Purely Analog Fractional Order PI Control Using Discrete Fractional Capacitors (Fractors): Synthesis and Experiments

2009 ◽  
Author(s):  
Shayok Mukhopadhyay ◽  
Calvin Coopmans ◽  
YangQuan Chen
Keyword(s):  
Fractional Order ◽  
Digital Control ◽  
Circuit Board ◽  
Pi Control ◽  
Control Techniques ◽  
System A ◽  
Analog Control ◽  
Tank System ◽  
Digital Methods ◽  
Future Work

This paper presents the results of experiments related to analog fractional order PI control of a coupled tank system. A custom circuit board has been built to perform analog PID/FOPID control. Specialized circuit elements called ‘Fractors’ [1] are used to perform fractional order integration/differentiation of the error signals. The design of the board, subsequent experimentation and its comparison to similar digital control techniques have been presented. The benefits of purely analog control when dealing with non-linearities are also discussed. Further, methods of approximating a particular fractional order α* with any number of practically available orders α1, α2, ....αn has also been presented. The conclusion of this work examines the need for purely analog control as opposed to widespread digital methods and also lays down definite directions for future work.

A comparative study of phase margin based digital and analog controlled synchronous buck with optimum LC filter

2019 ◽  
Vol 38 (6) ◽  
pp. 2020-2039
Author(s):  
Ruchi Rashmi ◽  
Shweta Jagtap
Keyword(s):  
Discrete Time ◽  
Digital Control ◽  
Buck Converter ◽  
Pi Control ◽  
Phase Margin ◽  
Control Loop ◽  
Digital Controllers ◽  
Pass Filter ◽  
Content Type ◽  
Analog Control

Purpose Traditionally, industrial power supplies have been exclusively controlled through analog control to sustain high reliability with low cost. However, with the perpetual decrement in cost of digital controllers, the feasibility of a digitally controlled switch mode power supply has elevated significantly. This paper aims to outline the challenges related to the design of digital proportional-integral (PI) controlled synchronous rectifier (SR) buck converter by comparing controller performance in continuous and discrete time. The trapezoidal approximation-based digital PI control is designed for low voltage and high-frequency SR buck converter operating under continuous conduction mode. Design/methodology/approach The analog and digital controller are designed using a SISO tool of MATLAB. Here, zero-order hold transform is used to convert the transfer function from continuous to discrete time. Frequency and time domain analysis of continuous plant, discrete plant and close loop system is performed. The designed digital PI control is simulated in MATLAB Simulink. The simulated results is also verified on hardware designed around digital signal processing control. Findings The continuous and discrete control loops are validated with multiple tests in the time and frequency domain. The detailed steady state theoretical analysis and performance of the SR buck converter is presented and verified by simulation. It is found that the delay in digital control loop results in a low phase margin. This phase margin decreases with higher bandwidth. The hardware experiments with the digital control loop are carried out on a 10 W prototype. The chosen parameters for the SR buck converter are found to be optimum for steady and transient state response. Originality/value This paper compares the digital and analog control approach of compensator design. It focuses on the implications created at the time of transforming the control design from continuous to discrete time. Further, it also focuses on the selection of parameters such as phase margin, bandwidth and low pass filter.

Brain angiotensin system: a new promise in the management of epilepsy?

2021 ◽  
Vol 135 (6) ◽  
pp. 725-730
Author(s):  
Alberto Javier Ramos
Keyword(s):  
Therapeutic Potential ◽  
Renin Angiotensin System ◽  
B Cell Lymphoma ◽  
Ang Ii ◽  
Angiotensin System ◽  
Beneficial Effects ◽  
System A ◽  
Pilocarpine Model ◽  
Animal Models Of Epilepsy ◽  
Future Work

Abstract Epilepsy is a highly prevalent neurological disease and anti-epileptic drugs (AED) are almost the unique clinical treatment option. A disbalanced brain renin–angiotensin system (RAS) has been proposed in epilepsy and several reports have shown that angiotensin II (Ang II) receptor-1 (ATR1) activation is pro-inflammatory and pro-epileptogenic. In agreement, ATR1 blockage with the repurposed drug losartan has shown benefits in animal models of epilepsy. Processing of Ang II by ACE2 enzyme renders Ang-(1-7), a metabolite that activates the mitochondrial assembly (Mas) receptor (MasR) pathway. MasR activation presents beneficial effects, facilitating vasodilatation, increasing anti-inflammatory and antioxidative responses. In a recent paper published in Clinical Science, Gomes and colleagues (Clin. Sci. (Lond.) (2020) 134, 2263–2277) performed intracerebroventricular (icv) infusion of Ang-(1-7) in animals subjected to the pilocarpine model of epilepsy, starting after the first spontaneous motor seizure (SMS). They showed that this approach reduced the frequency of SMS, restored animal anxiety, increased exploration, and augmented the hippocampal expression of protective catalase enzyme and antiapoptotic protein B-cell lymphoma 2 (Bcl-2). Interestingly, but surprisingly, Gomes and colleagues showed that MasR expression and mTor activity were reduced in the hippocampus of the epileptic Ang-(1-7) treated animals. These results show that Ang-(1-7) administration could represent a new avenue for developing strategies for the management of epilepsy in clinical settings. However, future work is necessary to evaluate the levels of RAS metabolites and the activity of key enzymes in these experimental interventions to completely understand the therapeutic potential of the brain RAS manipulation in epilepsy.

Robotic system design and development for automated dismantling of PCB waste

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ioan Doroftei ◽  
Daniel Chirita ◽  
Ciprian Stamate ◽  
Stelian Cazan ◽  
Carlos Pascal ◽  
...  
Keyword(s):  
Design Methodology ◽  
Printed Circuit Board ◽  
Vision System ◽  
Electronic Waste ◽  
Robotic System ◽  
Circuit Board ◽  
Short Introduction ◽  
Content Type ◽  
Printed Circuit ◽  
System A

Purpose The mass electronics sector is one of the most critical sources of waste, in terms of volume and content with dangerous effects on the environment. The purpose of this study is to provide an automated and accurate dismantling system that can improve the outcome of recycling. Design/methodology/approach Following a short introduction, the paper details the implementation layout and highlights the advantages of using a custom architecture for the automated dismantling of printed circuit board waste. Findings Currently, the amount of electronic waste is impressive while manual dismantling is a very common and non-efficient approach. Designing an automatic procedure that can be replicated, is one of the tasks for efficient electronic waste recovery. This paper proposes an automated dismantling system for the advanced recovery of particular waste materials from computer and telecommunications equipment. The automated dismantling architecture is built using a robotic system, a custom device and an eye-to-hand configuration for a stereo vision system. Originality/value The proposed approach is innovative because of its custom device design. The custom device is built using a programmable screwdriver combined with an innovative rotary dismantling tool. The dismantling torque can be tuned empirically.

scholarly journals Digital methods for measuring grain size parameters of aggregate–binder mixtures.

2013 ◽  
Vol 47 (4) ◽  
pp. 1834
Author(s):  
E. Profitis ◽  
D. Kapatos ◽  
E. Chatzitheodoridis ◽  
D. Xirouchakis ◽  
C. Loupasakis
Keyword(s):  
Three Dimensional ◽  
Two Dimensions ◽  
Geometrical Parameters ◽  
Bituminous Mixtures ◽  
Dimensional Measurements ◽  
Digital Methods ◽  
Significant Cost Reduction ◽  
Future Work ◽  
Grain Size Parameters ◽  
Exact Separation

Geometrical parameters of natural and crushed aggregates such as grain length, perimeter, area, etc., underline the shape and flakiness indices definition. The latter indices have a measurable effect on the mechanical properties of aggregates–binder mixtures, e.g. concrete, mortar, bituminous mixtures. In this work, digital methods were developed with the mathematical software Matlab, by applying a statistical method called k-means clustering for the exact separation between background and aggregates to compute the aforementioned properties. The overall code can be applied in real time by analysing quickly a large volume of data with accuracy and significant cost reduction. Currently, only the two dimensions of the grains could be measured. Future work will focus on full three-dimensional measurements by comparing paired images taken from different angles but also aggregate segmentation in case of touching particles.

scholarly journals Mathematical modelling of the mass-spring-damper system - A fractional calculus approach

2012 ◽  
Vol 22 (5) ◽  
pp. 5-11 ◽  
Author(s):  
José Francisco Gómez Aguilar ◽  
Juan Rosales García ◽  
Jesus Bernal Alvarado ◽  
Manuel Guía
Keyword(s):  
Differential Equation ◽  
Fractional Calculus ◽  
Mathematical Modelling ◽  
Fractional Differential Equation ◽  
Fractional Order ◽  
Time Derivative ◽  
System A ◽  
Fractional Differential ◽  
Mass Spring ◽  
Derivatives Of

In this paper the fractional differential equation for the mass-spring-damper system in terms of the fractional time derivatives of the Caputo type is considered. In order to be consistent with the physical equation, a new parameter is introduced. This parameter char­acterizes the existence of fractional components in the system. A relation between the fractional order time derivative and the new parameter is found. Different particular cases are analyzed

Application of Digital Control Techniques for Satellite Medium Power DC-DC Converters

2011 ◽  
Vol 57 (1) ◽  
pp. 77-83 ◽  
Author(s):  
Konrad Skup ◽  
Paweł Grudziński ◽  
Piotr Orleański
Keyword(s):  
Digital Control ◽  
High Speed ◽  
Control Process ◽  
Digital Signal ◽  
Current Mode ◽  
Power Converter ◽  
Buck Converter ◽  
Research Centre ◽  
Analog To Digital ◽  
Control Techniques

Application of Digital Control Techniques for Satellite Medium Power DC-DC Converters The objective of this paper is to present a work concerning a digital control loop system for satellite medium power DC-DC converters that is done in Space Research Centre. The whole control process of a described power converter is based on a high speed digital signal processing. The paper presents a development of a FPGA digital controller for voltage and current mode stabilization that was implemented using VHDL. The described controllers are based on a classical digital PID controller. The converter used for testing is a 200 kHz, 750W buck converter with 50V/15A output. A high resolution digital PWM approach is presented. Additionally a simple and effective solution of filtering of an analog-to-digital converter output is presented.

An active control for hydrostatic journal bearing using optimization algorithms

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Waheed Ur Rehman ◽  
Xinhua Wang ◽  
Yingchun Chen ◽  
Xiaogao Yang ◽  
Zia Ullah ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Peer Review ◽  
Fractional Order ◽  
Journal Bearing ◽  
Optimization Techniques ◽  
Performance Criteria ◽  
Content Type ◽  
Control Techniques ◽  
Fractional Order Controller ◽  
Fractional Order Pid

Purpose The purpose of this paper is to improve static/dynamic characteristics of active-controlled hydrostatic journal bearing by using fractional order control techniques and optimizing algorithms. Design/methodology/approach Active lubrication has ability to overcome the unpredictable harsh environmental conditions which often lead to failure of capillary controlled traditional hydrostatic journal bearing. The research develops a mathematical model for a servo feedback-controlled hydrostatic journal bearing and dynamics of model is analyzed with different control techniques. The fractional-order PID control system is tuned by using particle swarm optimization and Nelder mead optimization techniques with the help of using multi-objective performance criteria. Findings The results of the current research are compared with previously published theoretical and experimental results. The proposed servo-controlled active bearing system is studied under a number of different dynamic situations and constraints of variable spindle speed, external load, temperature changes (viscosity) and variable bearing clearance (oil film thickness). The simulation results show that the proposed system has better performance in terms of controllability, faster response, stability, high stiffness and strong resistance. Originality/value This paper develops an accurate mathematical model for servo-controlled hydrostatic bearing with fractional order controller. The results are in excellent agreement with previously published literature. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0272

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