Control of out of balance servo mechanism subjected to external disturbances

There is a category of applications where cantilevered servomechanisms mounted on mobile platforms have to maintain very precise position in inertial space. These systems often referred to as stabilised or line of sight systems have to maintain precise orientation in inertial space in presence of linear and angular external disturbances. Stabilised systems, in general, are designed as balanced systems such that the pivot or centre of rotation coincides with the centre of gravity of the equipment. The research presented in this thesis investigates a general case of stabilising an out-of-balance mechanism; a balanced mechanism is a special case of these systems. The motivation for the research is to remove the requirement for balanced mechanisms enabling engineers to design more effective systems, both in terms of performance and costs, for future needs... cont'd

Development of FPGA-based Controllers for a Laboratory Model of a Spherical Inertial Reference Sensor with Optical Readout

Field Programmable Gate Arrays (FPGAs) are powerful and flexible instruments, particularly suited for the implementation of servo loops for experimental setups since they allow to frequently change the system without hardware modifications, thus resulting in a time and cost effective solution. Two FPGA-based controllers are presented in this thesis, developed in the frame of the construction of a laboratory model to investigate a novel inertial sensor concept for laser ranging space missions. The specific context of this work is the study of an alternative opto-mechanical architecture for the eLISA mission payload, for which an inertial reference sensor with a spherical test mass and optical readout has been proposed. Thanks to the possibility to operate the system in a full drag-free mode offered by the geometry of the test mass and to the high accuracy of the interferometric measurement of its center of mass, an advantage in terms of noise sensitivity of the sensor should be achieved with respect to the current baseline design. To validate this concept, a proof of its feasibility and an assessment of its performance need to be obtained with an earthbound laboratory model, whose success also relies, among other things, on the possibility to have stable laser signals for interferometric detection and a free-flying test mass kept in a steady position by a levitation system. Both these targets can be achieved through the implementation of an active control system stabilizing laser intensity via acousto-optic modulation in one case, and test mass height by means of a current modulated magnetic field in the other. The used servo loops, based on PID control scheme and implemented on a National Instruments FPGA board, are here described, focusing on the experimental characterization of the sensing and actuation hardware and on the controllers’ design through LabVIEW programming. Finally, the experimental trials carried out are illustrated, presenting the achieved results in terms of laser RIN reduction, the issues encountered for the test mass levitation and possible strategies for overcoming them in the continuation of the project

International Symposium on Magnetic Suspension Technology, Part 1

The goal of the symposium was to examine the state of technology of all areas of magnetic suspension and to review related recent developments in sensors and controls approaches, superconducting magnet technology, and design/implementation practices. The symposium included 17 technical sessions in which 55 papers were presented. The technical session covered the areas of bearings, sensors and controls, microgravity and vibration isolation, superconductivity, manufacturing applications, wind tunnel magnetic suspension systems, magnetically levitated trains (MAGLEV), space applications, and large gap magnetic suspension systems

Design and Development of a Next Generation Energy Storage Flywheel

Energy storage is crucial for both smart grids and renewable energy sources such as wind or solar, which are intermittent in nature. Compared to electrochemical batteries, flywheel energy storage systems (FESSs) offer many unique benefits such as low environmental impact, high power quality, and larger life cycles. This dissertation presents the design and development of a novel utility-scale FESS that features a shaftless, hubless rotor. The unique shaftless design gives it the potential of a doubled energy density and a compact form factor. Its energy and power capacities are 100 kWh and 100 kW, respectively. The flywheel is made of high-strength steel, which makes it much easier to manufacture, assemble, and recycle. Steels also cost much less than composite materials. In addition, the system incorporates a new combination active magnetic bearing. Its working principle and the levitation control for the flywheel are presented. The development of an integrated, coreless, permanent-magnet (PM) motor/generator for the flywheel is briefly discussed as well. Initial test results show that the magnetic bearing provides stable levitation for the 5443-kg flywheel with small current consumptions. Furthermore, this dissertation formulates and synthesizes a detailed model for designing and simulating a closed-loop control system for the proposed flywheel system at high speed. To this end, the magnetic bearing supporting structure is considered flexible and modeled by finite element modeling. The magnetic bearing is characterized experimentally by static and frequency-dependent coefficients, the latter of which are caused by eddy current effects and presents challenges to the levitation control. Sensor- runout disturbances are measured and included in the model. System nonlinearities in power amplifiers and the controller are considered as well. Even though the flywheel has a large ratio of the primary-to-transversal moment of inertias, Multi-Input-Multi-Output (MIMO) feedback control demonstrates its effectiveness in canceling gyroscopic torques and stabilize the system. Various stages of PD controllers, lead/lag compensators, and notch filters are also implemented to suppress the high-frequency sensor disturbances and structural vibrations

Steady-state, self-oscillating and chaotic behavior of a PID controlled nonlinear servomechanism by using Bogdanov-Takens and Andronov-Poincaré-Hopf bifurcations

This paper analyzes a controlled servomechanism with feedback and a cubic nonlinearity by means of the Bogdanov-Takens and Andronov-Poincaré-Hopf bifurcations, from which steady-state, self-oscillating and chaotic behaviors will be investigated using the center manifold theorem. The system controller is formed by a Proportional plus Integral plus Derivative action (PID) that allows to stabilize and drive to a prescribed set point a body connected to the shaft of a DC motor. The Bogdanov-Takens bifurcation is analyzed through the second Lyapunov stability method and the harmonic-balance method, whereas the first Lyapunov value is used for the Andronov-Poincaré-Hopf bifurcation. On the basis of the results deduced from the bifurcation analysis, we show a procedure to select the parameters of the PID controller so that an arbitrary steady-state position of the servomechanism can be reached even in presence of noise. We also show how chaotic behavior can be obtained by applying a harmonical external torque to the device in self-oscillating regime. The advantage of achieving chaotic behavior is that it can be used so that the system reaches a set point inside a strange attractor with a small control effort. The analytical calculations have been verified through detailed numerical simulations

Testing of MEMS gyroscopes

Tato diplomová práce se zabývá teoretickými poznatky o konstrukcích a parametrech MEMS gyroskopů. Dále je prezentován navržený měřicí řetězec pro testování MEMS gyroskopů ve společnosti Honeywell International s.r.o. a to zejména s použitím systémů: Polytec MSA-500, goniometrických plošin a kontroléru od firmy Standa a kontroléru pro řízení Peltierových článků. Praktická část diplomové práce obsahuje popis navrženého kontroléru pro řízení teploty testovaného zařízení a také popis aplikace v prostředí LabVIEW („Measurement systém“), která se používá pro řízení pozice dvou goniometrických plošin a pro řízení Peltierových článků. Tento systém je schopen plně řídit pozici goniometrických plošin, zarovnat povrch testovaného zařízení do ideálně kolmé pozice vůči optické hlavě analyzátoru Polytec MSA-500 a také kontrolovat teplotu testovaného zařízení. Závěrečná část diplomové práce je věnována testům základních parametrů MEMS gyroskopů se zaměřením na závislost tzv. Angle Random Walk a offsetu MEMS gyroskopu na kvalitě vakua v prostředí struktury.This diploma thesis presents theoretical information regarding MEMS gyroscopes their parameters and designs. The description of measurement chain be used for testing of MEMS gyroscopes in Honeywell International s.r.o. is presented. Special focus is devoted to: the Polytec MSA-500 system, the Standa goniometers and their controller, Peltier cell and its driver. The practical part of this thesis contains the description of the thermal control system and also the description of the developed “Measurement system” in the LabVIEW software which is used for controlling the goniometers position and the Peltier cell. The system is able to fully control two goniometer stages, align the surface of tested MEMS device to orthogonal position with respect to the Polytec MSA-500 measurement head and also control the temperature of the tested device. The last part of this thesis presents the tests of the MEMS gyroscope parameters with special focus to the MEMS gyroscope angle random walk and the bias dependence on the vacuum quality of the structure environment.

Robust Control

The need to be tolerant to changes in the control systems or in the operational environment of systems subject to unknown disturbances has generated new control methods that are able to deal with the non-parametrized disturbances of systems, without adapting itself to the system uncertainty but rather providing stability in the presence of errors bound in a model. With this approach in mind and with the intention to exemplify robust control applications, this book includes selected chapters that describe models of H-infinity loop, robust stability and uncertainty, among others. Each robust control method and model discussed in this book is illustrated by a relevant example that serves as an overview of the theoretical and practical method in robust control

NASA Tech Briefs, December 2006

Topic include: Inferring Gear Damage from Oil-Debris and Vibration Data; Forecasting of Storm-Surge Floods Using ADCIRC and Optimized DEMs; User Interactive Software for Analysis of Human Physiological Data; Representation of Serendipitous Scientific Data; Automatic Locking of Laser Frequency to an Absorption Peak; Self-Passivating Lithium/Solid Electrolyte/Iodine Cells; Four-Quadrant Analog Multipliers Using G4-FETs; Noise Source for Calibrating a Microwave Polarimeter; Hybrid Deployable Foam Antennas and Reflectors; Coating MCPs with AlN and GaN; Domed, 40-cm-Diameter Ion Optics for an Ion Thruster; Gesture-Controlled Interfaces for Self-Service Machines; Dynamically Alterable Arrays of Polymorphic Data Types; Identifying Trends in Deep Space Network Monitor Data; Predicting Lifetime of a Thermomechanically Loaded Component; Partial Automation of Requirements Tracing; Automated Synthesis of Architecture of Avionic Systems; SSRL Emergency Response Shore Tool; Wholly Aromatic Ether-Imides as n-Type Semiconductors; Carbon-Nanotube-Carpet Heat-Transfer Pads; Pulse-Flow Microencapsulation System; Automated Low-Gravitation Facility Would Make Optical Fibers; Alignment Cube with One Diffractive Face; Graphite Composite Booms with Integral Hinges; Tool for Sampling Permafrost on a Remote Planet; and Special Semaphore Scheme for UHF Spacecraft Communications

Study of an attitude reference system utilizing an electrically suspended gyro final report, 1 aug. 1964 - 31 mar. 1965

Miniature electrically suspended gyroscope for spacecraft attitude reference syste

Automatic Flight Control Systems

The history of flight control is inseparably linked to the history of aviation itself. Since the early days, the concept of automatic flight control systems has evolved from mechanical control systems to highly advanced automatic fly-by-wire flight control systems which can be found nowadays in military jets and civil airliners. Even today, many research efforts are made for the further development of these flight control systems in various aspects. Recent new developments in this field focus on a wealth of different aspects. This book focuses on a selection of key research areas, such as inertial navigation, control of unmanned aircraft and helicopters, trajectory control of an unmanned space re-entry vehicle, aeroservoelastic control, adaptive flight control, and fault tolerant flight control. This book consists of two major sections. The first section focuses on a literature review and some recent theoretical developments in flight control systems. The second section discusses some concepts of adaptive and fault-tolerant flight control systems. Each technique discussed in this book is illustrated by a relevant example