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On the Effect of Stabilization Methods for Quaternion Invariants on the Uncertainty in Optimization-based estimation

On the Effect of Stabilization Methods for Quaternion Invari...

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Joint Meeting of the 2nd IFAC Workshop on Linear Parameter Varying Systems (LPVS) / 9th IFAC Symposium on Robust Control Design (ROCOND)

作者： Girrbach, Fabian Hol, Jeroen D. Zandbergen, Raymond Verschueren, Robin Bellusci, Giovanni Diehl, Moritz Xsens Technol BV NL-7521 PR Enschede Netherlands Univ Freiburg Dept Microsyst Engn IMTEK D-79110 Freiburg Germany

The handling of 3D orientations is a common element in many problems that arise in the estimation and control of dynamic systems. Over-parametrizations such as unit quaternions are commonly used to avoid singularities but come with the property of an invariant which needs to be preserved. By using numerical optimization methods, these invariants are subject to numeric errors and require stabilization. In this work, we adopt methods known from optimal control for the problem of state estimation. We present an optimization-based attitude estimator using the measurements of an inertial measurement unit and evaluate the performance of a first order stabilization of the invariant by modifying the dynamics. The uncertainties of the estimator are analyzed for different configurations of the proposed stabilization. Finally, we show how the stabilization affects the estimation of parameters and justify the use of an additional equality constraint for the invariant to yield more robust and consistent results. (C) 2018, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

关键词： estimation algorithms optimal estimation invariants attitude algorithms

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Refractive Index estimation from Spectral Measurements of a Plasmonic Glucose Sensor and Wavelength Selection

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IFAC-PapersOnLine 2017年第1期50卷 4406-4411页

作者： Teutsch T. Mesch M. Giessen H. Tarín C. Institute for System Dynamics University of Stuttgart Stuttgart 70569 Germany 4th Physics Institute University of Stuttgart Stuttgart 70569 Germany

Noninvasive glucose monitoring is a desired objective in diabetes therapy and monitoring the glucose levels in the tear fluid is one possibility to approach this objective. The plasmonic glucose sensor presented within this work consists of metal nanostructures which cause a resonance in the optical response and the resonance wavelength position depends on the refractive index of the surrounding. Glucose selectivity is guaranteed by functionalizing the sensor with a hydrogel that swells with glucose and thus changes its refractive index. The focus of this work lies on the relationship between the refractive index and the resulting transmission spectra of the sensor. Based on this understanding, an estimation algorithm is presented, which provides a refractive index value for any measured spectrum. It is shown that this new estimation algorithm improves previous results. For a mobile application of the sensor, the transmission can only be measured at few discrete wavelengths rather than the whole spectrum. The choice of these discrete wavelengths has a huge influence on the estimation results. The developed estimation algorithm is used to build an objective function to determine the best wavelengths via sequential forward feature selection. The results of the feature selection show that even reducing the discrete wavelengths to a number of four, refractive index estimation can be performed with a relative error below 0.05%. © 2017

关键词： biomedical systems estimation algorithms input estimation medical applications optical response optical spectroscopy reduction sensors signal analysis

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Refractive Index estimation from Spectral Measurements of a Plasmonic Glucose Sensor and Wavelength Selection

Refractive Index Estimation from Spectral Measurements of a ...

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20th World Congress of the International-Federation-of-Automatic-Control (IFAC)

作者： Teutsch, Tanja Mesch, Martin Giessen, Harald Tarin, Cristina Univ Stuttgart Inst Syst Dynam D-70569 Stuttgart Germany Univ Stuttgart Inst Phys 4 D-70569 Stuttgart Germany

关键词： estimation algorithms sensors signal analysis optical spectroscopy optical response input estimation reduction biomedical systems medical applications

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Model Ship Control and estimation of Full-scale Propeller Torque in Wind and Waves

Model Ship Control and Estimation of Full-scale Propeller To...

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11th IFAC Conference on Control Applications in Marine Systems, Robotics, and Vehicles (CAMS)

作者： Ueno, Michio Suzuki, Ryosuke Tsukada, Yoshiaki Natl Maritime Res Inst Mitaka Tokyo 1810004 Japan

This paper presents free-running model ship test data estimating full-scale propeller torque fluctuating in wind and waves. The model ship control using the auxiliary thruster ensures the similarity of model ship motion to full scale that leads the similar propeller situation. The wind load simulator controls six duct fans on the model ship for simulating the wind loads. The estimation algorithm converts the measured model propeller torque to full scale assuming no scale effect on the wave component in the effective inflow velocity to propeller. The analysis reveals the differences of the fluctuating propeller torque between model and full-scale ships. (C) 2018, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

关键词： Model ship control Scale effect Wind and waves Propeller torque estimation algorithms

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estimation of a variable rate of depreciation: A dummy variable approach

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Structural Change and Economic Dynamics 1997年第3期8.0卷 319-325页

作者： Prucha, Ingmar Department of Economics University of Maryland Tydings Hall College Park MD 20742 United States

Many important economic problems require measures of both physical and R&D capital. Except for some recent studies, there have been relatively few contributions in the literature that provide econometric estimates for the depreciation rates of physical and R&D capital. One reason for the relative paucity of such econometric studies may be that if the depreciation rates are viewed as unknown parameters, or as a functions of unknown parameters, then the corresponding stocks of physical and R&D capital are also unobserved, resulting in a formidable estimation problem. In the past, econometric estimates of the depreciation rates of physical and R&D capital were typically obtained from self-programmed estimation algorithms. In this note, an approach is introduced that permits the econometric estimation of constant and variable rates of depreciation of physical and R&D capital using standard econometric packages. © 1997 Elsevier Science B.V.

关键词： Depreciation rates estimation algorithms Physical and R&D capital

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Identifiability and Parameter estimation of Linear Continuous-time Systems under Irregular and Random Sampling

Identifiability and Parameter Estimation of Linear Continuou...

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17th IFAC Symposium on System Identification (SYSID 2015)

作者： Mu, Biqiang Guo, Jin Wang, Le Yi Yin, George Xu, Lijian Zheng, Wei Xing Chinese Acad Sci Key Lab Syst & Control Beijing 100190 Peoples R China Univ Sci & Technol Beijing Sch Automat & Elect Engn Beijing 100083 Peoples R China Wayne State Univ Dept Elect & Comp Engn Detroit MI 48202 USA Wayne State Univ Dept Math Detroit MI 48202 USA State Univ New York Farmingdale State Coll Dept Elect & Comp Engn Technol Farmingdale NY 11735 USA Univ Western Sydney Sch Comp Engn & Math Penrith NSW 2751 Australia

This paper considers the problem of identifiability and parameter estimation of single-input-single-output, linear, time-invariant, stable, continuous-time systems under irregular and random sampling schemes. Conditions for system identifiability are established under inputs of exponential polynomial types and a tight bound on sampling density. Identification algorithms of Gauss-Newton iterative types are developed to generate convergent estimate sequences. When the sampled output is corrupted by observation noises, input design, sampling times, and convergent algorithms are intertwined. Persistent excitation (PE) conditions for strongly convergent algorithms are derived. Unlike the traditional identification, the PE conditions under irregular and random sampling involve both sampling;times and input values. Under the given PE conditions, iterative and recursive algorithms are developed to estimate the original continuous-time system parameters. The corresponding convergence results are obtained. Several simulation examples are displayed to verify the theoretical results. (C) 2015, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

关键词： Linear Continuous-time Systems irregular sampling identifiability nonlinear least square estimation algorithms convergence and asymptotical normality

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Angular velocity estimation from incremental encoder measurements in the presence of sensor imperfections

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IFAC-PapersOnLine 2017年第1期50卷 5979-5984页

作者： Aguado-Rojas M. Pasillas-Lépine W. Loría A. De Bernardinis A. Université Paris-Sud Université Paris-Saclay L2S-CentraleSupelec Gif-sur-Yvette 91192 France CNRS L2S-CentraleSupelec Gif-sur-Yvette 91192 France SATIE IFSTTAR-LTN Versailles 78000 France

In the area of traction and brake control, measurements of the rotational velocity of the wheels are often affected by large periodic disturbances that arise from sensor imperfections and degrade the performance of any closed-loop control algorithm. The aim of our paper is to address this problem. First, we present a detailed analysis of the most common sensor imperfections and their effect on their measured velocity. Then, we propose an estimation scheme that greatly reduces the periodic disturbances in order to provide a better estimate of the velocity, and we validate it via numerical simulations and experiments. © 2017

关键词： adaptive algorithms encoders estimation algorithms least-squares method measurement noise parameter estimation Velocity measurements

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estimation of Grid Frequency in Disturbed Converter-Based Power Systems by PLL State Variable Feedback 21st

Estimation of Grid Frequency in Disturbed Converter-Based Po...

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21st IFAC World Congress on Automatic Control - Meeting Societal Challenges

作者： Goldschmidt, Nico Schulte, Horst Univ Appl Sci HTW Berlin Dept Engn 1 Control Engn Grp Wilhelminenhofstr 75A D-12459 Berlin Germany

Fast real-time estimation of the grid frequency is essential for stable operation of renewable converter-based sources in future power systems. Therefore this paper presents a new phase-locked loop for the estimation of time-dependent frequencies in unbalanced power systems with harmonics. The proposed frequency estimation method consists of two signal processing steps: In the first step, a least mean square estimator reconstructs the fundamental sinusoidal signal from the measured three-phase grid voltage and splits it into positive, negative and zero sequence components. In the second step, the resulting first harmonic three-phase positive sequence is converted into the synchronous reference frame in the form of a phase-locked loop using a state feedback controller scheme to reconstruct the current grid frequency. Here the controller output is equivalent to the signal to be reconstructed. The feedback controller design is based on linear matrix inequalities where the requirements are explicitly considered. The capability of proposed state feedback phase-locked loop is demonstrated by full scaled electro magnetic transient simulations. Copyright (C) 2020 The Authors.

关键词： estimation algorithms Phase-locked loop Power system control Renewable energy systems Convex optimisation

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State estimation in the Presence of Intermittent Actuator Faults 21st

State Estimation in the Presence of Intermittent Actuator Fa...

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21st IFAC World Congress on Automatic Control - Meeting Societal Challenges

作者： Strandt, Alia R. Schneider, Susan C. Yaz, Edwin E. Dept Elect & Comp Engn Milwaukee WI 53233 USA

The problem of intermittent, random actuator faults is important in many applications, such as in networked systems, in which there may be intermittent losses of communication between the actuators and the plant. However, state estimation of such systems is rarely addressed, with the majority of the work focusing on fault-tolerant control. In this work, the Kalman filter is modified for state estimation of systems with intermittent actuator faults when the fault rate is known. The proposed estimator is then extended to the case when the actuator fault rate is unknown using the multiple model estimation algorithm. In addition, a sketch of a proof of convergence for this technique is provided. Several simulations involving a DC motor that experiences random actuator faults demonstrate the effectiveness of the proposed techniques. Copyright (C) 2020 The Authors.

关键词： Actuator failures Parameter estimation estimation algorithms Stochastic parameters State estimation

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Bayesian Fill Volume estimation Based on Point Level Sensor Signals 21st

Bayesian Fill Volume Estimation Based on Point Level Sensor ...

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21st IFAC World Congress on Automatic Control - Meeting Societal Challenges

作者： Zumsande, Johannes Kortmann, Karl-Philipp Wielitzka, Mark Ortmaier, Tobias Leibniz Univ Hannover Inst Mechatron Syst Hannover Germany

In dry bulk and fluid processing, the composites are usually stored in hoppers, tanks, or other containers. Due to the economic advantages, binary point level sensors, which detect fill level exceeding, are widely used for process monitoring and control. In this paper, we propose different filters for estimating the probability distribution of the fill volume based on a time-variant measurement distribution and a stochastic physical model with white process noise. A filter based on the model prediction with separated measurement update and two Bayesian particle filters are proposed and compared with a simulated ground truth. The performance measures are the root-mean-square error, the precision of the 95 % and 75 % credible intervals, and the average value of the estimated probability density function at the simulated fill volumes. Copyright (C) 2020 The Authors.

关键词： Bayesian filter data fusion probabilistic models stochastic approximation estimation algorithms

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