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International Conference on distributed Computing in Sensor systems (DCOSS)

作者： Ali Marjovi Adrian Arfire Alcherio Martinoli Distributed Intelligent Systems and Algorithms Laboratory School of Architecture Civil and Environmental Engineering Ecole Polytechnique Fédérale de Lausanne (EPFL) Lausanne Switzerland

We propose three modeling methods using a mobile sensor network to generate high spatio-temporal resolution air pollution maps for urban environments. In our deployment in Lausanne (Switzerland), dedicated sensing nodes are anchored to the public buses and measure multiple air quality parameters including the Lung Deposited Surface Area (LDSA), a state of the art metric for quantifying human exposure to ultra fine particles. In this paper, our focus is on generating LDSA maps. In particular, since the sensor network coverage is spatially and temporally dynamic, we leverage models to estimate the values for the locations and times where the data are not available. We first discretize the area topologically based on the street segments in the city and we then propose the following three prediction models: i) a log-linear regression model based on nine meteorological (e.g., Temperature and precipitations) and gaseous (e.g., NO 2 and CO) explanatory variables measured at two static stations in the city, ii) a novel network-based log-linear regression model that takes into account the LDSA values of the most correlated streets and also the nine explanatory variables mentioned above, iii) a novel Probabilistic Graphical Model (PGM) in which each street segment is considered as one node of the graph, and inference on conditional joint probability distributions of the nodes results in estimating the values in the nodes of interest. More than 44 millions of geo- and time-stamped LDSA measurements (i.e., More than 14 months of real data) are used in this paper to evaluate the proposed modeling approaches in various time resolutions (hourly, daily, weekly and monthly). The results show that the three approaches bring significant improvements in R2, RMSE and FAC metrics compared to a baseline K-Nearest Neighbor method.

关键词： Atmospheric modeling Pollution measurement Atmospheric measurements Mobile communication Monitoring Air pollution Cities and towns

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Top-down vs. bottom-up model-based methodologies for distributed control: a comparative experimental study 12

Top-down vs. bottom-up model-based methodologies for distrib...

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12th International Symposium on Experimental Robotics, ISER 2010

作者： Mermoud, Grégory Upadhyay, Utkarsh Evans, William C. Martinoli, Alcherio École Polytechnique Fédérale de Lausanne School of Architecture Civil and Environmental Engineering Distributed Intelligent Systems and Algorithms Laboratory Lausanne1015 Switzerland

ISBN: (纸本)9783642285714

Model-based synthesis of distributed controllers for multi-robot systems is commonly approached in either a top-down or bottom-up fashion. In this paper, we investigate the experimental challenges of both approaches, with a special emphasis on resource-constrained miniature robots. We make our comparison through a case study in which a group of 2-cm-sized mobile robots screen the environment for undesirable features, and destroy or neutralize them. First, we solve this problem using a top-down approach that relies on a graph-based representation of the system, allowing for direct optimization using numerical techniques (e.g., linear and non-linear convex optimization) under very unrealistic assumptions (e.g., infinite number of robots, perfect localization, global communication, etc.). We show how one can relax these assumptions in the context of resource-constrained robots, and explain the resulting impact on system performance. Second, we solve the same problem using a bottom-up approach, i.e., we build up computationally efficient and accurate models at multiple abstraction levels, and use them to optimize the robots’ controller using evolutionary algorithms. Finally, we outline the differences between the top-down and bottom-up approaches, and experimentally compare their performance. © Springer-Verlag Berlin Heidelberg 2014.

关键词： Convex optimization

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distributed particle swarm optimization for limited-time adaptation with real robots

Distributed particle swarm optimization for limited-time ada...

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作者： Di Mario, Ezequiel Martinoli, Alcherio Distributed Intelligent Systems and Algorithms Laboratory School of Architecture Civil and Environmental Engineering Ecole Polytechnique F´ed´erale de Lausanne 1015 Lausanne Switzerland

Evaluative techniques offer a tremendous potential for online controller design. However, when the optimization space is large and the performance metric is noisy, the overall adaptation process becomes extremely time consuming. Distributing the adaptation process reduces the required time and increases robustness to failure of individual agents. In this paper, we analyze the role of the four algorithmic parameters that determine the total evaluation time in a distributed implementation of a Particle Swarm Optimization (PSO) algorithm. For an obstacle avoidance case study using up to eight robots, we explore in simulation the lower boundaries of these parameters and propose a set of empirical guidelines for choosing their values. We then apply these guidelines to a real robot implementation and show that it is feasible to optimize 24 control parameters per robot within 2 h, a limited amount of time determined by the robots' battery life. We also show that a hybrid simulate-and-transfer approach coupled with a noise-resistant PSO algorithm can be used to further reduce experimental time as compared to a pure real-robot implementation. © 2014 Cambridge University Press.

关键词： Multipurpose robots

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Flutter suppression of a bridge section model endowed with actively controlled flap arrays

Flutter suppression of a bridge section model endowed with a...

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IEEE/RSJ International Conference on Intelligent Robots and systems

作者： M. Boberg G. Feltrin A. Martinoli Distributed Intelligent Systems and Algorithms Laboratory Ecole Polytechnique Fédérale de Lausanne Switzerland Structural Engineering Laboratory Swiss Federal Laboratories for Materials Science and Technology Duebendorf Switzerland

In this work, we investigate active flutter control of a bridge section model equipped with arrays of flaps. We consider three simple control algorithms based on an amplitude-gain and a phase-shift for actuating the flaps and stabilizing the section model. We have leveraged a linear analytical model of the structural and aeroelastic forces during flutter in order to find efficient control parameters. The proposed solution was validated with wind tunnel experiments, where all the algorithms showed capable of suppressing flutter, and the most efficient one was using all of the flaps on the deck.

关键词： Bridges Solid modeling Aerodynamics Analytical models Wind speed Damping Mathematical model

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The role of environmental and controller complexity in the distributed optimization of multi-robot obstacle avoidance

The role of environmental and controller complexity in the d...

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IEEE International Conference on Robotics and Automation (ICRA)

作者： Ezequiel Di Mario Iñaki Navarro Alcherio Martinoli Distributed Intelligent Systems and Algorithms Laboratory School of Architecture Civil and Environmental Engineering

The ability to move in complex environments is a fundamental requirement for robots to be a part of our daily lives. Increasing the controller complexity may be a desirable choice in order to obtain an improved performance. However, these two aspects may pose a considerable challenge on the optimization of robotic controllers. In this paper, we study the trade-offs between the complexity of reactive controllers and the complexity of the environment in the optimization of multi-robot obstacle avoidance for resource-constrained platforms. The optimization is carried out in simulation using a distributed, noise-resistant implementation of Particle Swarm Optimization, and the resulting controllers are evaluated both in simulation and with real robots. We show that in a simple environment, linear controllers with only two parameters perform similarly to more complex non-linear controllers with up to twenty parameters, even though the latter ones require more evaluation time to be learned. In a more complicated environment, we show that there is an increase in performance when the controllers can differentiate between front and backwards sensors, but increasing further the number of sensors and adding non-linear activation functions provide no further benefit. In both environments, augmenting reactive control laws with simple memory capabilities causes the highest increase in performance. We also show that in the complex environment the performance measurements are noisier, the optimal parameter region is smaller, and more iterations are required for the optimization process to converge.

关键词： Optimization Complexity theory Robot sensing systems Mobile robots Wheels

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Analysis of fitness noise in particle swarm optimization: From robotic learning to benchmark functions

Analysis of fitness noise in particle swarm optimization: Fr...

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Congress on Evolutionary Computation

作者： Ezequiel Di Mario Iñaki Navarro Alcherio Martinoli Distributed Intelligent Systems and Algorithms Laboratory Ecole Polytechnique Federale de Lausanne

ISBN: (纸本)9781479914869

Population-based learning techniques have been proven to be effective in dealing with noise and are thus promising tools for the optimization of robotic controllers, which have inherently noisy performance evaluations. This article discusses how the results and guidelines derived from tests on benchmark functions can be extended to the fitness distributions encountered in robotic learning. We show that the large-amplitude noise found in robotic evaluations is disruptive to the initial phases of the learning process of PSO. Under these conditions, neither increasing the population size nor increasing the number of iterations are efficient strategies to improve the performance of the learning. We also show that PSO is more sensitive to good spurious evaluations of bad solutions than bad evaluations of good solutions, i.e., there is a non-symmetric effect of noise on the performance of the learning.

关键词： Benchmark testing Noise Standards Optimization Robot sensing systems Noise measurement

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The Effect of the Environment in the Synthesis of Robotic Controllers: A Case Study in Multi-Robot Obstacle Avoidance using distributed Particle Swarm Optimization 12

The Effect of the Environment in the Synthesis of Robotic Co...

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12th European Conference on the Synthesis and Simulation of Living systems: Advances in Artificial Life, ECAL 2013

作者： Mario, Ezequiel Di Navarro, Inaki Martinoli, Alcherio Distributed Intelligent Systems and Algorithms Laboratory School of Architecture Civil and Environmental Engineering Ecole Polytechnique Federale de Lausanne Switzerland

ISBN: (纸本)9780262317092

The ability to move in complex environments is a fundamental requirement for robots to be a part of our daily lives. While in simple environments it is usually straightforward for human designers to foresee the different conditions a robot will be exposed to, for more complex environments the human design of high-performing controllers becomes a challenging task, especially when the on-board resources of the robots are limited. In this article, we use a distributed implementation of Particle Swarm Optimization to design robotic controllers that are able to navigate around obstacles of different shape and size. We analyze how the behavior and performance of the controllers differ based on the environment where learning takes place, showing that different arenas lead to different avoidance behaviors. We also test the best controllers in environments not encountered during learning, both in simulation and with real robots, and show that no single learning environment is able to generate a behavior general and robust enough to succeed in all testing environments. © 2013 Proceedings of the 12th European Conference on the Synthesis and Simulation of Living systems: Advances in Artificial Life, ECAL 2013. All rights reserved.

关键词： Controllers

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Flexible triangular formation keeping of marine robotic vehicles using range measurements 19

Flexible triangular formation keeping of marine robotic vehi...

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19th IFAC World Congress on International Federation of Automatic Control, IFAC 2014

作者： Rego, Francisco Soares, Jorge M. Pascoal, António Aguiar, A. Pedro Jones, Colin Laboratory of Robotics and Systems in Engineering and Science Instituto Superior Técnico University of Lisbon Lisbon Portugal Department of Electrical and Computer Engineering Faculty of Engineering University of Porto Porto Portugal Institute of Mechanical Engineering School of Engineering École Polytechnique Fédérale de Lausanne Lausanne Switzerland Distributed Intelligent Systems and Algorithms Laboratory School of Architecture Civil and Environmental Engineering École Polytechnique Fédérale de Lausanne Lausanne Switzerland National Institute of Oceanography Dona Paula Goa India

ISBN: (纸本)9783902823625

This paper addresses the problem of keeping an autonomous marine vehicle in a moving triangular formation by regulating its position with respect to two leader vehicles. The follower vehicle has no prior knowledge of the path described by the leaders but has access to their heading angle and is able to measure inter-vehicle ranges. It is assumed that the distance between the leaders is constant and known. A control strategy is adopted that generates speed and heading commands so as to drive suitably defined along track and cross track errors to zero. The commands are used as input to local inner loops for yaw and speed control. The paper describes the algorithms derived for range-based control and assesses their performance in simulations using realistic models of the vehicles involved. Tests with three autonomous marine vehicles equipped with acoustic modems and ranging devices allow for the evaluation of the performance of the algorithms in a real-world situation. © IFAC.

关键词： Vehicle performance

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Automated real-time control of fluidic self-assembly of microparticles

Automated real-time control of fluidic self-assembly of micr...

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IEEE International Conference on Robotics and Automation (ICRA)

作者： Massimo Mastrangeli Felix Schill Jonas Goldowsky Helmut Knapp Juergen Brugger Alcherio Martinoli Distributed Intelligent Systems and Algorithms Laboratory (DISAL) School of Architecture Civil and Environmental Engineering École Poly-technique Fédérale de Lausanne (EPFL) Lausanne Switzerland Swiss Center for Electronics and Microtechnology (CSEM) Alpnach Switzerland Ecole Polytechnique Federale de Lausanne Lausanne VD CH

Self-assembly is a key coordination mechanism for large multi-unit systems and a powerful bottom-up technology for micro/nanofabrication. Controlled self-assembly and dynamic reconfiguration of large ensembles of microscopic particles can effectively bridge these domains to build innovative systems. In this perspective, we present SelfSys, a novel platform for the automated control of the fluidic self-assembly of microparticles. SelfSys centers around a water-filled microfluidic chamber whose agitation modes, induced by a coupled ultrasonic actuator, drive the assembly. Microparticle dynamics is imaged, tracked and analyzed in real-time by an integrated software framework, which in turn algorithmically controls the agitation modes of the microchamber. The closed control loop is fully automated and can direct the stochastic assembly of microparticle clusters of preset dimension. Control issues specific to SelfSys implementation are discussed, and its potential applications presented. The SelfSys platform embodies at microscale the automated self-assembly control paradigm we first demonstrated in an earlier platform.

关键词： Assembly Real-time systems Clustering algorithms Robot kinematics Self-assembly Acoustics

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Flexible triangular formation keeping of marine robotic vehicles using range measurements 1

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IFAC Proceedings Volumes 2014年第3期47卷 5145-5150页

作者： Francisco Rego Jorge M. Soares António Pascoal A. Pedro Aguiar Colin Jones Laboratory of Robotics and Systems in Engineering and Science Instituto Superior Técnico University of Lisbon Lisbon Portugal Department of Electrical and Computer Engineering Faculty of Engineering University of Porto Porto Portugal Institute of Mechanical Engineering School of Engineering École Polytechnique Fédérale de Lausanne Lausanne Switzerland Distributed Intelligent Systems and Algorithms Laboratory School of Architecture Civil and Environmental Engineering École Polytechnique Fédérale de Lausanne Lausanne Switzerland National Institute of Oceanography Dona Paula Goa India

关键词： Autonomous Vehicles Marine systems Control Laws Formation Control Station Keeping Triangular Formations

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