Intercepting a Target with Sensor Swarms

The article of record as published may be located at http://dx.doi.org/10.1109/HICSS.2013.281This paper introduces a new coordination method to intercept a mobile target in urban areas with a team of sensor platforms. The task is to intercept the target before it leaves the area. The approach combines algorithmic concepts from ant colony and particle swarm optimization in order to bias the search and to spread the team in the search area. The algorithms introduced are tested in simulation experiments on grids. The success probabilities measured are relatively high for most parameter combinations, and the target is intercepted in roughly half the simulation time on average. Furthermore, the experiments reveal robust behavior with regard to the parameter setting

Mobile robotic network deployment for intruder detection and tracking

This thesis investigates the problem of intruder detection and tracking using mobile robotic networks. In the first part of the thesis, we consider the problem of seeking an electromagnetic source using a team of robots that measure the local intensity of the emitted signal. We propose a planner for a team of robots based on Particle Swarm Optimization (PSO) which is a population based stochastic optimization technique. An equivalence is established between particles generated in the traditional PSO technique, and the mobile agents in the swarm. Since the positions of the robots are updated using the PSO algorithm, modifications are required to implement the PSO algorithm on real robots to incorporate collision avoidance strategies. The modifications necessary to implement PSO on mobile robots, and strategies to adapt to real environments are presented in this thesis. Our results are also validated on an experimental testbed. In the second part, we present a game theoretic framework for visibility-based target tracking in multi-robot teams. A team of observers (pursuers) and a team of targets (evaders) are present in an environment with obstacles. The objective of the team of observers is to track the team of targets for the maximum possible time. While the objective of the team of targets is to escape (break line-of-sight) in the minimum time. We decompose the problem into two layers. At the upper level, each pursuer is allocated to an evader through a minimum cost allocation strategy based on the risk of each evader, thereby, decomposing the agents into multiple single pursuer-single evader pairs. Two decentralized allocation strategies are proposed and implemented in this thesis. At the lower level, each pursuer computes its strategy based on the results of the single pursuer-single evader target-tracking problem. We initially address this problem in an environment containing a semi-infinite obstacle with one corner. The pursuer\u27s optimal tracking strategy is obtained regardless of the evader\u27s strategy using techniques from optimal control theory and differential games. Next, we extend the result to an environment containing multiple polygonal obstacles. We construct a pursuit field to provide a guiding vector for the pursuer which is a weighted sum of several component vectors. The performance of different combinations of component vectors is investigated. Finally, we extend our work to address the case when the obstacles are not polygonal, and the observers have constraints in motion

A Methodology to Evolve Cooperation in Pursuit Domain using Genetic Network Programming

The design of strategies to devise teamwork and cooperation among agents is a central research issue in the field of multi-agent systems (MAS). The complexity of the cooperative strategy design can rise rapidly with increasing number of agents and their behavioral sophistication. The field of cooperative multi-agent learning promises solutions to such problems by attempting to discover agent behaviors as well as suggesting new approaches by applying machine learning techniques. Due to the difficulty in specifying a priori for an effective algorithm for multiple interacting agents, and the inherent adaptability of artificially evolved agents, recently, the use of evolutionary computation as a machining learning technique and a design process has received much attention. In this thesis, we design a methodology using an evolutionary computation technique called Genetic Network Programming (GNP) to automatically evolve teamwork and cooperation among agents in the pursuit domain. Simulation results show that our proposed methodology was effective in evolving teamwork and cooperation among agents. Compared with Genetic Programming approaches, its performance is significantly superior, its computation cost is less and the learning speed is faster. We also provide some analytical results of the proposed approach

Optimization approaches for robot trajectory planning

[EN] The development of optimal trajectory planning algorithms for autonomous robots is a key issue in order to efficiently perform the robot tasks. This problem is hampered by the complex environment regarding the kinematics and dynamics of robots with several arms and/or degrees of freedom (dof), the design of collision-free trajectories and the physical limitations of the robots. This paper presents a review about the existing robot motion planning techniques and discusses their pros and cons regarding completeness, optimality, efficiency, accuracy, smoothness, stability, safety and scalability.Llopis-Albert, C.; Rubio, F.; Valero, F. (2018). Optimization approaches for robot trajectory planning. Multidisciplinary Journal for Education, Social and Technological Sciences. 5(1):1-16. doi:10.4995/muse.2018.9867SWORD1165

Online adaptation in Boolean network robots

Questa tesi si concentra su molteplici processi di adattamento online utilizzati su un robot autonomo, che è controllato da una rete booleana; l’obiettivo è adattare il suo comportamento ad un ambiente e ad un compito specifici. I risultati mostrano che il robot può adattarsi per navigare l’ambiente ed evitare le collisioni, seguendo inoltre un altro robot in movimento; riesce anche a generalizzare, quando posizionato in un’arena diversa rispetto a quella usata in allenamento. Con due dei processi di adattamento testati, il robot può esprimere più fenotipi (comportamenti) dallo stesso genotipo (nodi e connessioni della rete booleana), ottenendo così la plasticità fenotipica. Ciò si ottiene modificando l’accoppiamento tra i sensori o gli attuatori del robot con la rete

Robot Planning in Adversarial Environments Using Tree Search Techniques

One of the main advantages of robots is that they can be used in environments that are dangerous for humans. Robots can not only be used for tasks in known and safe areas but also in environments that may have adversaries. When planning the robot's actions in such scenarios, we have to consider the outcomes of a robot's actions based on the actions taken by the adversary, as well as the information available to the robot and the adversary. The goal of this dissertation is to design planning strategies that improve the robot's performance in adversarial environments. Specifically, we study how the availability of information affects the planning process and the outcome. We also study how to improve the computational efficiency by exploiting the structural properties of the underlying setting. We adopt a game-theoretic formulation and study two scenarios: adversarial active target tracking and reconnaissance in environments with adversaries. A conservative approach is to plan the robot's action assuming a worst-case adversary with complete knowledge of the robot's state and objective. We start with such a "symmetric" information game for the adversarial target tracking scenario with noisy sensing. By using the properties of the Kalman filter, we design a pruning strategy to improve the efficiency of a tree search algorithm. We investigate the performance limits of the asymmetric version where the adversary can inject false sensing data. We then study a reconnaissance scenario where the robot and the adversary have symmetric information. We design an algorithm that allows a robot to scan more area while avoiding being detected by the adversary. The symmetric adversarial model may yield too conservative plans when the adversary may not have the same information as the robot. Furthermore, the information available to the adversary may change during execution. We then investigate the dynamic version of this asymmetric information game and show how much the robot can exploit the asymmetry in information using tree search techniques. Specifically, we study scenarios where the information available to the adversary changes during execution. We devise a new algorithm for this asymmetric information game with theoretical performance guarantees and evaluate those approaches through experiments. We use qualitative examples to show how the new algorithm can outperform symmetric minimax and use quantitative experiments to show how much the improvement is