Constructive interconnection and damping assignment passivity-based control with applications

Energy-based modeling and control of dynamical systems is crucial since energy is a fundamental concept in Science and Engineering theory and practice. While Interconnection and Damping Assignment Passivity-based Control (IDA-PBC) is a powerful theoretical tool to control port-controlled Hamiltonian (PCH) systems that arise from energy balancing principles, sensorless operation of energy harvesters is a promising practical solution for low-power energy generation. The thesis addresses these two problems of energy-based control and efficient energy generation. The design via IDA-PBC hinges on the solution of the so-called matching equation which is the stumbling block in making this method widely applicable. In the first part of the thesis, a constructive approach for IDA-PBC for PCH systems that circumvents the solution of the matching equation is presented. A new notion of solution for the matching equation, called algebraic solution, is introduced. This notion is instrumental for the construction of an energy function defined on an extended state-space. This yields, differently from the classical solution, a dynamic state-feedback that stabilizes a desired equilibrium point. In addition, conditions that preserve the PCH structure in the extended closed-loop system have been provided. The theory is validated on four examples: a two-dimensional nonlinear system, a magnetic levitated ball, an electrostatic microactuator and a third order food-chain system. For these systems damping structures that cannot be imposed with the standard approach are assigned. In the second part of the thesis, the design of a nonlinear observer and of an energy-based controller for sensorless operation of a rotational energy harvester is presented. A mathematical model of the harvester with its power electronic interface is developed. This model is used to design an observer that estimates the mechanical quantities from the measured electrical quantities. The gains of the observer depend on the solution of a modified Riccati equation. The estimated mechanical quantities are used in a feedback control law that sustains energy generation across a range of source rotation speeds. The proposed observer-controller scheme is assessed through simulations and experiments.Open Acces

Positioning Control System for a Large Range 2D Platform with Submicrometre Accuracy for Metrological and Manufacturing Applications

The importance of nanotechnology in the world of Science and Technology has rapidly increased over recent decades, demanding positioning systems capable of providing accurate positioning in large working ranges. In this line of research, a nanopositioning platform, the NanoPla, has been developed at the University of Zaragoza. The NanoPla has a large working range of 50 mm × 50 mm and submicrometre accuracy. The NanoPla actuators are four Halbach linear motors and it implements planar motion. In addition, a 2D plane mirror laser interferometer system works as positioning sensor. One of the targets of the NanoPla is to implement commercial devices when possible. Therefore, a commercial control hardware designed for generic three phase motors has been selected to control and drive the Halbach linear motors.This thesis develops 2D positioning control strategy for large range accurate positioning systems and implements it in the NanoPla. The developed control system coordinates the performance of the four Halbach linear motors and integrates the 2D laser system positioning feedback. In order to improve the positioning accuracy, a self calibration procedure for the characterisation of the geometrical errors of the 2D laser system is proposed. The contributors to the final NanoPla positioning errors are analysed and the final positioning uncertainty (k=2) of the 2D control system is calculated to be ±0.5 µm. The resultant uncertainty is much lower than the NanoPla required positioning accuracy, broadening its applicability scope.<br /

Applying API 617, 8th Edition to Expander-Compressors with Active Magnetic Bearings

TutorialHigh-speed expander-compressors are commonplace in the gasprocessing industry. In recent years, expander-compressors equipped with Active Magnetic Bearings (AMBs) have gained wide acceptance and are now the norm in ethylene plant refrigeration turboexpander applications and increasingly specified for gas-liquid separation. Further improvements in magnetic bearings are simplifying the technology for those responsible to purchase, commission and maintain rotating machines. As well, it is becoming easier to verify that AMB machines comply with accepted design standards. The Eighth Edition of API617, released in September 2014, includes a new annex (Part 1, Annex E) and other material, specifically addressing AMB-equipped machinery. Unlike previous editions which included only informative material, this new material provides a detailed criteria by which AMB designers, purchasers and users can evaluate API compliance or AMB-equipped machines. These design, analysis and test specifications reduce the technical complexity of AMB technology for expander-compressor stakeholders, and contribute to continued growth in the market place. This tutorial will discuss and demonstrate the application of API617, 8th Edition to AMB-equipped expander-compressors from a practical, user-oriented point of view

G2 Flywheel Module Design

Design of a flywheel module, designated the G2 module, is described. The G2 flywheel is a 60,000 RPM, 525 W-hr, 1 kW system designed for a laboratory environment; it will be used for component testing and system demonstrations, with the goal of applying flywheels to aerospace energy storage and integrated power and attitude control (IPACS) applications. G2 has a modular design, which allows for new motors, magnetic bearings, touchdown bearings, and rotors to be installed without a complete redesign of the system. This design process involves several engineering disciplines, and requirements are developed for the speed, energy storage, power level, and operating environment. The G2 rotor system consists of a multilayer carbon fiber rim with a titanium hub on which the other components mount, and rotordynamics analysis is conducted to ensure rigid and flexible rotor modes are controllable or outside of the operating speed range. Magnetic bearings are sized using 1-D magnetic circuit analysis and refined using 3-D finite element analysis. The G2 magnetic bearing system was designed by Texas A&M and has redundancy which allows derated operation after the loss of some components, and an existing liquid cooled two pole permanent magnet motor/generator is used. The touchdown bearing system is designed with a squeeze film damper system allowing spin down from full operating speed in case of a magnetic bearing failure. The G2 flywheel will enable module level demonstrations of component technology, and will be a key building block in system level attitude control and IPACS demonstrations

Estimation and control of the pump pressure rise and flow from intrinsic parameters for a magnetically-levitated axial blood pump

An increase in the number of cardiac patients and a decrease in number of heart donors has triggered the development of artificial heart pump to support the proper functioning of the heart. There is also an increase in demand for smaller sized pumps with long term application. All these factors have stimulated the use of a magnetically-levitated rotary blood pump as Left Ventricular Assistant Devices. The demand of volume and pressure of blood varies from person to person. Moreover, the prevention of cannular ventricle collapse at suction, dependence of pump performance on its inlet, and outlet conditions has necessitated control of the pump. Also, the available invasive pressure and flow transducers limit the use, due to their low reliability, periodic calibration, and assembling problem. In this work, three independent and quantitative non-invasive measurement methods for the estimation of pump parameters from intrinsic parameters were developed, substantiated, and compared. The first method used DC motor current and the motor speed as the inputs to the system. In this method, behavior of brushless DC motor was studied using its working model. Pump speed and bearing current were the inputs for the second estimation technique. In this method, pump performance and impeller behavior were continuously monitored in three axes (X,Y, ). The third method is conceptualized on the output of the Hall Effect sensors, which were used for sensing the position of impeller, and the pump speed. The behavior of the sensor output with the impeller position in four axes (X,Y,Z, ) was developed using a real impeller in model housing. The data were analyzed in Microsoft Excel 2007 and MATLAB using least square estimation techniques and Fourier series expansion. An algorithm for each technique was developed. In addition, the propagation of errors and uncertainties at each step of estimation method were accounted and calculated, with the results for each method compared