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Connectionist reinforcement learning of robot control skills

AIP Conference Proceedings 1998年第1期437卷 364-374页

作者： Rui Araújo Urbano Nunes A. T. de Almeida Institute of Systems and Robotics (ISR) Electrical Engineering Department University of Coimbra Pólo II Pinhal de Marrocos 3030 Coimbra-Portugal

Many robot manipulator tasks are difficult to model explicitly and it is difficult to design and program automatic control algorithms for them. The development, improvement, and application of learning techniques taking advantage of sensory information would enable the acquisition of new robot skills and avoid some of the difficulties of explicit programming. In this paper we use a reinforcement learning approach for on-line generation of skills for control of robot manipulator systems. Instead of generating skills by explicit programming of a perception to action mapping they are generated by trial and error learning, guided by a performance evaluation feedback function. The resulting system may be seen as an anticipatory system that constructs an internal representation model of itself and of its environment. This enables it to identify its current situation and to generate corresponding appropriate commands to the system in order to perform the required skill. The method was applied to the problem of learning a force control skill in which the tool-tip of a robot manipulator must be moved from a free space situation, to a contact state with a compliant surface and having a constant interaction force.

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A Drowsiness and Point of Attention Monitoring System for Driver Vigilance

A Drowsiness and Point of Attention Monitoring System for Dr...

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International Conference on Intelligent Transportation

作者： Jorge Batista ISR-Institute of Systems and Robotics Department of Electrical Engineering and Computers FCTUC University of Coimbra Coimbra Portugal

This paper presents a framework that combines a robust facial features location with an elliptical face modelling to measure driver's vigilance level. The proposed solution deals with the computation of eyelid movement parameters and head (face) point of attention. The most important facial feature points are automatically detected using a statistically anthropometric face model. After observing the structural symmetry of the human face and performing some anthropometric measurements, the system is able to build a model that can be used in isolating the most important facial feature areas: mouth, eyes and eyebrows. Combination of different image processing techniques are applied within the selected regions for detecting the most important facial feature points. A model based approach is used to estimate the 3D orientation of the human face. The shape of the face is modelled as an ellipse assuming that the human face aspect ratio (ratio of the major to minor axes of the 3D face ellipse) is known. The elliptical fitting of the face at the image level is constrained by the location of the eyes which considerable increase the performance of the system. The system is fully automatic and classifies rotation in all-view direction, detects eye blinking and eye closure and recovers the principal facial features points over a wide range of human head rotations. Experimental results using real images sequences demonstrates the accuracy and robustness of the proposed solution.

关键词： Monitoring Face detection Facial features Humans Robustness Head Eyes Eyelids Performance evaluation Area measurement

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Volumetric Based Inspection

Volumetric Based Inspection

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

作者： Tarbox, G.H. Gottschlich, S.N. Gerhardt, L.A. New York State Center for Advanced Technology in Robotics and Automation Electrical Computer and Systems Engineering Department Rensselaer Polytechnic Institute TroyNY12180-3590 United States

ISBN: (纸本)0780307372

A novel approach to inspection is presented based on comparing a volumetric representation of a reference object to a volumetric representation of an actual object iteratively created from sensor data. The use of volumetric representations gives this approach a number of distinct advantages over the more traditional surface-based inspection methods. One significant advantage of volumetric inspection is that there is no need to identify geometric "features", particularly important when inspecting objects such as castings and forgings whose features are often difficult to identify. Secondly, the volumetric representation lends itself naturally to a multi-sensor environment. By this we mean that a volumetric model of the sensed object can be synthesized utilizing information from multiple sensors of varying types, accuracy, location, etc. This allows a choice of the most appropriate sensor for acquiring information about the different regions of the object. Finally, the volumetric representation allows us to carry out true three-dimensional inspection as opposed to the typical approach where renderings of the reference model are compared to two-dimensional images of the actual object. © 1992 IEEE.

关键词： Inspection

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Soft Sensors for Industrial Applications: Comparison of Variables Selection Methods and Regression Models

Soft Sensors for Industrial Applications: Comparison of Vari...

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2023 International Conference on Control, Automation and Diagnosis, ICCAD 2023

作者： Leiria, Joana Salles, Rodrigo Mendes, Jerome Sousa, Pedro University of Coimbra Institute of Systems and Robotics Department of Electrical and Computer Engineering Coimbra3030-290 Portugal Oncontrol Technologies Rua Cidade Poitiers Coimbra3000-108 Portugal

ISBN: (纸本)9798350347074

The digitalization of industrial environments has enabled the development of tools that make the production process more efficient and safer. In this sense, the Soft Sensor (SS) plays a fundamental role. Through historical data and indirect measurements, it is possible to estimate the value of important variables that are difficult to measure. This paper presents the SS development process: data collection and pre-processing, variable selection, model selection for SS implementation, model training and testing, and performance evaluation. The selection of variables was made with the help of Pearson Correlation, Mutual Information, and fastTracker algorithm techniques. For the implementation of SS have been tested several models: Multiple Linear Regression, Ridge Regression, Least Absolute Shrinkage and Selection Operator, Elastic Net, Support Vector Regression and Gaussian Mixture Models. Four datasets were used to test the development of the SS. © 2023 IEEE.

关键词： Correlation methods

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Estimating traffic intensity using profile images on rectified images

Estimating traffic intensity using profile images on rectifi...

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IEEE International Conference on Image Processing

作者： Cristina Maduro Katherine Batista Jorge Batista ISR-Institute of Systems and Robotics Department of Electrical Engineering FCT-Universidade de Coimbra Coimbra Portugal

In this paper a technique is presented to estimate the traffic intensity for each lane. This method does not require background estimation or even the identification and tracking of individual vehicles. It requires only the identification of each lane and the estimation of a bird eye view of the highway using a rectification method. To each rectified lane, an intensity profile is computed along the traffic flow direction for each frame, obtaining an image that represents the displacement as a time function. The main idea is to search for the best matching profile for different times and spaces on each lane and consequently obtain the velocity profile.

关键词： Vehicle detection Cameras Road transportation Surveillance Polynomials Space technology Robots Birds computer vision Parameter estimation

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Stability Analysis and Performance Evaluation of Delayed Bilateral Telerobotic systems over a Lossy Communication Channel

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Journal of systems Science & Complexity 2021年第1期34卷 157-179页

作者： BAKHSHI Ali ALFI Alireza TALEBI Heidar Ali SOURATGAR Amir Aboulfazl YOUSEFI Mahdi Faculty of Electrical and Robotic Engineering Shahrood University of TechnologyShahrood 36199-95161Iran Power Plants Control Systems Technology Development Plan Department of monitoring and ControlNiroo Research InstituteTehran 14665-517Iran Real-Time and Robotics system Laboratory Faculty of Electrical EngineeringAmirkabir University of TechnologyHafez AvenueTehran 15914Iran Electrical and Computer Engineering Department The University of British Columbia2385East MallVan couverBC V6T 1Z4Canada

The focus of this paper is to address a novel control technique for stability and transparency analysis of bilateral telerobotic systems in the presence of data loss and time delay in the communication channel. Different control strategies have been reported to compensate the effects of time delay in the communication channel;however, most of them result in poor performance under data loss. First, a model for data loss is proposed using a finite series representation of a set of periodic continuous *** improve the performance and data reconstruction, a holder circuits is also introduced. The passivity of the overall system is provided via the wave variable technique based on the proposed model for the data loss. The stability analysis of the system is then derived using the Lyapunov theorem under the time delay and the data loss. Finally, experimental results are given to illustrate the capability of the proposed control technique.

关键词： Lossy channel passivity stability telerobotic transparency

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Exact Rate for Convergence in Probability of Averaging Processes via Generalized Min-Cut

Exact Rate for Convergence in Probability of Averaging Proce...

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IEEE Annual Conference on Decision and Control

作者： Dragana Bajovic Joao Xavier Jose M. F. Moura Bruno Sinopoli Department of Electrical and Computer Engineering Carnegie Mellon University Institute for Systems and Robotics (ISR) Instituto Superior Tecnico (IST) Technical University of Lisbon

ISBN: (纸本)9781467320658

We study the asymptotic exponential decay rate I for the convergence in probability of products W_kW_(k-1) ...W_1 of random symmetric, stochastic matrices W_k. Albeit it is known that the probability P that the product W_kW_(k-1)...W_1 is ∈ away from its limit converges exponentially fast to zero, i.e., P ～ e~(-kI), the asymptotic rate I has not been computed before. In this paper, assuming the positive entries of W_k are bounded away from zero, we explicitly characterize the rate I and show that it is a function of the underlying graphs that support the positive (non zero) entries of W_k. In particular, the rate I is given by a certain generalization of the min-cut problem. Although this min-cut problem is in general combinatorial, we show how to exactly compute I in polynomial time for the commonly used matrix models, gossip and link failure. Further, for a class of models for which I is difficult to compute, we give easily computable bounds: I ≤ I ≤ I, where I and I differ by a constant ratio. Finally, we show the relevance of I as a system design metric with the example of optimal power allocation in consensus+innovations distributed detection.

关键词： dividing and cutting machine iodine Converge power splitting Zero Gossip

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Markerless Multi-View-based Multi-User Head Tracking System for Virtual Reality Applications

Markerless Multi-View-based Multi-User Head Tracking System ...

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IEEE International Conference on systems, Man and Cybernetics

作者： Dylan Bicho Pedro Girão João Paulo Luís Garrote Urbano J. Nunes Paulo Peixoto Department of Electrical and Computer Engineering Institute of Systems and Robotics University of Coimbra

In this paper, we propose a markerless multi-view-based multi-user head tracking system for VR/AR/MR applications. In the Virtual Reality domain, the user typically interacts with the virtual world through his movements. The point-of-view of the user's head mounted display (HMD) is based on the user's head pose. Most systems track the head of the user based on the tracking of the HMD itself and are typically constrained to a single user. Aiming to improve the user's experience in complex dynamic environments, we propose a head tracking method based on a multi-camera scenario, able to deal with the interaction of multiple users while coping with the existence of dynamic objects. The method relies on the voxelization of dense point cloud data, which is segmented to detect elements in the scene. Each element is holistically tracked along time and each detected user has his head's position tracked using a dedicated Particle Filter. The system was evaluated using an annotated ground-truth, according to several metrics, and demonstrated a mean 3D positioning error below 18 mm. Furthermore, tests with multiple users were performed that successfully validate the proposed head tracking approach. The aforementioned tests also showed that the proposed approach is computationally efficient (running time below 20 ms for 4 users).

关键词： Three-dimensional displays Head Resists Sensors Cameras Virtual reality Tracking

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Accelerometer-based control of an industrial robotic arm

Accelerometer-based control of an industrial robotic arm

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IEEE International Workshop on Robot and Human Communication (ROMAN)

作者： Pedro Neto J. Norberto Pires A. Paulo Moreira Industrial Robotics Laboratory-Mechanical Engineering Department POLO II University of Coimbra Coimbra Portugal Institute of Systems and Robotics (ISR)-Department of Electrical and Computer Engineering University of Porta Porto Portugal

Most of industrial robots are still programmed using the typical teaching process, through the use of the robot teach pendant. In this paper is proposed an accelerometer-based system to control an industrial robot using two low-cost and small 3-axis wireless accelerometers. These accelerometers are attached to the human arms, capturing its behavior (gestures and postures). An Artificial Neural Network (ANN) trained with a back-propagation algorithm was used to recognize arm gestures and postures, which then will be used as input in the control of the robot. The aim is that the robot starts the movement almost at the same time as the user starts to perform a gesture or posture (low response time). The results show that the system allows the control of an industrial robot in an intuitive way. However, the achieved recognition rate of gestures and postures (92%) should be improved in future, keeping the compromise with the system response time (160 milliseconds). Finally, the results of some tests performed with an industrial robot are presented and discussed.

关键词： Industrial control Service robots electrical equipment industry Defense industry Educational robots Robot control Control systems Accelerometers Artificial neural networks Delay

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Parameterizing Interpersonal Behaviour with Laban Movement Analysis - A Bayesian Approach -

Parameterizing Interpersonal Behaviour with Laban Movement A...

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IEEE computer Society Conference on computer Vision and Pattern Recognition Workshops

作者： Kamrad Khoshhal Roudposhti Luís Santos Hadi Aliakbarpour Jorge Dias Institute of Systems and Robotics Department of Electrical and Computer Engineering University of Coimbra

ISBN: (纸本)9781467316118

In this paper we propose a probabilistic model to parameterize human interactive behaviour from human motion. To Support the model taxonomy, we use Laban Movement Analysis (LMA), proposed by Rudolph Laban [11], to characterize human non-verbal communication. In interpersonal communication, body motion carries a lot of meaningful information, useful to analyse group dynamic behaviors in a wide range of social scenarios (e.g. behaviour analysis of human interpersonal activities and surveillance system). Taking the advantage of interpretation of social signals defined by Alex Pentland [19], and the descriptive body movement analysis proposed by Laban, we identified characteristics allowing both works to complement each other. To explore in group dynamics, we attempt to show the existent connections between Pentland’s descriptions for Interpersonal Behaviours (IBs), and LMA parameters for human body part motions. Those relations are the keys to characterize the interpersonal communication. Given the uncertainty of the phenomenon, Bayesian’s methodology is applied. The results present LMA parameters as reliable indicators for IBs, allowing us to generalize the model.

关键词： Parameterizing Interpersonal Behaviour Bayes methods Personal Communication group dynamics Human motion Probabilistic Model SURVEILLANCE systems Keys Keys Cays Movements Nonverbal Communication Analysis behavioral research Irritable Bowel Syndrome body movement

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