and packet dropouts on the reliability of digital networked control systems by using a modified statistical method-Monte Carlo simulation. The behaviors of two types of fault are modelled by different statistical distribution. The control strategies we apply for digital control systems are Proportion Integration Differentiation control strategies, generated by Genetic Algorithm. In terms of a realistic system model, we evaluate and compare the influences on the reliability of digital networked control systems with different control strategies from quantitative aspect. Numerical examples are presented to illustrate the effectiveness and correctness of the approach.

The series of IEC 61850 standards is currently the most widely used source for description of a digital substation’s equipment and processes; therefore, advanced technologies in the field of designing relay protection and automatic controls (PAC) shall inevitably be developed in compliance with the requirements of these standards. However, the scope of this standard series was originally limited to describing SCADA-controlled facilities and processes, which poses certain restrictions on the standard series capabilities. PAC systems should be designed subject to the IEC 61850 requirements, but at the same time, the IEC 61850 standard does not provide any tools and has no intent for thoroughly describing the structure and operational principle of PAC devices, and only describes the external interface for monitoring the necessary data, which is sufficient from the SCADA system perspective. Such restrictions of the standard series can be clearly seen when it comes to designing centralized PAC systems, PACs with migrating functions and digital substation computer-aided designing and monitoring systems, which pose more stringent (compared to a SCADA) requirements for describing the information model structure and for data exchange between its parts. The fact that the actual algorithmic support of the PAC functions differs from their information models has an impact on designing the functional requirements for logic units (LU). The functional requirements for LUs cannot be developed unless there is understanding of the logical device (LD) structure that will reflect a certain function; however, IEC 61850 does not specify any logical device structure. As a result, both the structure of logical devices and the functions implemented within one LU may differ essentially from manufacturer to manufacturer, which has a negative impact on the compatibility of the solutions offered in the market. The development of logical devices and units within the research framework revealed a number of problems connected with the specific features of implementing IEC 61850, which result in lack of unambiguity of LU and LD implementations. Thus, the standard does not specify the sources of signals supporting the LU operation, nor does it consider a functional for processing and producing measurements for relay protection as part of the information model. The standard does not describe the functions typical for the domestically adopted PAC designing practice. It should also be noted that the UES Federal Grid Company’s corporate profile specifies them only partially since it inherits the description structure from IEC 61850. The article suggests a change in the approach to the use of logical units. Currently, the function information model represents only an external interface. This interface makes it possible to obtain, from the midst of algorithmic support, the values of necessary signals with the required semantics, which is functionally useful only for the SCADA. Thus, it turns out that the functional requirements for an LU should define the requirements for the external interface instead of the algorithmic support implementing the PAC function, which to a certain degree makes a nonsense. The article proposes to set up, for each LU, an independent separate algorithmic support, so that the algorithmic support structure would be consistent with that of the information model. In view of this feature, logical devices and units are developed that reflect the PAC functions for facilities of medium and high voltage classes. In addition, data objects are classified into input, output signals and setting parameters, and the extensions of LU information models, should a need to do so arises, are suggested. The study has revealed multiple applications of similar LUs in different PAC functions, which pose specific requirements for the LU operation. In this connection, it is decided to standardize the entire specific functional within a single LU type with the possibility to choose the necessary operation mode by changing the setting parameters. The development of the algorithmic support has revealed repeating types of LU algorithmic support structure, which were combined into three categories: measuring, starting-functional, and functional. For each of the LU types, there is a certain set of LU functional blocks. The designing of PAC functions on the basis of the new approach to the use of LUs has the following advantages: the protection scheme modular structure makes it possible to select the set of protection functions in a wide range at the designing stage; strict definition of interconnections and data exchange between LUs simplifies the understanding of protection operation, and opens the possibility to evaluate the influence of the LU operation mode on the performance of the protection function as a whole; the protection scheme modular structure with a predictable behavior of LUs makes it possible not only to monitor the correct operation of protection using special automatic tools, but also to automatically develop protection schemes. The disadvantage of this approach is the need to develop the PAC algorithmic support from scratch, because the previously developed algorithms do not imply the information model structure. The process of developing a logical device is shown within the article framework on the example of the medium voltage class overhead power line overcurrent protection with a detailed description of the logic device structure and the purpose of the presented LUs. A configurator software was developed during the study, which makes it possible to configure logical devices based on the library of developed LUs with subsequently making binary files to be uploaded on a hardware platform. The unambiguous description of information exchange between LUs generated the need to extend the SCL syntax, as a result of which a new format of CLD files was produced. The mechanism of applying reference data objects like InRef and BlkRef, that are part of the standard SCL syntax is not applicable because they lack semantic meaning. The article describes a successful process of testing and validation of the developed algorithms/logic units and logic devices on a hardware platform, as well as the problems revealed during the testing, which are connected with the lack of regulatory requirements for functional testing of logic units and methods for taking into account the impact of various quality labels of data objects.

This paper presents an optimal tuning of a proportional integral differential (PID) controller used to maintain glucose concentration at a desired set point. The PID controller synthesizes an appropriate feed rate profile for an E. coli fed-batch cultivation process. Mathematical models are developed based on dynamic mass balance equations for biomass, substrate, and product concentration of the E. coli BL21(DE3)pPhyt109 fed-batch cultivation for bacterial phytase extracellular production. For model parameter identification and PID tuning, a hybrid metaheuristic technique—chaotic electromagnetic field optimization (CEFO)—is proposed. In the hybridization, a chaotic map is used for the generation of a new electromagnetic particle instead of the electromagnetic field optimization (EFO) search strategy. The CEFO combines the exploitation capability of the EFO algorithm and the exploration power of ten different chaotic maps. The comparison of the results with classical EFO shows the superior behaviour of the designed CEFO. An improvement of 30% of the objective function is achieved by applying CEFO. Based on the obtained mathematical models, 10 PID controllers are tuned. The simulation experiments show that the designed controllers are robust, resulting in a good control system performance. The closed-loop transient responses for the corresponding controllers are similar to the estimated models. The settling time of the control system based on the third PID controller for all estimated models is approximately 9 min and the overshoot is approximately 15%. The proposed CEFO algorithm can be considered an effective methodology for mathematical modelling and achievement of high quality and better performance of the designed closed-loop system for cultivation processes.

In airline service the reliability of a system is more than the confirmed failures for the system; it is the total removal experience of the system. Thus, the reliability of a system lies not only in the piece part failure rates, but also in the capability to verify and isolate failures. The application of digital technology brings several significant reliability improvements to automatic flight control systems (AFCS) when compared to contemporary analog systems. These advantages are demonstrated by the experience of the digital air data computer (DADC) of the DC-10 and the digital AFCS of the JA-37 Viggen. Experience with this equipment is reviewed, and the results are interpreted in terms of projections for airline DAFCS reliability. The digital system built-in test implemented by a stored program and the central processor gives a system integrity and dispatch reliability unequaled by analog systems. This high-integrity self-test reduces removal rates by giving line personnel a trustworthy tool and more complete automatic test processes for verifying maintenance actions. Digital circuit technology is directly suitable to largescale integrated circuits (LSIC) which reduce piece part counts and improve LRU reliability. Digital circuits are less subject to drift and the attendant difficulty to detect failures. These factors, coupled with the inherent high-integrity self-test, provide the basis for a significant improvement in reliability by the use of a digital automatic flight control system.

Objective To design the control system of a magnetic resonance image (MRI) navigated pneumatic surgical robot. Method The driven system of the robot was constructed by combining with pneumatically driven and ultrasonic motor. The cylinder position control loop was established based on proportion integration differentiation (PID) control. The mathematical model of the pneumatic servo system was established by system identification. The PID parameter tuning and the simulation of the system characteristics were conducted. The stability analysis was conducted using the Nyquist criterion, and the acupuncture accuracy and the magnetic compatibility of the robot were verified. Results The simulation results showed that the maximum steady-state error was about 0.4 mm and the maximum tracking error was less than 2 mm, indicating that the PID control system had high control precision and trajectory tracking ability. The error of the acupuncture accuracy test was 0.72 mm. The results of water-modeling experiments showed that the magnetic resonance images were clear indicating that the influence of the robot on the MRI images was small. Conclusions The results of imulation, acupuncture and water-modeling tests showed that the pneumatic robot system can meet the requirements of brachytherapy surgery. Key words: Magnetic resonance imaging; Surgical robot; Pneumatic control system; PID control

This paper investigates the fuzzy Proportion Integration Differentiation (PID) controller for uncertain networked control systems (UNCSs). By combining T-S fuzzy model with the fuzzy PID controller, the uncertain networked control systems under transmission delays and external disturbances are proposed in this letter. Moreover, the asymptotically stability condition about the uncertain networked control systems is presented in the form of Lyapunov function and linear matrix inequality. The applicability of the proposed PID controller gain for uncertain networked control system is numerically tasted for various system parameters.

The recent development of drones has aroused great concern at home and abroad. For civil industry and agricultural plant protection industry, it can provide safer and more stable flight and improve production efficiency. For the exploration industry, the application of UAV (Unmanned Aerial Vehicle) will reduce unnecessary casualties. In places where damage is serious, UAV will bring accurate on-site information and data more quickly. It can make drones to replace people in high-risk operations, scientific and technological agricultural development and survey more stable and safe; For the military industry, it can be applied to different combat environments to increase its stability. In recent years, although UAV combat and reconnaissance are not the mainstream combat methods, UAV has become or an indispensable part. Improving the stability of UAV will also increase the military combat capability, so UAV has good development prospects and economic benefits. Nowadays, PID (Proportion Integration Differentiation) control plays an indispensable role in quad-rotor UAV. How to use different types of PID control combined with existing intelligent technology to improve the stability of quad-rotor UAV is a hot issue in recent years. This paper summarizes the previous research results in this field, briefly describes the motion mechanism of four-rotor UAV, wind disturbance resistance mechanism, the action principle and contract between traditional PID control and fuzzy PID control, as well as the effect of intelligent algorithm on PID control addition, and puts forward suggestions for PID control algorithm of the future UAV.

X-ray device used in the diagnosis has made possible to have more effective and accurate diagnosis, powered by the development of various devices. Based on this, X-ray device has become the most basic and essential diagnostic equipment in clinical medicine. At present, in the image acquisition field using X-ray, the use of Digital radiography which is useful in the acquisition time reduction and transfer of images and is possible to have the dose reduction has expanded. With the structure using one detector, this DR device has disadvantages in that it needs structural changes unlike existing X-ray and the detector should be moved to the desired position depending on the shooting location. Therefore, in this study, using BLDC(Brushless direct current) motor and PID(Proportional integral differential) control method, the automatic control system of 3-axis which is upward and downward, left and right and rotation of detector where having the most movement in DR was designed and produced and its performance was evaluated.

The thickness of the steel strip is an important indicator of the overall strip quality. Deviations in thickness are primarily controlled using the automatic gauge control (AGC) system of each rolling stand. At the last stand, the monitoring AGC system is usually used, where the deviations in thickness can be directly measured by the X-ray thickness gauge device and used as the input to the AGC system. However, due to the physical distance between the thickness detection device and the rolling stand, time delay is unavoidably present in the thickness control loop, which can affect control performance and lead to system oscillations. Furthermore, the parameters of the system can change due to perturbations from external disturbances. Therefore, this paper proposes an identification and control scheme for monitoring AGC system that can handle time delay and parameter uncertainty. The cross-correlation function is used to estimate the time delay of the system, while the system parameters are identified using a recursive least squares method. The time delay and parameter estimates are then further refined using the Levenberg-Marquardt algorithm, so as to provide the most accurate parameter estimates for the complete system. Simulation results show that, compared with the standard Proportion Integration Differentiation (PID) controller approach, the proposed approach is not affected by changes in the time delay and parameter uncertainties.

Active queue management (AQM) can keep smaller queuing delay and higher throughput by purposefully dropping the packets at the intermediate routers. Comparing with RED algorithm, although the PID (proportional-integral-differential) controller for AQM improves the stability. It is no systematic method in selecting a group of parameters for these controllers to guarantee the transient performance, and the case is much worse especially when the network parameters are time-varying. We use generalized predictive control to propose a predictive PID (PPID) controller for AQM router supporting TCP with slightly modified ECN to improve the robustness and transient performance of the PID controller. The simulation results show that the integrated performance of the controller is obviously superior to those of PID controller.

Fuzzy controller design of micro-unmanned helicopter relying on improved genetic optimization algorithm

The turret system is a precision mechanical system capable of carrying mission equipment to move in both azimuth and elevation degrees of freedom. The servo control of the turret usually adopts proportion-integration-differentiation (PID) control, However, when the turret perform target tracking or shooting tasks, it faces various impact responses such as vibration impact, center of mass change, elastic deformation, etc. The PID control method with fixed parameters cannot handle these unknown or unpredictable effects well. So, the combination of PID control and fuzzy reasoning decision is proposed to establish the dynamic fuzzy adaptive adjustment rules of PID parameters and build an adaptive fuzzy PID (FPID) controller to suppress external interference. The turret servo control models are given out first, then the fuzzy adjustment rules for PID parameters based on tracking error and error change rate are provided. Finally, to verify the superiority of the FPID algorithm over the PID algorithm, a comparative analysis was conducted on the target single maneuver with and without considering external influences. The simulation results show that the FPID can suppress external interference and FPID has higher accuracy than PID, especially in the case of target maneuvering and external response, its tracking error can be reduced by about 80%. This method can be used for the servo control of the turret system to improve the servo accuracy of the turret during the target tracking process.

Based on a high speed electromagnetism valve and a two side throttle slide valve, a digital shift pressure regulation valve was designed. The electromagnetism valve was driven directly by the digital signal of electricity control system, the automatic shifting and the pressure’s real time regulation of shift clutch was achieved. The principle of the electricity control system was stated, based on the characteristic of the electromagnetism valve, the drive circuit was designed. The digital electro hydraulic automatic control system was installed on the heavy vehicle with hydro mechanical transmission, and tested. According to the test data of shift process, the control strategy is analyzed, and the validity and feasibility of the control system is proved.