Development and applications of new sliding mode control approaches

Ph.DDOCTOR OF PHILOSOPH

Backstepping integral sliding mode control of an electromechanical system

The aim of this paper is to design a backstepping integral sliding mode controller (BISMC) for speed control of an electromechanical system under uncertainties and disturbances. An integral dynamic is included in traditional sliding surface to improve chattering and steadystate error in tracking a reference signal when parametric uncertainties and disturbances exist. Design and stability of the closed-loop system is realized by Lyapunov criterion in a step by step procedure. Experimental results of the proposed BISMC are compared with those of the traditional sliding mode controller (SMC). The proposed BISMC achieves reasonable tracking performance and exhibits more robust performance concerning parametric uncertainties and disturbances than the traditional SMC

Index to NASA Tech Briefs, 1974

The following information was given for 1974: (1) abstracts of reports dealing with new technology derived from the research and development activities of NASA or the U.S. Atomic Energy Commission, arranged by subjects: electronics/electrical, electronics/electrical systems, physical sciences, materials/chemistry, life sciences, mechanics, machines, equipment and tools, fabrication technology, and computer programs, (2) indexes for the above documents: subject, personal author, originating center

NASA Tech Briefs Index, 1977, volume 2, numbers 1-4

Announcements of new technology derived from the research and development activities of NASA are presented. Abstracts, and indexes for subject, personal author, originating center, and Tech Brief number are presented for 1977

Digital control systems in the regeneration cavity of ALPS IIa

ALPS II ist ein Licht durch die Wand-Experiment, das nach axionartigen Teilchen sucht. Diese Experimente zielen darauf ab axionartige Teilchen in einem Labor zu erzeugen und zu messen, wobei in Gegenwart eines Magnetfelds die Oszillation zwischen Photonen und axionartige Teilchen erfolgt. ALPS II baut auf die Neuerungen seines Vorgängerexperiments ALPS I auf: optische Resonatoren zur Verbesserung der Empfindlichkeit. ALPS II wird einen Produktionsresonator (PC) verwenden, um die Anzahl der zur Erzeugung von axionartigen Teilchen verfügbaren Photonen zu erhöhen und einen Regenerationsresonator (RC), um die Wahrscheinlichkeit zu erhöhen, dass axionartige Teilchen zurück in Photonen konvertieren. Um das Licht in den Resonatoren resonant zu überhöhen, muss das auf den Resonator einfallende Laserlicht, auch in Gegenwart von Rauschquellen, an die Resonanz des Resonators angepasst werden. Zusätzlich müssen die Resonanzen der beiden Resonatoren so aufeinander abgestimmt werden, dass die Rekonversionswahrscheinlichkeit der axionartigen Teilchen im RC erhöht wird. Die Anforderung an das Frequenzrauschen zwischen den beiden Resonatoren für ALPS IIc müssen kleiner sein als eine Effektivwertabweichung (RMS) von 3.0 Hz. Dies erfordert die Verwendung von Regelkreisen mit hohen Regelbandbreiten. ALPS IIa ist ein kleineres Experiment zum Testen und Charakterisieren kritischer Systeme für den Einsatz in ALPS IIc. ALPS IIa verfügt über Räumlichkeiten, in denen zwei Resonatoren, ähnlich der PC und RC in ALPS IIc, aufgebaut sind. Regelkreise können entworfen und getestet werden, um sie für die Eignung in ALPS IIc zu testen und die Leistungsfähigkeit alternativer Designs kann im kleinen Maßstab evaluiert werden. In dieser Dissertation werden die grundlegenden analogen Regelkreise der ALPS IIa RC charakterisiert. Dazu gehören Frequenzstabilisierungssysteme für zwei Laserquellen und ein Längenstabilisierungssystem. Das Rauschen dieses Längenstabilisierungssystems wird auf die Anforderungen der Resonanzüberlappung zwischen den beiden Resonatoren projiziert und ein RMS Wert von 1.0 Hz sollte mit diesem System erreicht werden. Um die Funktionsfähigkeit digitaler Regelsysteme zu untersuchen, werden zwei digitale Frequenzstabilisierungssysteme getestet: eines, das analoge Servo ersetzt, und eines, das zusätzlich das analoge Demodulationssystem ersetzt. Das RMS des Frequenzrauschens beider digitaler Systeme liegt innerhalb eines Faktors von zwei des vollständig analogen Systems. Das System mit der digitalen Demodulation ist das leistungsfähigere der beiden Systeme. Ein vollständig digitales System ist so ausgelegt, dass es Phasenänderungen zwischen dem in den beiden Resonatoren zirkulierenden Licht erfasst, um Phasendifferenzen zu minimieren. Dieses System kann die Laserfrequenz beeinflussen und eine ähnliche Stabilität wie andere Frequenzstabilisierungsysteme erreichen.ALPS II is a light-shining-through-a-wall experiment that will search for axion-like particles. These experiments seek to generate and measure axion-like particles in a laboratory using oscillations between photons and axions in the presence of a magnetic field. ALPS II builds on the innovation of its predecessor, ALPS I: optical cavities to enhance the sensitivity. ALPS II will use a production cavity (PC) to increase the number of photons available to generate axion-like particles, and a regeneration cavity (RC) to enhance the probability of the axion-like particles oscillating back into photons. To resonantly enhance the light in the cavities, the input laser light needs to be well-matched to the resonance of the cavities even in the presence of disturbances. Additionally, the resonances of the two cavities must be matched such that the axion-like particles' reconversion probability is enhanced in the RC. The requirement on the frequency noise between the two cavities for ALPS IIc is a root-mean-square (RMS) deviation of smaller than 3.0 Hz. This necessitates the use of high-performance control loops. ALPS IIa is a smaller-scale experiment to test and characterize critical systems for use in the full-scale ALPS IIc. ALPS IIa has the facilities for two cavities to mirror the PC and RC in ALPS IIc. Control systems can be designed and tested to determine their suitability for use in ALPS IIc, and alternative designs can be compared based on their performance in the short-scale experiment. In this thesis, the baseline analog control systems in the ALPS IIa RC are characterized. These include frequency actuation systems for two laser sources, and a length actuation system. The noise of this length actuation system is projected onto the requirements of the resonance overlap between the two cavities and an RMS of 1.0 Hz should be achievable with this system. In order to investigate the viability of digital control systems, two digital frequency control systems are tested: one that replaces the analog servo, and one that replaces the analog demodulation system as well. The RMS of the frequency noise of both digital systems is within a factor of two of the fully analog system. The system with the digital demodulation is the better-performing of the two. A fully digital system is designed to sense phase changes between the light circulating in the two cavities to minimize that phase difference. This system is able to actuate on laser frequency to achieve similar performance to other frequency control systems

Experiments with Trapped Ions and Ultrafast Laser Pulses

Since the dawn of quantum information science, laser-cooled trapped atomic ions have been one of the most compelling systems for the physical realization of a quantum computer. By applying qubit state dependent forces to the ions, their collective motional modes can be used as a bus to realize entangling quantum gates. Ultrafast state-dependent kicks [1] can provide a universal set of quantum logic operations, in conjunction with ultrafast single qubit rotations [2], which uses only ultrafast laser pulses. This may present a clearer route to scaling a trapped ion processor [3]. In addition to the role that spin-dependent kicks (SDKs) play in quantum computation, their utility in fundamental quantum mechanics research is also apparent. In this thesis, we present a set of experiments which demonstrate some of the principle properties of SDKs including ion motion independence (we demonstrate single ion thermometry from the ground state to near room temperature and the largest Schrodinger cat state ever created in an oscillator), high speed operations (compared with conventional atom-laser interactions), and multi-qubit entanglement operations with speed that is not fundamentally limited by the trap oscillation frequency. We also present a method to provide higher stability in the radial mode ion oscillation frequencies of a linear radiofrequency (rf) Paul trap--a crucial factor when performing operations on the rf-sensitive modes. Finally, we present the highest atomic position sensitivity measurement of an isolated atom to date of ~0.5 nm Hz^(-1/2) with a minimum uncertainty of 1.7 nm using a 0.6 numerical aperature (NA) lens system, along with a method to correct aberrations and a direct position measurement of ion micromotion (the inherent oscillations of an ion trapped in an oscillating rf field). This development could be used to directly image atom motion in the quantum regime, along with sensing forces at the yoctonewton [10^(-24) N)] scale for gravity sensing, and 3D imaging of atoms from static to higher frequency motion. These ultrafast atomic qubit manipulation tools demonstrate inherent advantages over conventional techniques, offering a fundamentally distinct regime of control and speed not previously achievable

Phlebot: The Robotic Phlebotomist

Phlebotomy is a routine task, performed over a billion times annually in the United States alone, that is essential for proper diagnosis and treatment. We designed and constructed Phlebot, a robotic assistive device that uses near- infrared imaging and force-feedback to guide a needle into a forearm vein for blood sample collection or intravenous catheterization. Through initial validation on phantoms, we show that it is feasible to automate phlebotomy reliably. We envision the device to be a first major step towards more affordable point-of-care testing and diagnostic healthcare systems. In the long term, we expect that Phlebot will expedite healthcare delivery and drastically reduce needle stick injuries, instances of hemolysis, and infections caused by blood-borne pathogens

NASA Tech Briefs, February 2001

The topics include: 1) Application Briefs; 2) National Design Engineering Show Preview; 3) Marketing Inventions to Increase Income; 4) A Personal-Computer-Based Physiological Training System; 5) Reconfigurable Arrays of Transistors for Evolvable Hardware; 6) Active Tactile Display Device for Reading by a Blind Person; 7) Program Automates Management of IBM VM Computer Systems; 8) System for Monitoring the Environment of a Spacecraft Launch; 9) Measurement of Stresses and Strains in Muscles and Tendons; 10) Optical Measurement of Temperatures in Muscles and Tendons; 11) Small Low-Temperature Thermometer With Nanokelvin Resolution; 12) Heterodyne Interferometer With Phase-Modulated Carrier; 13) Rechargeable Batteries Based on Intercalation in Graphite; 14) Signal Processor for Doppler Measurements in Icing Research; 15) Model Optimizes Drying of Wet Sheets; 16) High-Performance POSS-Modified Polymeric Composites; 17) Model Simulates Semi-Solid Material Processing; 18) Modular Cryogenic Insulation; 19) Passive Venting for Alleviating Helicopter Tail-Boom Loads; 20) Computer Program Predicts Rocket Noise; 21) Process for Polishing Bare Aluminum to High Optical Quality; 22) External Adhesive Pressure-Wall Patch; 23) Java Implementation of Information-Sharing Protocol; 24) Electronic Bulletin Board Publishes Schedules in Real Time; 25) Apparatus Would Extract Water From the Martian Atmosphere; 26) Review of Research on Supercritical vs Subcritical Fluids; 27) Hybrid Regenerative Water-Recycling System; 28) Study of Fusion-Driven Plasma Thruster With Magnetic Nozzle; 29) Liquid/Vapor-Hydrazine Thruster Would Produce Small Impulses; and 30) Thruster Based on Sublimation of Solid Hydrazin

LISA Metrology System - Final Report

Gravitational Waves will open an entirely new window to the Universe, different from all other astronomy in that the gravitational waves will tell us about large-scale mass motions even in regions and at distances totally obscured to electromagnetic radiation. The most interesting sources are at low frequencies (mHz to Hz) inaccessible on ground due to seismic and other unavoidable disturbances. For these sources observation from space is the only option, and has been studied in detail for more than 20 years as the LISA concept. Consequently, The Gravitational Universe has been chosen as science theme for the L3 mission in ESA's Cosmic Vision program. The primary measurement in LISA and derived concepts is the observation of tiny (picometer) pathlength fluctuations between remote spacecraft using heterodyne laser interferometry. The interference of two laser beams, with MHz frequency difference, produces a MHz beat note that is converted to a photocurrent by a photodiode on the optical bench. The gravitational wave signal is encoded in the phase of this beat note. The next, and crucial, step is therefore to measure that phase with µcycle resolution in the presence of noise and other signals. This measurement is the purpose of the LISA metrology system and the subject of this report

Airborne Advanced Reconfigurable Computer System (ARCS)

A digital computer subsystem fault-tolerant concept was defined, and the potential benefits and costs of such a subsystem were assessed when used as the central element of a new transport's flight control system. The derived advanced reconfigurable computer system (ARCS) is a triple-redundant computer subsystem that automatically reconfigures, under multiple fault conditions, from triplex to duplex to simplex operation, with redundancy recovery if the fault condition is transient. The study included criteria development covering factors at the aircraft's operation level that would influence the design of a fault-tolerant system for commercial airline use. A new reliability analysis tool was developed for evaluating redundant, fault-tolerant system availability and survivability; and a stringent digital system software design methodology was used to achieve design/implementation visibility