Attitude Control of a 2-DOF Helicopter System with Input Quantization and Delay

Author's accepted manuscript© 2022 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.In this paper the attitude tracking control problem of a 2 degrees-of-freedom helicopter system with network induced constraints is studied. A predictor feedback control law is developed to compensate a known delay in the communication, where the inputs are quantized before transmitted over the network. Stability of the closed-loop system is established, where tracking is achieved with bounded tracking errors due to the network issues. The developed predictor-based controller is experimentally tested on the helicopter system, where we demonstrate that tracking is achieved in presence of both input delay and quantization.acceptedVersio

Bør Norges bank ta mer hensyn til penge- og kredittvekst i rentesettingen? Teoretiske betraktninger og empiriske analyser av sammenhengen mellom produksjonsgap, pengemengde- og kredittvekst i Norge

I denne oppgaven er formålet å vurdere om Norges Bank bør ta hensyn til vekst i pengemengde og kreditt i rentesettingen. Bakgrunnen er en antagelse om at pengepolitikken som er ført siden fleksibel inflasjonsstyring ble introdusert som pengepolitisk regime i mars 2001, ikke har fungert tilfredsstillende. Produksjonsgapet representerer en evaluering av landets ressursutnyttelse og inneholder i likhet med inflasjonen viktig informasjon om utviklingen i økonomien. Pengemengde- og kredittvekst er variabler som allerede følges av Norges Bank som en del av et større variabelsett og som har fått mye oppmerksomhet fordi utviklingen av disse variablene har vist seg å være sammenfallende med økonomiske forstyrrelser og kriser. Det som står sentralt i denne oppgaven er å vurdere om variablene i tillegg kan benyttes som indikatorer for produksjonsgapet. Sammenhengen mellom pengemengde-, kreditt, og produksjonsgap i Norge vil bli belyst gjennom teori og empiriske analyser. Ved å studere utviklingen i de ulike gapene vurderes det om disse innehar egenskaper som kan predikere utviklingen i konjunkturene. Avslutningsvis vil det bli argumentert for at kreditt og pengemengde er variabler som bør tillegges mer vekt i pengepolitikken gjennom en utvidelse av mandatet, og det vil bli presentert et forslag for en ny tapsfunksjon der disse variablene tas hensyn til

Er det amerikanske resiliensprogrammet CSF2 godt egnet for å utvikle resiliens hos soldater?

Det norske forsvaret gjennomfører jevnlig trening og øving, eksempelvis feltøvelser, for å opprettholde og øke egen robusthet. Resiliens blir derimot ikke vektlagt i samme omfang, og det norske forsvaret har ikke strukturerte programmer for å øke grad av resiliens blant sitt personell. Som beskrevet tidligere har vår viktigste alliert, USA, investert store summer i å utvikle et resiliensprogram. Vi ønsker derfor å utforske det amerikanske resiliensprogrammet CSF2, og vurdere om et slik program vil kunne være overførbart for det norske forsvaret. Problemstillingen for oppgaven er som følger: Er det amerikanske resiliensprogrammet Comprehensive Soldier and Family Fitness (CSF2) godt egnet for å utvikle resiliens hos soldater?updatedVersio

When is the discretization of a spatially distributed system good enough for control?

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Nonlinear Model-Based Control of Unstable Wells

This paper illustrates the potential of nonlinear model-based control applied for stabilization of unstable flow in oil wells. A simple empirical model is developed that describes the qualitative behavior of the downhole pressure during severe riser slugging. A nonlinear controller is designed by an integrator backstepping approach, and stabilization for open-loop unstable pressure setpoints is demonstrated. The proposed backstepping controller is shown in simulations to perform better than PI and PD controllers for low pressure setpoints, and is in addition easier to tune. Operation at a low pressure setpoint is desirable since it corresponds to a high production flow rate. The simulation results are presented to illustrate the effectiveness of proposed control scheme

Dynamically Correct Formulations of the Linearised Navier-Stokes Equations

Motivated by the need to efficiently obtain low-order models of fluid flows around complex geometries for the purpose of feedback control system design, this paper considers the effect on system dynamics of basing plant models on different formulations of the linearised Navier-Stokes equations. We consider the dynamics of a single computational node formed by spatial discretisation of the governing equations in both primitive variables (momentum equation & continuity equation) and pressure Poisson equation (PPE) formulations. This reveals fundamental numerical differences at the nodal level, whose effects on the system dynamics at the full system level are exemplified by considering the corresponding formulations of a two-dimensional (2D) channel flow, subjected to a variety of different boundary conditions

Finite-element-method (FEM) model generation of time-resolved 3D echocardiographic geometry data for mitral-valve volumetry

INTRODUCTION: Mitral Valve (MV) 3D structural data can be easily obtained using standard transesophageal echocardiography (TEE) devices but quantitative pre- and intraoperative volume analysis of the MV is presently not feasible in the cardiac operation room (OR). Finite element method (FEM) modelling is necessary to carry out precise and individual volume analysis and in the future will form the basis for simulation of cardiac interventions. METHOD: With the present retrospective pilot study we describe a method to transfer MV geometric data to 3D Slicer 2 software, an open-source medical visualization and analysis software package. A newly developed software program (ROIExtract) allowed selection of a region-of-interest (ROI) from the TEE data and data transformation for use in 3D Slicer. FEM models for quantitative volumetric studies were generated. RESULTS: ROI selection permitted the visualization and calculations required to create a sequence of volume rendered models of the MV allowing time-based visualization of regional deformation. Quantitation of tissue volume, especially important in myxomatous degeneration can be carried out. Rendered volumes are shown in 3D as well as in time-resolved 4D animations. CONCLUSION: The visualization of the segmented MV may significantly enhance clinical interpretation. This method provides an infrastructure for the study of image guided assessment of clinical findings and surgical planning. For complete pre- and intraoperative 3D MV FEM analysis, three input elements are necessary: 1. time-gated, reality-based structural information, 2. continuous MV pressure and 3. instantaneous tissue elastance. The present process makes the first of these elements available. Volume defect analysis is essential to fully understand functional and geometrical dysfunction of but not limited to the valve. 3D Slicer was used for semi-automatic valve border detection and volume-rendering of clinical 3D echocardiographic data. FEM based models were also calculated. METHOD: A Philips/HP Sonos 5500 ultrasound device stores volume data as time-resolved 4D volume data sets. Data sets for three subjects were used. Since 3D Slicer does not process time-resolved data sets, we employed a standard movie maker to animate the individual time-based models and visualizations. Calculation time and model size were minimized. Pressures were also easily available. We speculate that calculation of instantaneous elastance may be possible using instantaneous pressure values and tissue deformation data derived from the animated FEM