237 research outputs found

    Evolution of hybrid robotic controllers for complex tasks

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    We propose an approach to the synthesis of hierarchical control systems comprising both evolved and manually programmed control for autonomous robots. We recursively divide the goal task into sub-tasks until a solution can be evolved or until a solution can easily be programmed by hand. Hierarchical composition of behavior allows us to overcome the fundamental challenges that typically prevent evolutionary robotics from being applied to complex tasks: bootstrapping the evolutionary process, avoiding deception, and successfully transferring control evolved in simulation to real robotic hardware. We demonstrate the proposed approach by synthesizing control systems for two tasks whose complexity is beyond state of the art in evolutionary robotics. The first task is a rescue task in which all behaviors are evolved. The second task is a cleaning task in which evolved behaviors are combined with a manually programmed behavior that enables the robot to open doors in the environment. We demonstrate incremental transfer of evolved control from simulation to real robotic hardware, and we show how our approach allows for the reuse of behaviors in different tasks.info:eu-repo/semantics/acceptedVersio

    Hierarchical evolution of robotic controllers for complex tasks

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    A robótica evolucionária é uma metodologia que permite que robôs aprendam a efetuar uma tarefa através da afinação automática dos seus “cérebros” (controladores). Apesar do processo evolutivo ser das formas de aprendizagem mais radicais e abertas, a sua aplicação a tarefas de maior complexidade comportamental não é fácil. Visto que os controladores são habitualmente evoluídos através de simulação computacional, é incontornável que existam diferenças entre os sensores e atuadores reais e as suas versões simuladas. Estas diferenças impedem que os controladores evoluídos alcancem um desempenho em robôs reais equivalente ao da simulação. Nesta dissertação propomos uma abordagem para ultrapassar tanto o problema da complexidade comportamental como o problema da transferência para a realidade. Mostramos como um controlador pode ser evoluído para uma tarefa complexa através da evolução hierárquica de comportamentos. Experimentamos também combinar técnicas evolucionárias com comportamentos pré-programados. Demonstramos a nossa abordagem numa tarefa em que um robô tem que encontrar e salvar um colega. O robô começa numa sala com obstáculos e o colega está localizado num labirinto ligado à sala. Dividimos a tarefa de salvamento em diferentes sub-tarefas, evoluímos controladores para cada sub-tarefa, e combinamos os controladores resultantes através de evoluções adicionais. Testamos os controladores em simulação e comparamos o desempenho num robô real. O controlador alcançou uma taxa de sucesso superior a 90% tanto na simulação como na realidade. As contribuições principais do nosso estudo são a introdução de uma metodologia inovadora para a evolução de controladores para tarefas complexas, bem como a sua demonstração num robô real.Evolutionary robotics is a methodology that allows for robots to learn how perform a task by automatically fine-tuning their “brain” (controller). Evolution is one of the most radical and open-ended forms of learning, but it has proven difficult for tasks where complex behavior is necessary (know as the bootstrapping problem). Controllers are usually evolved through computer simulation, and differences between real sensors and actuators and their simulated implementations are unavoidable. These differences prevent evolved controllers from crossing the reality gap, that is, achieving similar performance in real robotic hardware as they do in simulation. In this dissertation, we propose an approach to overcome both the bootstrapping problem and the reality gap. We demonstrate how a controller can be evolved for a complex task through hierarchical evolution of behaviors. We further experiment with combining evolutionary techniques and preprogrammed behaviors. We demonstrate our approach in a task in which a robot has to find and rescue a teammate. The robot starts in a room with obstacles and the teammate is located in a double T-maze connected to the room. We divide the rescue task into different sub-tasks, evolve controllers for each sub-task, and then combine the resulting controllers in a bottom-up fashion through additional evolutionary runs. The controller achieved a task completion rate of more than 90% both in simulation and on real robotic hardware. The main contributions of our study are the introduction of a novel methodology for evolving controllers for complex tasks, and its demonstration on real robotic hardware

    Evolutionary strategies in swarm robotics controllers

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    Nowadays, Unmanned Vehicles (UV) are widespread around the world. Most of these vehicles require a great level of human control, and mission success is reliant on this dependency. Therefore, it is important to use machine learning techniques that will train the robotic controllers to automate the control, making the process more efficient. Evolutionary strategies may be the key to having robust and adaptive learning in robotic systems. Many studies involving UV systems and evolutionary strategies have been conducted in the last years, however, there are still research gaps that need to be addressed, such as the reality gap. The reality gap occurs when controllers trained in simulated environments fail to be transferred to real robots. This work proposes an approach for solving robotic tasks using realistic simulation and using evolutionary strategies to train controllers. The chosen setup is easily scalable for multirobot systems or swarm robots. In this thesis, the simulation architecture and setup are presented, including the drone simulation model and software. The drone model chosen for the simulations is available in the real world and widely used, such as the software and flight control unit. This relevant factor makes the transition to reality smoother and easier. Controllers using behavior trees were evolved using a developed evolutionary algorithm, and several experiments were conducted. Results demonstrated that it is possible to evolve a robotic controller in realistic simulation environments, using a simulated drone model that exists in the real world, and also the same flight control unit and operating system that is generally used in real world experiments.Atualmente os Veículos Não Tripulados (VNT) encontram-se difundidos por todo o Mundo. A maioria destes veículos requerem um elevado controlo humano, e o sucesso das missões está diretamente dependente deste fator. Assim, é importante utilizar técnicas de aprendizagem automática que irão treinar os controladores dos VNT, de modo a automatizar o controlo, tornando o processo mais eficiente. As estratégias evolutivas podem ser a chave para uma aprendizagem robusta e adaptativa em sistemas robóticos. Vários estudos têm sido realizados nos últimos anos, contudo, existem lacunas que precisam de ser abordadas, tais como o reality gap. Este facto ocorre quando os controladores treinados em ambientes simulados falham ao serem transferidos para VNT reais. Este trabalho propõe uma abordagem para a resolução de missões com VNT, utilizando um simulador realista e estratégias evolutivas para treinar controladores. A arquitetura escolhida é facilmente escalável para sistemas com múltiplos VNT. Nesta tese, é apresentada a arquitetura e configuração do ambiente de simulação, incluindo o modelo e software de simulação do VNT. O modelo de VNT escolhido para as simulações é um modelo real e amplamente utilizado, assim como o software e a unidade de controlo de voo. Este fator é relevante e torna a transição para a realidade mais suave. É desenvolvido um algoritmo evolucionário para treinar um controlador, que utiliza behavior trees, e realizados diversos testes. Os resultados demonstram que é possível evoluir um controlador em ambientes de simulação realistas, utilizando um VNT simulado mas real, assim como utilizando as mesmas unidades de controlo de voo e software que são amplamente utilizados em ambiente real

    Hierarchical evolution of robotic controllers for complex tasks

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    Abstract—In this paper, we demonstrate how an artificial neural network (ANN) based controller can be synthesized for a complex task through hierarchical evolution and composition of behaviors. We demonstrate the approach in a task in which an e-puck robot has to find and rescue a teammate. The robot starts in a room with obstacles and the teammate is located in a double T-maze connected to the room. We divide the rescue task into different sub-tasks: (i) exit the room and enter the double T-maze, (ii) solve the maze to find the teammate, and (iii) guide the teammate safely to the initial room. We evolve controllers for each sub-task, and we combine the resulting controllers in a bottom-up fashion through additional evolutionary runs. We conduct evolution offline, in simulation, and we evaluate the best performing controller on real robotic hardware. The controller achieved a task completion rate of more than 90 % both in simulation and on real robotic hardware. I

    Autonomous Vehicle Coordination with Wireless Sensor and Actuator Networks

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    A coordinated team of mobile wireless sensor and actuator nodes can bring numerous benefits for various applications in the field of cooperative surveillance, mapping unknown areas, disaster management, automated highway and space exploration. This article explores the idea of mobile nodes using vehicles on wheels, augmented with wireless, sensing, and control capabilities. One of the vehicles acts as a leader, being remotely driven by the user, the others represent the followers. Each vehicle has a low-power wireless sensor node attached, featuring a 3D accelerometer and a magnetic compass. Speed and orientation are computed in real time using inertial navigation techniques. The leader periodically transmits these measures to the followers, which implement a lightweight fuzzy logic controller for imitating the leader's movement pattern. We report in detail on all development phases, covering design, simulation, controller tuning, inertial sensor evaluation, calibration, scheduling, fixed-point computation, debugging, benchmarking, field experiments, and lessons learned

    Evolution of collective behaviors for a real swarm of aquatic surface robots

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    Swarm robotics is a promising approach for the coordination of large numbers of robots. While previous studies have shown that evolutionary robotics techniques can be applied to obtain robust and efficient self-organized behaviors for robot swarms, most studies have been conducted in simulation, and the few that have been conducted on real robots have been confined to laboratory environments. In this paper, we demonstrate for the first time a swarm robotics system with evolved control successfully operating in a real and uncontrolled environment. We evolve neural network-based controllers in simulation for canonical swarm robotics tasks, namely homing, dispersion, clustering, and monitoring. We then assess the performance of the controllers on a real swarm of up to ten aquatic surface robots. Our results show that the evolved controllers transfer successfully to real robots and achieve a performance similar to the performance obtained in simulation. We validate that the evolved controllers display key properties of swarm intelligence-based control, namely scalability, flexibility, and robustness on the real swarm. We conclude with a proof-of-concept experiment in which the swarm performs a complete environmental monitoring task by combining multiple evolved controllers.info:eu-repo/semantics/publishedVersio

    Towards adaptive multi-robot systems: self-organization and self-adaptation

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    Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.The development of complex systems ensembles that operate in uncertain environments is a major challenge. The reason for this is that system designers are not able to fully specify the system during specification and development and before it is being deployed. Natural swarm systems enjoy similar characteristics, yet, being self-adaptive and being able to self-organize, these systems show beneficial emergent behaviour. Similar concepts can be extremely helpful for artificial systems, especially when it comes to multi-robot scenarios, which require such solution in order to be applicable to highly uncertain real world application. In this article, we present a comprehensive overview over state-of-the-art solutions in emergent systems, self-organization, self-adaptation, and robotics. We discuss these approaches in the light of a framework for multi-robot systems and identify similarities, differences missing links and open gaps that have to be addressed in order to make this framework possible
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