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49th Annual Conference of the IEEE Industrial Electronics Society, IECON 2023

作者： Xenya, Michael Christopher Cortesao, Rui Institute of Systems and Robotics University of Coimbra Electrical and Computer Engineering Department Coimbra3030-290 Portugal FOE GCTU PMB100 Accra Ghana

ISBN: (纸本)9798350331820

Metal mold casting for many application areas remains imperfect since this involves the control of numerous factors that affect workpiece quality. Surface roughness which remains one of the many issues related to metal mold cast is often mitigated by means of grinding and polishing. As many attempts are being made to address this challenge through robot-assisted techniques, we focus on rapid mold polishing using the Franka Emika (FE) robot and its programming resources, including a built-in impedance control architecture. To accomplish the objective, mold surface segmentation is necessary. For each segment, the polishing approach is based on surface normals, relative motion, and torque sensor data. Results were obtained with open platform communication-unified architecture (opc-ua) client and server that record torque and force data. Results show that tuning internal impedance control parameters for polishing tasks is feasible. © 2023 IEEE.

关键词： Polishing

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Exploring workout repetition counting and validation through deep learning 17th

Exploring workout repetition counting and validation through...

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17th International Conference on Image Analysis and Recognition, ICIAR 2020

作者： Ferreira, Bruno Ferreira, Pedro M. Pinheiro, Gil Figueiredo, Nelson Carvalho, Filipe Menezes, Paulo Batista, Jorge Institute of Systems and Robotics Department of Electrical and Computer Engineering University of Coimbra Coimbra Portugal Nixfuste Nova Porto Portugal Prozis.Tech Maia Portugal

ISBN: (纸本)9783030503468

Studying human motion from images and videos has turned into an interesting topic of research given the recent advances in computer vision and deep learning algorithms. When focusing on the automatic procedure of tracking physical exercises, cameras can be used for full human pose estimation in relation to worn sensors. In this work, we propose a method for workout repetition counting and validation based on a set of skeleton-based and deep semantic features that are obtained from a 2D human pose estimation network. Given that some of the individuals’ body parts might be occluded throughout physical exercises, we also perform a multi-view analysis on supporting cameras to improve our recognition rates. Nevertheless, the obtained results for a single-view approach show that we are able to count valid repetitions with over 90% precision scores for 4 out of 5 considered exercises, while recognizing more than 50% of the invalid ones. © Springer Nature Switzerland AG 2020.

关键词： Cameras

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Revisiting the K-nn algorithm for obstetric image segmentation

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International Journal of Hybrid Intelligent systems 2021年第1-2期17卷 1-13页

作者： Salgado, P. Azevedo Perdicoúlis, T.-P. CITAB-Department de Engenharias Ect Utad Quinta de Prados Vila Real Portugal Department of Electrical and Computer Engineering Ect Utad of Institute of Systems and Robotics University of Coimbra Coimbra Portugal

Medical image techniques are used to examine and determine the well-being of the foetus during pregnancy. Digital image processing (DIP) is essential to extract valuable information embedded in most biomedical signals. Afterwords, intelligent segmentation methods, based on classifier algorithms, must be applied to identify structures and relevant features from previous data. The success of both is essential for helping doctors to identify adverse health conditions from the medical images. To obtain easy and reliable DIP methods for foetus images in real-time, at different gestational ages, aware pre-processing needs to be applied to the images. Thence, some data features are extracted that are meant to be used as input to the segmentation algorithms presented in this work. Due to the high dimension of the problems in question, assemblage of the data is also desired. The segmentation of the images is done by revisiting the K-nn algorithm that is a conventional nonparametric classifier. Besides its simplicity, its power to accomplish high classification results in medical applications has been demonstrated. In this work two versions of this algorithm are presented (i) an enhancement of the standard version by aggregating the data apriori and (ii) an iterative version of the same method where the training set (TS) is not static. The procedure is demonstrated in two experiments, where two images of different technologies were selected: a magnetic resonance image and an ultrasound image, respectively. The results were assessed by comparison with the K-means clustering algorithm, a well-known and robust method for this type of task. Both described versions showed results close to 100% matching with the ones obtained by the validation method, although the iterative version displays much higher reliability in the classification. © 2021 - IOS Press. All rights reserved.

关键词： Feature extraction image segmentation K-nn algorithm magnetic resonance image ultrasound image

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State estimation for systems with implicit outputs for the integration of vision and inertial sensors

State estimation for systems with implicit outputs for the i...

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44th IEEE Conference on Decision and Control, and the European Control Conference, CDC-ECC '05

作者： Aguiar, A. Pedro Hespanha, João P. ISR/IST Institute for Systems and Robotics Instituto Superior Técnico Torre Norte 8 Av. Rovisco Pais 1049-001 Lisboa Portugal Department of Electrical and Computer Engineering University of California Santa Barbara CA 93106-9560 United States

ISBN: (纸本)0780395689

This paper addresses the state estimation of a system with implicit outputs. We formulate the problem in the so-called deterministic H ∞ filtering setting by computing the value of the state that minimizes the induced L2 -gain from disturbances to estimation error, while remaining compatible with the past observations. To avoid weighting the distant past as much as the present, a forgetting factor is also introduced. We show that, under appropriate observability assumptions, the optimal estimate converges globally asymptotically to the true value of the state in the absence of noise and disturbance. In the presence of noise, the estimate converges to a neighborhood of the true value of the state. We apply these results to the estimation of position and attitude of an autonomous vehicle using measurements from an inertial measurement unit (IMU) and a monocular charged-coupled-device (CCD) camera attached to the vehicle. © 2005 IEEE.

关键词： State estimation

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Webcam-Based Tachometer for In-Field Induction Motor Load Estimation

Webcam-Based Tachometer for In-Field Induction Motor Load Es...

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International Conference on electrical Machines

作者： Fernando J. T. E. Ferreira Fernando J. P. Lopes Institute of Systems and Robotics (ISR-UC) Department of Electrical and Computer Engineering University of Coimbra Dep. of Electrical Engineering Polytechnic Institute of Coimbra (IPC/ISEC)

ISBN: (纸本)9781509025398

Rotational speed measurement is a key issue in most industries, either for process control, characterization or fault diagnosis. In electric motor driven systems it can be used, for example, to estimate the motor load or pulley-belt transmission slip. Encoders and resolvers are typically used for continuous speed monitoring, requiring mechanical coupling with the rotating shaft/part. If the speed is to be measured at a given instant or during a few moments, noninvasive contactless optical tachometers can be used, using optical reflection or stroboscopic principles. In most cases, stroboscopic tachometers require no reflective elements/strips in the rotating part. However, if the user wants to continuously measure the speed of a given rotating part during the audit/characterization period, with real-time data logging and without sticking reflective strips or introducing shaft-coupled encoders/resolvers, there is no low-cost commercial solution to perform such task. For example, if the user's aim is to continuously estimate the load variation of an induction motor over a day or week, on the basis of the slip/speed value, it is not possible with conventional commercial low-cost contactless equipment, unless the user uses expensive online-operation equipment estimating the speed by means of input voltage/current. Moreover, in some rotating systems/parts not directly driven by an electric motor, the online equipment cannot be used and it is not practical, and in some cases even impossible, to couple an encoder/resolver or stick some reflective strips. In this paper, an innovative nonintrusive low-cost webcam-based tachometer is proposed, developed and experimentally tested. It can be used to easily estimate and record the speed over time in, for example, electrical motors, pulleys, shafts and wind turbines.

关键词： In-field speed measurement Motor speed Noninvasive speed measurement Rotational speed Tachometer Video camera Webcam Motor load estimation

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A Dual-Stage Robust Vehicle Detection and Tracking for Real-Time Traffic Monitoring

A Dual-Stage Robust Vehicle Detection and Tracking for Real-...

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International Conference on Intelligent Transportation

作者： J. Batista P. Peixoto C. Fernandes M. Ribeiro Department of Electrical Engineering and Computers ISR-Institute of Systems and Robotics University of Coimbra Coimbra Portugal

This paper addresses the important problem of detecting and tracking vehicles in outdoor dynamic scenes as part of a real-time traffic surveillance system. The proposed solution is based on a dual-stage approach, using a pixel-level stage to extract foreground object from background scenes and a block-level stage to detect and track vehicles. The pixel-level stage combines a multi-background modelling with a dynamic thresholding, using a low-scale quasi-connected-components as a first stage for image object grouping/cleaning. The block-level performs a 8 times 8 block-region analysis defining a block energy function that is used to label the blocks belonging to different vehicles and track them over a stack of images. This approach has proven to be very helpful for occlusion reasoning. The proposed solution has the ability to overcome some of the most difficult problem that arise in outdoor scenes such as illumination variations, shadow-casts and waving movement resulting from trees and camera vibration. The performance and robustness of the proposed algorithm is shown using real highway traffic monitoring situations

关键词： Robustness Vehicle detection Monitoring Layout Vehicle dynamics Real time systems Traffic control Surveillance Object detection Pixel

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Sensor Selection for Hypothesis Testing in Wireless Sensor Networks: a Kullback-Leibler Based Approach

Sensor Selection for Hypothesis Testing in Wireless Sensor N...

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Joint 48th IEEE Conference on Decision and Control and 28th Chinese Control Conference

作者： Dragana Bajovi Bruno Sinopoli Joo Xavier Institute for Systems and Robotics (ISR) Instituto Superior Técnico (IST) Department of Electrical and Computer Engineering Carnegie Mellon University

We consider the problem of selecting a subset of p out of n sensors for the purpose of event detection,in a wireless sensor network（WSN）.Occurrence of the event of interest is modeled as a binary Gaussian hypothesis *** this case sensor selection consists of finding,among all（~n） combinations,the one maximizing the Kullback-Leibler（KL） distance between the induced p-dimensional distributions under the two *** exhaustive search is impractical if n and p are large,as the resulting optimization problem is *** propose a suboptimal approach with computational complexity of order■（np）.This consists of relaxing the 0/1 constraint on the entries of the selection matrices to let the optimization problem search over the set of Stiefel *** finding the Stiefel matrix is a nonconvex problem,we provide an algorithm that is guaranteed to produce a global optimum for p = 1,through a series of judicious problem *** case p > 1 is tackled by an incremental,greedy *** obtained Stiefel matrix is then used to determine the sensor selection matrix which best approximates its range *** simulations are used to assess near optimality of the proposed *** also show how the proposed approach performs better than exhaustive searches once an upper bound on the computation time is set.

关键词： Sensor Selection for Hypothesis Testing in Wireless Sensor Networks a Kullback-Leibler Based Approach

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Exploration of Kinematic Optimal Control on the Lie Group SO (3) *

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IFAC Proceedings Volumes 2010年第14期43卷 1302-1307页

作者： Alessandro Saccon John Hauser A. Pedro Aguiar Institute for Systems and Robotics (ISR) Instituto Superior Técnico (IST) Lisboa Dept. of Electrical Computer and Energy Engineering University of Colorado Boulder

In this paper, we investigate a generalization of the infinite time horizon linear quadratic regulator (LQR) for systems evolving on the special orthogonal group SO(3). Using Pontryagin's Maximum Principle, we derive the necessary conditions for optimality and the associated Hamiltonian equations. For a special class of weighting matrices, we show that the optimal feedback can be computed explicitly and we prove that the non differentiable value function is the viscosity solution of an appropriate Hamiltn-Jacobi-Bellman equation on SO(3). For arbitrary positive definite weighting matrices, numerical simulations allow us to explore the relationship between the optimal trajectories and weighting matrices, and in particular to highlight nontrivial non differentiability properties of the value function.

关键词： Optimal control Special orthogonal group SO(3) Rotation matrices Lie groups Pontryagin's Maximum Principle Hamilton-Jacobi-Bellman equation

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Active CMOS-MEMS conductive probes and arrays for tunneling-based atomic-level surface imaging

Active CMOS-MEMS conductive probes and arrays for tunneling-...

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International Solid-State Sensors, Actuators and Microsystems Conference

作者： Zhang, Y. Wang, J. Santhanam, S. Fedder, G.K. Department of Electrical and Computer Engineering United States Institute for Complex Engineered Systems Pittsburgh PA United States Robotics Institute Carnegie Mellon University Pittsburgh PA United States

ISBN: (纸本)9781457701573

This paper reports on development of AFM-like active CMOS-MEMS conductive probes and arrays. The active probes are aimed for scanning tunneling microscopy (STM) imaging and field-emission (FE) assisted nanostructure formation. Two kinds of STM tip approaches compatible with CMOS-MEMS process Electron-Induced Beam Deposition (EBID) and Spindt tip method are presented, and their functionality is examined. Atomic-level resolution is achieved using tips in an ultra-high vacuum (UHV) STM. The MEMS probe working in ambient STM is also demonstrated. The active probe is equipped with a transimpedance amplifier (TIA) for tip FE current measurement around a nominal value of 1 nA. © 2011 IEEE.

关键词： CMOS integrated circuits

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The window corner algorithm for planning translational paths among polyhedral subassemblies

The window corner algorithm for planning translational paths...

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1992 IEEE/RSJ International Conference on Intelligent Robots and systems, IROS 1992

作者： Krishnan, S.S. Sanderson, A.C. New York State Center for Advanced Technology in Automation and Robotics and Electrical Computer and Systems Engineering Department Rensselaer Polytechnic Institute TroyNY12180 United States

ISBN: (纸本)0780307372

In this paper, we present a complete and exact algorithm for planning a geometrically feasible path for a polyhedral subassembly (robot) translating amongst polyhedral obstacles. Our algorithm can be used to determine whether a pair of non-convex subassemblies can be separated by a sequence of fine-motions and, possibly, contact-motions, when the amount of free space tends to be severly limited. We present the three-dimensional Window Corner algorithm to plan feasible paths. The algorithm solves the FeosiblePath problem, in worst-case time O(m5) where m is the product of the number of vertices describing the robot and obstacles respectively. A Feasiblepath solution hierarchy, for assembly sequence planning, is described for incremental, straight-line and multi-step paths. The Polyhedral Cone Representation (PCR) is introduced to efficiently represent the geometrical constraints on translation and as a basis for fast collision avoidance checks. We introduce the concept of Window Corners in the PCR and this results in a finite search space. The Polyhedral Cone Obstacle Representation (PCUR), which is a constructive representation of all boundary contact configurations, transforms the problem into that of a point moving amongst a collection, O(m), of convex obstacles. In comparison, the worstcase space complexity of the C-space boundary is O(m3). Certain contact-constrained, feasible motions, which lie on surfaces without interior points can be inaccessible in a typ i d C-space representation. © 1992 institute of electrical and Electronics Engineers Inc. All rights reserved.

关键词： Robot programming

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