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Evaluating the Performance of Joint Angle estimation algorithms on an Exoskeleton Mock-Up via a Modular Testing Approach

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SENSORS 2024年第17期24卷 5673页

作者： Pollard, Ryan S. Bass, Sarah M. Schall Jr, Mark C. Zabala, Michael E. Auburn Univ Dept Mech Engn Auburn AL 36849 USA Auburn Univ Dept Ind & Syst Engn Auburn AL 36849 USA

A common challenge for exoskeleton control is discerning operator intent to provide seamless actuation of the device with the operator. One way to accomplish this is with joint angle estimation algorithms and multiple sensors on the human-machine system. However, the question remains of what can be accomplished with just one sensor. The objective of this study was to deploy a modular testing approach to test the performance of two joint angle estimation models-a kinematic extrapolation algorithm and a Random Forest machine learning algorithm-when each was informed solely with kinematic gait data from a single potentiometer on an ankle exoskeleton mock-up. This study demonstrates (i) the feasibility of implementing a modular approach to exoskeleton mock-up evaluation to promote continuity between testing configurations and (ii) that a Random Forest algorithm yielded lower realized errors of estimated joint angles and a decreased actuation time than the kinematic model when deployed on the physical device.

关键词： exoskeleton mock-up estimation algorithms random forest kinematics single sensor joint angles

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Comparative Study of estimation algorithms for Predistorter Coefficients of GaN Power Amplifier 4th

Comparative Study of Estimation Algorithms for Predistorter ...

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4th International Symposium on Ubiquitous Networking (UNet)

作者： Rezgui, Haithem Rouissi, Fatma Ghazel, Adel Univ Carthage GRESCOM Lab SUP COM Cite Technol Commun Ariana Tunisia

ISBN: (纸本)9783030028497;9783030028480

The purpose of this paper is to compare two estimation methods when identifying the coefficients of the Simplified Volterra Series (SVS) model, in order to linearize a class AB GaN Power Amplifier (PA) driven by a 20-MHz LTE-A signal. First, a Digital Predistorter (DPD) design using the cholesky decomposition based inversion method and the Least Square QR (LSQR) algorithm is carried out, and next the performances of each method are analyzed in terms of computational complexity and suppressing distortions capability. The co-simulation test results show that the LSQR performs better than Cholesky decomposition in terms of Adjacent Channel Power Ratio (ACPR) and Normalized Mean Square Error (NMSE) by a margin of 3 dB and 4 dB, receptively.

关键词： RF power amplifier Digital predistortion Volterra series estimation algorithms Look-up table (LUT)

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Quasi coherent overlapping procedure to improve harmonics suppression using single tone estimation algorithms

Quasi coherent overlapping procedure to improve harmonics su...

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Conference on Precision Electromagnetic Measurements (CPEM)

作者： Lapuh, Rado Voljc, Bostjan Kokalj, Miha Lindic, Matjaz Svetik, Zoran Slovenian Inst Qual & Metrol Ljubljana Slovenia Metrol Inst Republ Slovenia Celje Slovenia

ISBN: (纸本)9781467391344

This paper describes the procedure to reduce an estimation bias of interpolated DFT and single-model sine-fit algorithms. estimation bias reduction of more than an order of magnitude is attainable. The procedure does not modify the estimation algorithm itself and additional knowledge of the measurement system or additional sampled points are not required.

关键词： Measurement sampling estimation algorithms harmonic distortion estimation error uncertainty

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Vehicle Trajectory estimation Using a High-Gain Multi-Output Nonlinear Observer

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IEEE TRANSACTIONS ON INTELLIGENT TRANSPORTATION SYSTEMS 2024年第6期25卷 5733-5742页

作者： Alai, Hamidreza Zemouche, Ali Rajamani, Rajesh Univ Minnesota Twin Cities Dept Mech Engn Minneapolis MN 55455 USA Univ Lorraine CRAN UMR7039 Nancy France

This paper focuses on the design of a multi-output high gain observer for a vehicle trajectory tracking application. Tracking the trajectories of other vehicles on the road is needed for many applications ranging from collision avoidance to autonomous driving. Previously, such trajectory tracking has been done using linearized dynamic models, interacting-multiple-model (IMM) filters, or else by using LMI-based nonlinear observers. These estimation techniques suffer from some crucial shortcomings. Hence, this paper develops a high gain nonlinear observer for this application. The high gain observer approach offers the advantages of guaranteed feasibility and stability with just one constant observer gain for a wide range of motion. The challenges of transforming the vehicle dynamic model into the required companion form for applying the high gain observer technique are addressed. A coordinate transformation that allows for varying velocity and varying slip angle is shown to be appropriate. The high gain observer methodology for a dynamic system with multiple outputs is presented. Finally, simulation and experimental results on vehicle tracking are demonstrated. The experimental results show that, with a high gain observer, vehicle trajectories that span a large range of orientations can be accurately tracked using just one constant observer gain.

关键词： Observers Radar tracking Vehicle dynamics Trajectory Stability criteria Laser stability Kalman filters Vehicle trajectory estimation vehicle control filters estimation algorithms nonlinear observer e-scooter

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Development of an Autonomous Measurement System for estimation of Snow Profile on Road Surfaces

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2023年第9期72卷 11169-11183页

作者： Espindola, Andre Rajamani, Rajesh Univ Minnesota Dept Mech Engn 111 Church St SE Minneapolis MN 55455 USA

This paper presents the development of a novel prototype system to measure the profile of snow and detect ice on road surfaces. While researchers have previously developed methods to estimate the tire-road friction coefficient, methods to create a high resolution map of snow cover and ice on roads have not been developed. The prototype and data processing methods presented in this study provide a potential solution that would greatly benefit winter road maintenance teams. Having a device capable of creating a detailed map of snow and ice cover on roads would allow for more efficient plowing and salt deployment, better informing of the public about current road conditions, as well as better analysis of current plowing techniques to improve winter road maintenance operations. The measurement of the snow profile is based on the use of two types of inexpensive ranging sensors mounted on a rotationally controlled stepper motor platform. The technical challenges addressed in the development include analysis of the scan path over which the system scans the road, differentiation between asphalt, concrete, and snow surfaces using reflection amplitudes, accurate transformation of raw distance measurements to inertial coordinates, and identification of the Euler angles of the sensors using parameters associated with the scanned surface profile. Extensive experimental results and test data are presented, which show that the system is capable of measuring the snow profile on a road with an accuracy of +/- 1 cm when a reasonable portion of bare road is visible, and +/- 2 cm when only small portions of bare road are visible.

关键词： estimation algorithms ice detection laser sensors snow profile winter road maintenance

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Adaptive Algorithm for Fast 3D Characterization of Magnetic Sensors

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SENSORS 2025年第4期25卷 995-995页

作者： Boueke, Moritz Hoffmann, Johannes Ellrichmann, Mark Bergholz, Robert Schmidt, Gerhard Univ Kiel Fac Engn Dept Elect & Informat Engn D-24143 Kiel Germany Univ Kiel Univ Hosp Schleswig Holstein Dept Internal Med 1 Campus Kiel D-24105 Kiel Germany Univ Kiel Univ Hosp Schleswig Holstein Dept Pediat Surg Campus Kiel D-24105 Kiel Germany

Magnetic sensors are highly relevant in clinical and industrial applications such as localization tasks and geological investigations. The spatial behavior of these sensors is of great interest for accurate forward modeling and the consequential possibilities for sophisticated applications, e.g., solutions to inverse problems. In this contribution, we present a novel characterization approach using adaptive system identification approaches. We utilize a gradient-based algorithm for estimating impulse and corresponding frequency responses for a directivity analysis in 1D, 2D, and 3D. For this, we built a triaxial Helmholtz coil setup to generate a 3D directive field. This is controlled by an algorithm that exploits similarities in sensor behavior with respect to small differences in excitation field angles. We found advantages for a controlled adaptation, with faster convergence and a smaller system distance between estimations and measurements with a proposed control based on the contraction-expansion approach (CEA). With runtimes averaging less than 1.5 s per direction for full impulse response estimation, this proof of concept shows the potential of the proposed algorithm for enabling a feasible frequency and directivity characterization method.

关键词： magnetic sensor characterization estimation algorithms adaptive filters NLMS control magnetic field steering impulse response frequency response directivity

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Experimental validation of direction of arrival estimation for high chirp-rate linear frequency modulated radar signals

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IET RADAR SONAR AND NAVIGATION 2021年第6期15卷 627-640页

作者： Mulinde, Ronald Attygalle, Manik Aziz, Syed Mahfuzul Univ South Australia UniSA STEM Mawson Lakes SA 5095 Australia Def Sci & Technol Grp Cyber & Elect Warfare Div Adelaide SA Australia

Direction of arrival (DOA) estimation for signals with large time-bandwidth products is very important in modern communication and radar systems. Traditional narrowband DOA estimation algorithms are not accurate for such wideband signals. Further complexities arise with non-stationary signals, for example, high chirp-rate linear frequency modulated (LFM). These complexities imply that achieving real-time performance with good DOA estimation accuracy is a challenge. This article uses experimentally acquired data on high chirp-rate LFM signals to validate a channelised version of MUltiple SIgnal Classification (MUSIC) for DOA estimation. This technique eliminates pre-processing and incoherently combines spatial pseudospectra from individual frequency channels to obtain a single accurate estimate and has much less computational complexity compared to coherent techniques. LFM signals of up to 500 MHz bandwidth and chirp rates of up to 50 MHz/mu s have been used in the investigations and results show accurate DOA estimation at low SNR (0 dB). This technique is suitable for even wider operational bandwidths and low latency implementations. To the best of our knowledge, this is the first time DOA estimation for such high chirp-rate LFM signals has been validated using real experimental data which is also corroborated with validation using synthetic data.

关键词： single accurate estimate individual frequency channels estimation algorithms Signal processing and detection experimental validation arrival estimation Radar equipment, systems and applications nonstationary signals wideband signals modern communication chirp-rate LFM signals time-bandwidth products chirp-rate linear frequency good DOA estimation accuracy frequency modulation radar systems experimentally acquired data radar signals bandwidth 500.0 MHz MUltiple SIgnal Classification array signal processing accurate DOA estimation chirp rates Interpolation and function approximation (numerical analysis) FM radar loss 0.0 dB direction-of-arrival estimation signal classification

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Parameter estimation of two classes of nonlinear systems with non-separable nonlinear parameterizations☆

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AUTOMATICA 2024年 163卷

作者： Ortega, Romeo Bobtsov, Alexey Nikolaev, Nikolay Costa-Castello, Ramon ITAM Dept Elect & Elect Engn Mexico City Mexico Hangzhou Dianzi Univ Sch Automat Hangzhou 310005 Zhejiang Peoples R China ITMO Univ Dept Control Syst & Robot Kronverkskiy Ave 49 St Petersburg 197101 Russia IPME Lab Control Complex Syst VO Bolshoj Pr 61 St Petersburg 199178 Russia Univ Politecn Catalunya UPC Catalonia Barcelona Spain

In this paper we address the challenging problem of designing globally convergent estimators for the parameters of nonlinear systems containing an exponential function whose power depends on unknown parameters. This class of non-separable nonlinearities appears in many practical applications, and none of the existing parameter estimators is able to deal with them in an efficient way. Our main technical contribution is the development of a lifting procedure for non-separable nonlinearly parameterized regressor equations to obtain separable ones, to which we can apply a recently reported estimation procedure. This is illustrated with a human musculoskeletal dynamics problem. The procedure does not assume that the parameters leave in known compact sets, that the nonlinearities satisfy some Lipschitzian properties, nor rely on injection of high-gain or the use of complex, computationally demanding methodologies. Instead, we propose to design a classical on-line estimator whose dynamics is described by an ordinary differential equation given in a compact precise form. (c) 2024 Elsevier Ltd. All rights reserved.

关键词： Nonlinear systems Observers estimation algorithms Regression estimates Excitation

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estimation of Particulate Backscattering Coefficient in Turbid Inland Water Using Sentinel 3A-OLCI Image

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IEEE JOURNAL OF SELECTED TOPICS IN APPLIED EARTH OBSERVATIONS AND REMOTE SENSING 2021年 14卷 8577-8593页

作者： Xu, Jiafeng Bian, Yingchun Lyu, Heng Miao, Song Li, Yunmei Liu, Huaiqing Xu, Jie Nanjing Normal Univ Key Lab Virtual Geog Environm Educ Minist Nanjing 210023 Jiangsu Peoples R China Jiangsu Ctr Collaborat Invocat Geog Informat Reso Nanjing 210023 Peoples R China

The particulate backscattering coefficient (b(bp)) plays an important role in the underwater light field. However, it is difficult to accurately estimate b(bp)(lambda) in turbid inland water with complex optical properties. To accurately estimate the backscattering coefficients in inland water, a simple classification method based on the shape of remote sensing reflectance was first proposed to distinguish two water types (i.e., water type 1 and water type 2) with different backscattering characteristics. Then, trigonometric functions were developed to simulate the backscattering coefficients at all bands in water type 1 and the backscattering coefficients in the visible band of water type 2, whereas a linear function was built to estimate the backscattering coefficients in the near-infrared band of water type 2. The proposed algorithm was compared with four state-of-the-art methods and validated by an independently measured dataset of three lakes in the middle and lower reaches of the Yangtze River in 2020. The results showed that the proposed algorithm performed well in inland waters, with all mean absolute percentage errors < 40% and root-mean-square errors < 0.25 m(-1). Finally, the algorithm was applied to Ocean and Land Color Instrument images from 2016 to 2020 in Lake Taihu and Lake Hongze. It was found that the backscattering coefficients in Lake Taihu and Lake Hongze showed opposite seasonal variation trends, and the b(bp)(676) in Lake Hongze began to decrease since 2017, whereas no obvious interannual variation was observed in Taihu Lake in recent five years.

关键词： Backscatter Lakes Water Remote sensing Reflectivity Atmospheric measurements estimation estimation algorithms inland waters ocean and land color instrument (OLCI) images particulate backscattering coefficient

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Comparative Analysis of the Noise Immunity of algorithms for Reconstructing Seabed Geoacoustic Parameters by the Coherent Sounding Technique

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ACOUSTICAL PHYSICS 2021年第4期67卷 381-396页

作者： Kalinina, V., I Smirnov, I. P. Khilko, A., I Malekhanov, A., I Russian Acad Sci Inst Appl Phys Nizhnii Novgorod 603950 Russia Nizhnii Novgorod State Univ Nizhnii Novgorod 603950 Russia

Based on a previously developed numerical model, a comparative analysis of the efficiency of algorithms for reconstructing the geoacoustic parameters for a seabed with a layered structure is carried out based on probing signals in a synchronized sequence of mutually coherent complex signals. The algorithms differ in how the multiparameter criterion function is constructed;when its extremum is found, it yields an estimate of the required parameters. As such functions, the root-mean-square norm of the signal mismatch, functionals of generalized MUSIC methods, and neuronlike convolution are used. The stability of the estimates obtained (in terms of the mean bias and variance of deviations from the true value) is investigated by stochastic modeling as a function of the signal-to-noise ratio at the receiver inputs. It is shown that the considered algorithms exhibit significantly different noise immunity, which in turn depends on which particular parameter is to be estimated.

关键词： layered-heterogeneous seabed geoacoustic parameters seismoacoustic probing coherent signals parameter estimation criterion function estimation algorithms stochastic modeling

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