Tag Archives: Useful For Teaching

Scientific limitations to the non-scientific idea that super-intelligence will come (for exterminating humans)

January 23, 2015 20:00 ,

Ernest Davis, Ethical guidelines for a superintelligence, Artificial Intelligence, Volume 220, March 2015, Pages 121-124, ISSN 0004-3702, DOI: 10.1016/j.artint.2014.12.003.

Nick Bostrom, in his new book SuperIntelligence, argues that the creation of an artificial intelligence with human-level intelligence will be followed fairly soon by the existence of an almost omnipotent superintelligence, with consequences that may well be disastrous for humanity. He considers that it is therefore a top priority for mankind to figure out how to imbue such a superintelligence with a sense of morality; however, he considers that this task is very difficult. I discuss a number of flaws in his analysis, particularly the viewpoint that implementing ethical behavior is an especially difficult problem in AI research.

Posted in: Artificial Intelligence , Tagged: ,

How to bypass the NP-hardness of estimating the best explanation of given data (instantiated as MAP, i.e., Maximum A Posteriori, not as maximum likelihood) in discrete Bayesian Networks, through distinction of relevant and irrelevant variables

January 23, 2015 17:15 ,

Johan Kwisthout, Most frugal explanations in Bayesian networks, Artificial Intelligence, Volume 218, January 2015, Pages 56-73, ISSN 0004-3702, DOI: 10.1016/j.artint.2014.10.001

Inferring the most probable explanation to a set of variables, given a partial observation of the remaining variables, is one of the canonical computational problems in Bayesian networks, with widespread applications in AI and beyond. This problem, known as MAP, is computationally intractable (NP-hard) and remains so even when only an approximate solution is sought. We propose a heuristic formulation of the MAP problem, denoted as Inference to the Most Frugal Explanation (MFE), based on the observation that many intermediate variables (that are neither observed nor to be explained) are irrelevant with respect to the outcome of the explanatory process. An explanation based on few samples (often even a singleton sample) from these irrelevant variables is typically almost as good as an explanation based on (the computationally costly) marginalization over these variables. We show that while MFE is computationally intractable in general (as is MAP), it can be tractably approximated under plausible situational constraints, and its inferences are fairly robust with respect to which intermediate variables are considered to be relevant.

Posted in: Artificial Intelligence , Tagged: , ,

On search as a consequence of the exploration-exploitation trade-off, and as a core element in human cognition

January 23, 2015 16:58 ,

Thomas T. Hills, Peter M. Todd, David Lazer, A. David Redish, Iain D. Couzin, the Cognitive Search Research Group, Exploration versus exploitation in space, mind, and society, Trends in Cognitive Sciences, Volume 19, Issue 1, January 2015, Pages 46-54, ISSN 1364-6613, DOI: 10.1016/j.tics.2014.10.004.

Search is a ubiquitous property of life. Although diverse domains have worked on search problems largely in isolation, recent trends across disciplines indicate that the formal properties of these problems share similar structures and, often, similar solutions. Moreover, internal search (e.g., memory search) shows similar characteristics to external search (e.g., spatial foraging), including shared neural mechanisms consistent with a common evolutionary origin across species. Search problems and their solutions also scale from individuals to societies, underlying and constraining problem solving, memory, information search, and scientific and cultural innovation. In summary, search represents a core feature of cognition, with a vast influence on its evolution and processes across contexts and requiring input from multiple domains to understand its implications and scope.

Posted in: Psycho-physiological bases of engineering , Tagged: , ,

On the way humans reduce perceptual information during decision making, falling apart from statistically optimal behavior, in order to deal with the overwhelming sensory flow

January 23, 2015 16:52 ,

Christopher Summerfield, Konstantinos Tsetsos, Do humans make good decisions?, Trends in Cognitive Sciences, Volume 19, Issue 1, January 2015, Pages 27-34, ISSN 1364-6613, DOI: 10.1016/j.tics.2014.11.005

Human performance on perceptual classification tasks approaches that of an ideal observer, but economic decisions are often inconsistent and intransitive, with preferences reversing according to the local context. We discuss the view that suboptimal choices may result from the efficient coding of decision-relevant information, a strategy that allows expected inputs to be processed with higher gain than unexpected inputs. Efficient coding leads to \u2018robust\u2019 decisions that depart from optimality but maximise the information transmitted by a limited-capacity system in a rapidly-changing world. We review recent work showing that when perceptual environments are variable or volatile, perceptual decisions exhibit the same suboptimal context-dependence as economic choices, and we propose a general computational framework that accounts for findings across the two domains.

Posted in: Psycho-physiological bases of engineering , Tagged: , ,

A new simple method for mobile robot path planning based on particles and inspired in bacteria

December 19, 2014 10:24 ,

Md. Arafat Hossain, Israt Ferdous, Autonomous robot path planning in dynamic environment using a new optimization technique inspired by bacterial foraging technique, Robotics and Autonomous Systems, Volume 64, February 2015, Pages 137-141, ISSN 0921-8890, DOI: 10.1016/j.robot.2014.07.002

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Path planning is one of the basic and interesting functions for a mobile robot. This paper explores the application of Bacterial Foraging Optimization to the problem of mobile robot navigation to determine the shortest feasible path to move from any current position to the target position in an unknown environment with moving obstacles. It develops a new algorithm based on Bacterial Foraging Optimization (BFO) technique. This algorithm finds a path towards the target and avoiding the obstacles using particles which are randomly distributed on a circle around a robot. The criterion on which it selects the best particle is the distance to the target and the Gaussian cost function of the particle. Then, a high level decision strategy is used for the selection and thus proceeds for the result. It works on local environment by using a simple robot sensor. So, it is free from having generated additional map which adds cost. Furthermore, it can be implemented without requirement to tuning algorithm and complex calculation. To simulate the algorithm, the program is written in C language and the environment is created by OpenGL. To test the efficiency of the proposed technique, results are compared with Basic Bacterial Foraging Optimization (BFO) and another well-known algorithm called Particle Swarm Optimization (PSO) to give the guarantee that the proposed method gives better and optimal path.

Posted in: Robot motion planning , Tagged: ,

Taking into account the way a path serves to avoid obstacles in order to improve the three main methods of robot path planning: graph-search, probabilistic and bug

December 19, 2014 10:17 ,

Emili Hernandez, Marc Carreras, Pere Ridao, A comparison of homotopic path planning algorithms for robotic applications , Robotics and Autonomous Systems, Volume 64, February 2015, Pages 44-58, ISSN 0921-8890, DOI: 10.1016/j.robot.2014.10.021

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This paper addresses the path planning problem for robotic applications using homotopy classes. These classes provide a topological description of how paths avoid obstacles, which is an added value to the path planning problem. Homotopy classes are generated and sorted according to a lower bound heuristic estimator using a method we developed. Then, the classes are used to constrain and guide path planning algorithms. Three different path planners are presented and compared: a graph-search algorithm called Homotopic A∗ (HA∗), a probabilistic sample-based algorithm called Homotopic RRT (HRRT), and a bug-based algorithm called Homotopic Bug (HBug). Our method has been tested in simulation and in an underwater bathymetric map to compute the trajectory of an Autonomous Underwater Vehicle (AUV). A comparison with well-known path planning algorithms has also been included. Results show that our homotopic path planners improve the quality of the solutions of their respective non-homotopic versions with similar computation time while keeping the topological constraints.

Posted in: Robot motion planning , Tagged:

A survey on topological localization and mapping

December 19, 2014 10:13 ,

Emilio Garcia-Fidalgo, Alberto Ortiz, Vision-based topological mapping and localization methods: A survey , Robotics and Autonomous Systems, Volume 64, February 2015, Pages 1-20, ISSN 0921-8890, DOI: 10.1016/j.robot.2014.11.009

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Topological maps model the environment as a graph, where nodes are distinctive places of the environment and edges indicate topological relationships between them. They represent an interesting alternative to the classic metric maps, due to their simplicity and storage needs, what has made topological mapping and localization an active research area. The different solutions that have been proposed during years have been designed around several kinds of sensors. However, in the last decades, vision approaches have emerged because of the technology improvements and the amount of useful information that a camera can provide. In this paper, we review the main solutions presented in the last fifteen years, and classify them in accordance to the kind of image descriptor employed. Advantages and disadvantages of each approach are thoroughly reviewed and discussed.

Posted in: Mobile robot SLAM , Tagged: , ,

A good summary and classification of state-of-the-art motion planning algorithms and proposal of a new one that improve the expected computational cost

December 9, 2014 17:23 ,

Rickert, M.; Sieverling, A.; Brock, O., Balancing Exploration and Exploitation in Sampling-Based Motion Planning, Robotics, IEEE Transactions on , vol.30, no.6, pp.1305,1317, Dec. 2014. DOI: 10.1109/TRO.2014.2340191

We present the exploring/exploiting tree (EET) algorithm for motion planning. The EET planner deliberately trades probabilistic completeness for computational efficiency. This tradeoff enables the EET planner to outperform state-of-the-art sampling-based planners by up to three orders of magnitude. We show that these considerable speedups apply for a variety of challenging real-world motion planning problems. The performance improvements are achieved by leveraging work space information to continuously adjust the sampling behavior of the planner. When the available information captures the planning problem’s inherent structure, the planner’s sampler becomes increasingly exploitative. When the available information is less accurate, the planner automatically compensates by increasing local configuration space exploration. We show that active balancing of exploration and exploitation based on workspace information can be a key ingredient to enabling highly efficient motion planning in practical scenarios.

Posted in: Robot motion planning , Tagged: , ,

SLAM as a least-squares optimization problem and reduction of the cost through the use of spherical covariance matrices that approximate the original, sparse ones

December 9, 2014 17:09 ,

Heng Wang, Shoudong Huang, Kasra Khosoussi, Udo Frese, Gamini Dissanayake, Bingbing Liu, Dimensionality reduction for point feature SLAM problems with spherical covariance matrices, Automatica, Volume 51, January 2015, Pages 149-157, ISSN 0005-1098. DOI: 10.1016/j.automatica.2014.10.114

The main contribution of this paper is the dimensionality reduction for multiple-step 2D point feature based Simultaneous Localization and Mapping (SLAM), which is an extension of our previous work on one-step SLAM (Wang et al., 2013). It has been proved that SLAM with multiple robot poses and a number of point feature positions as variables is equivalent to an optimization problem with only the robot orientations as variables, when the associated uncertainties can be described using spherical covariance matrices. This reduces the dimension of original problem from 3 m + 2 n to m only (where m is the number of poses and n is the number of features). The optimization problem after dimensionality reduction can be solved numerically using the unconstrained optimization algorithms. While dimensionality reduction may not provide computational saving for all nonlinear optimization problems, for some SLAM problems we can achieve benefits such as improvement on time consumption and convergence. For the special case of two-step SLAM when the orientation information from odometry is not incorporated, an algorithm that can guarantee to obtain the globally optimal solution (in the maximum likelihood sense) is derived. Simulation and experimental datasets are used to verify the equivalence between the reduced nonlinear optimization problem and the original full optimization problem, as well as the proposed new algorithm for obtaining the globally optimal solution for two-step SLAM.

Posted in: Mobile robot SLAM , Tagged: , ,

Probabilistic models of several sensors plus a method for distinguishing the different hypotheses from the posterior of a PF

December 4, 2014 19:27 ,

V. Alvarez-Santos, A. Canedo-Rodriguez, R. Iglesias, X.M. Pardo, C.V. Regueiro, M. Fernandez-Delgado, Route learning and reproduction in a tour-guide robot, Robotics and Autonomous Systems, Volume 63, Part 2, January 2015, Pages 206-213, ISSN 0921-8890. DOI: 10.1016/j.robot.2014.07.013

Traditionally, route information is introduced in tour-guide robots by experts in robotics. In the tour-guide robot that we are developing, we allow the robot to learn new routes while following an instructor. In this paper we describe the route recording process that takes place while following a human, as well as, how those routes are later reproduced.

A key element of both route recording and reproduction is a robust multi-sensorial localization algorithm that we have designed, which is able to combine various sources of information to obtain an estimate of the robot’s pose. In this work we detail how the algorithm works, and how we use it to record routes. Moreover, we describe how our robot reproduces routes, including path planning within route points, and dynamic obstacle avoidance for safe navigation. Finally, we show through several trajectories how the robot was able to learn and reproduce different routes.

Posted in: Mobile Robot Localization , Tagged: , , ,