Robust and Optimal PID Controller Synthesis for Linear Time Invariant Systems

We dealt with new approaches to the design of Proportional-Integral-Derivative (PID) controllers and solved three important open problems: 1) Optimal design of H∞ continuous time controllers 2) Optimal design of H∞ discrete time controllers and 3) Design of PID controllers for prescribed settling time. We also deal with optimal Dynamic Compensator design for controllable and observable systems. The main result of the first problem is a constructive determination of the set Sγ of stabilizing continuous PI and PID controllers achieving an H∞ norm bound of γ on the error transfer function. This result utilizes the computation of the complete stabilizing set S. We also point out connections between this H∞ design and Gain and Phase Margin designs. The main result of the second problem is a constructive characterization of the set Sγ of stabilizing digital controllers achieving a prescribed bound γ on the error transfer function. This is accomplished by utilizing the computation of S, the set of all PID stabilizing controllers. The minimum achievable γ, denoted γ∗ is also determined. The main result of the third problem is a constructive determination of the set S(σ) of stabilizing PI and PID controllers with closed loop poles having real parts less than −σ. The signature method is applied to obtain the set S(σ) in the controller parameter space. The maximum achievable σ for a given plant is also determined. The main result of the last problem is a new approach to design an optimal dynamic compensator. The system is augmented with a proper number of integrators and the state feedback of the augmented system is considered with a design parameter. The dynamic compensator is then designed such that the eigenvalues of the augmented system is identical to the closed loop specboundtrum of the implemented system with the compensator. By sweeping over the design parameter, multiple design specifications are compared within achievable boundary of performances

Robust and Optimal PID Controller Synthesis for Linear Time Invariant Systems

We dealt with new approaches to the design of Proportional-Integral-Derivative (PID) controllers and solved three important open problems: 1) Optimal design of H∞ continuous time controllers 2) Optimal design of H∞ discrete time controllers and 3) Design of PID controllers for prescribed settling time. We also deal with optimal Dynamic Compensator design for controllable and observable systems. The main result of the first problem is a constructive determination of the set Sγ of stabilizing continuous PI and PID controllers achieving an H∞ norm bound of γ on the error transfer function. This result utilizes the computation of the complete stabilizing set S. We also point out connections between this H∞ design and Gain and Phase Margin designs. The main result of the second problem is a constructive characterization of the set Sγ of stabilizing digital controllers achieving a prescribed bound γ on the error transfer function. This is accomplished by utilizing the computation of S, the set of all PID stabilizing controllers. The minimum achievable γ, denoted γ∗ is also determined. The main result of the third problem is a constructive determination of the set S(σ) of stabilizing PI and PID controllers with closed loop poles having real parts less than −σ. The signature method is applied to obtain the set S(σ) in the controller parameter space. The maximum achievable σ for a given plant is also determined. The main result of the last problem is a new approach to design an optimal dynamic compensator. The system is augmented with a proper number of integrators and the state feedback of the augmented system is considered with a design parameter. The dynamic compensator is then designed such that the eigenvalues of the augmented system is identical to the closed loop specboundtrum of the implemented system with the compensator. By sweeping over the design parameter, multiple design specifications are compared within achievable boundary of performances

CLOCK SYNCHRONIZATION AND TARGET LOCATION DETERMINATION IN WIRELESS NETWORKS

In a distributed system most nodes maintain a local oscillator to derive time information for synchronization with other nodes. A number of clock synchronization techniques have been presented in the literature (e.g. NTP, PTP) which rely on the exchange of messages among nodes to share timing information and to adjust the oset or skew of the clocks. We present an approach which does not require any adjustments to the local clocks, but relies on achieving synchronization through clock mapping functions which map the time at one node to the time at another node. We further show how closed paths in a graph of nodes can be used to estimate the synchronization tolerance. Through experimental results using piecewise linear functions, we demonstrate the feasibility of this approach and show how clock synchronization of better than 100 ps can be achieved in Wi-Fi environments. Using the techniques and relying on the hardware of SMiLE3 board, we also demonstrate the ability to measure distance with accuracy of a few inches and thereby the localization to accuracy better than one foot. Results of experiments conducted for localization are also presented

System Design for Software Packet Processing

The role of software in computer networks has never been more crucial than today, with the advent of Internet-scale services and cloud computing. The trend toward software-based network dataplane—as in network function virtualization—requires software packet processing to meet challenging perfomance requirements, such as supporting exponentially increasing link bandwidth and microsecond-order latency. Many architectural aspects of existing software systems for packet processing, however, are decades old and ill-suited totoday’s network I/O workloads.In this dissertation, we explore the design space of high-performance software packet processing systems in the context of two application domains, . First, we start by discussingthe limitations of BSD Socket, which is a de-facto standard in network I/O for server applications. We quantify its performance limitations and propose a clean-slate API, called MegaPipe, as an alternative to BSD Socket. In the second part of this dissertation, we switch our focus to in-network software systems for network functions, such as network switches and middleboxes. We present Berkeley Extensible Software Switch (BESS), a modular framework for building extensible network functions. BESS introduces various novel techniques to achieve high-performance software packet processing, without compromising on either programmability or flexibility

Forecasting Crude Oil Prices with Major S&P 500 Stock Prices: Deep Learning, Gaussian Process, and Vine Copula

This paper introduces methodologies in forecasting oil prices (Brent and WTI) with multivariate time series of major S&P 500 stock prices using Gaussian process modeling, deep learning, and vine copula regression. We also apply Bayesian variable selection and nonlinear principal component analysis (NLPCA) for data dimension reduction. With a reduced number of important covariates, we also forecast oil prices (Brent and WTI) with multivariate time series of major S&P 500 stock prices using Gaussian process modeling, deep learning, and vine copula regression. To apply real data to the proposed methods, we select monthly log returns of 2 oil prices and 74 large-cap, major S&P 500 stock prices across the period of February 2001-October 2019. We conclude that vine copula regression with NLPCA is superior overall to other proposed methods in terms of the measures of prediction errors

Management of Road Infrastructure Safety

Road Infrastructure Safety Management (RISM) refers to a set of procedures that support a road authority in decision making related to the improvement of safety on a road network. Some of these procedures can be applied to existing infrastructure, thus enabling a reactive approach; and other procedures are used in early stages of a project's life-cycle allowing a proactive approach. The objective of this paper is to provide an overview of the most well-known procedures and present a series of recommendations for successful road infrastructure safety management. The work described in the paper was completed by the IRTAD sub-working group on Road Infrastructure Safety Management and presented in detail in the respective Report. The methodology followed on this purpose included the description of the most consolidated RISM procedures, the analysis of the use of RISM procedures worldwide and the identification of possible weaknesses and barriers to their implementation, the provision of good practice examples and the contribution to the scientific assessment of procedures. Specifically, the following RISM procedures were considered: Road Safety Impact Assessment (RIA), Efficiency Assessment Tools (EAT), Road Safety Audit (RSA), Network Operation (NO), Road Infrastructure Safety Performance Indicators (SPI), Network Safety Ranking (NSR), Road Assessment Programs (RAP), Road Safety Inspection (RSI), High Risk Sites (HRS) and In-depth Investigation. Each procedure was described along with tools and data needed for its implementation as well as relevant common practices worldwide. A synthesis summarizing the key information for each procedure was also drafted. Based on a survey on 23 IRTAD member countries from worldwide, the lack of resources or tools is the most commonly stated reason for not applying a RISM procedure. This has been frequently found mainly in European countries. Another common reason is the absence of recommendations/guidelines, especially for SPI, RAP, RSI and RSA. This highlights the importance of the presence of some legislation regulating the application of the procedures. Lack of data was found important mainly for SPI, HRS and EAT. Good practices of road infrastructure safety management have been explored in order to find solutions to the issues highlighted by the survey and provide examples about how these issues have been overcome in some countries. Specifically, issues related to data, legal framework, funding, knowledge, tools and dealing with more RISM procedures were addressed. Finally, nine key messages and six recommendations for better Road Infrastructure Safety Management were developed based on the conclusions made

E2: a framework for NFV applications

By moving network appliance functionality from proprietary hardware to software, Network Function Virtualization promises to bring the advantages of cloud computing to network packet processing. However, the evolution of cloud computing (particularly for data analytics) has greatly bene- fited from application-independent methods for scaling and placement that achieve high efficiency while relieving programmers of these burdens. NFV has no such general management solutions. In this paper, we present a scalable and application-agnostic scheduling framework for packet processing, and compare its performance to current approaches

A Contact Force Sensor based on S-shaped Beams and Optoelectronic Sensors for Flexible Manipulators for Minimally Invasive Surgery (MIS)

Flexible, highly articulated robotic tools can greatly facilitate procedures in which the operator needs to access small openings and confined spaces. Particularly, in the context of robotic-assisted minimally invasive surgery (RMIS), the application of such manipulation tools can be significantly beneficial in preventing unnecessary interactions with sensitive body organs by which reducing patient’s recovery time when compared with conventional methods. However, these systems usually lack tactile feedback and are not able to perceive and quantify the interactions between themselves and soft body organs. This deficiency may result in damaging the organs due to unwanted excessive force applied. To this end, we introduce a contact force sensor based on three 'dyadic-S-shaped' beams and three optoelectronic sensors. The modular design of a flexible manipulation system described as part of this paper allows ready integration of a series of the proposed sensors within its structure. The sensor uses our novel sensing principle for measuring contact forces. The strategic employment of custom sensor structure and the optoelectronic components fulfill our design objectives which has been focused on the creation of a modular, low-cost, low-noise (electrically) with large voltage variation, without the need for an amplifier, through a simple fabrication process for MIS. Our experimental results, following a very simple calibration processes show the average errors of Fx (+19.37%±0.82, -18.32%±2.06) and Fy (+18.56%±1.69, -17.00%±1.32), and the average RMS errors of Fx (0.12N±0.0067) and Fy (0.11N±0.0032) in the measurement of force values within the range of -4 to 4 N