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Advanced Mobile Robots, 1997. Proceedings., Second EUROMICRO workshop on

Date 22-24 Oct. 1997

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  • Proceedings Second EUROMICRO Workshop on Advanced Mobile Robots

    Publication Year: 1997
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    Freely Available from IEEE
  • Author index

    Publication Year: 1997 , Page(s): 175
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    Freely Available from IEEE
  • Towards sophisticated mobile robot sonar sensing using pseudo-random sequences

    Publication Year: 1997 , Page(s): 120 - 125
    Cited by:  Papers (1)
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    Conventional time-of-flight sonar sensing is widely used within the autonomous mobile robot research community. One of its most severe problems is known as crosstalk. This paper presents the experimental results of a new approach which allows the robot to operate a set of sonar sensors simultaneously with no frequent misreading caused by crosstalk or external ultrasound sources. This is achieved by carefully designing the emitted bursts, i.e. by using appropriate pseudo-random sequences together with the pulse compression technique well known from radar applications View full abstract»

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  • Active acceleration compensation using a Stewart-platform on a mobile robot

    Publication Year: 1997 , Page(s): 59 - 64
    Cited by:  Papers (12)
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    If an object is transported on a mobile platform, all accelerations of the mobile platform affect the object. This is of course undesirable, since accelerations can move or even damage the object. Stewart-platforms are mostly used for simulation, where the platform generates accelerations that increase the simulation's quality. Vice versa, it's possible to use a Stewart-platform mounted on a mobile platform to compensate the unwanted accelerations by generating a tilt. The necessary movement of the platform is calculated by a washout-filter. Applications of this combination include the transport of liquids in open boxes and medical transports, where the patients must not be affected by any acceleration View full abstract»

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  • Non-supervised chromatic illuminant: corrector for autonomous robots

    Publication Year: 1997 , Page(s): 126 - 132
    Cited by:  Papers (1)
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    One of the well-known problems in colour image interpretation is the colour-constancy problem. Autonomous robots that use colour information to select objects or landmarks can be deceived in presence of heavy coloured illuminants. Classic chromatic filtering presupposes detailed information about light source characteristics, but this is not always possible. The presence of emergency lights or different kinds of light sources can heavily influence object colour. Retinex theory, by Land and McCann (1971), can resolve these problems. This theory gives color perception on a color space based on three brightness computed as relative reflectance along multiple exploration paths of the perceived scene. This paper considers the application of this theory in order to allow automatic colour detection in autonomous robots. The algorithm has been tested on simple coloured scenes illuminated with different light sources. The results obtained are compared View full abstract»

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  • The DSP multi-frequency sonar configuration of the RAM-2 mobile robot

    Publication Year: 1997 , Page(s): 113 - 119
    Cited by:  Papers (1)
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    This paper deals with the design and development of a system for controlling a ring of sixteen sonar transducers working at two different frequencies, generated by a DSP, for the mobile robot RAM-2. Data gathering speed is increased by the simultaneous firing of all sensors since the ultrasonic sensors that work at the same frequency are separated by 45°. The software and hardware implementation of the proposed perception system are presented. The results from the calibration process and the integration in the mobile robot RAM-2 are also studied View full abstract»

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  • Multirobot motion coordination using a deliberative approach

    Publication Year: 1997 , Page(s): 96 - 103
    Cited by:  Papers (2)
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    The paper investigates the practical use of the motion plan quality and of the motion plan robustness measures coupled with a deliberative scheduling approach, for computing safe motions for multiple mobile robots. The use of any-time algorithms allows one to evaluate the opportunity of looking for alternative solution paths by generating small variations of robot motions in space and in time. By using the concept of plan robustness, we generate several alternative paths that are evaluated through various performance indices and impact factors, by some heuristic rules. These indices allow one to know how much a variation affects a given plan. Finally, we outline some recent experiments View full abstract»

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  • Robustness characteristics of POLLICINO system for autonomous robot self-localization

    Publication Year: 1997 , Page(s): 163 - 167
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    POLLICINO is a system for autonomous mobile robot self-localization along previously learned routes in a dynamic environment. The system is based on a conical device that allows an omnidirectional perception of the environment and on a learning system. Robustness tests involving occlusion and robot rotations are presented View full abstract»

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  • Implications of embodiment for robot learning

    Publication Year: 1997 , Page(s): 38 - 43
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    The work is based on that of Brooks (1986), who argued that intelligence requires a body and therefore suggested that robots be used to study principles of intelligence. We show in more detail why some of the problems in intelligent behavior like category learning are simplified if the embodiment is exploited appropriately. We will also demonstrate that embodied systems can learn in an unstructured and “unlabelled” environment. Moreover, the seemingly intractable problems of behaving and learning in the real world become manageable. We will substantiate our argument with an information theoretic analysis. The work presented in this paper is theoretically motivated. It has been derived from a number of design principles of autonomous agents. They will be briefly outlined to provide the general context in which this research is situated View full abstract»

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  • A possibilistic approach to sensor fusion in mobile robotics

    Publication Year: 1997 , Page(s): 73 - 79
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    We present a formal method, based on the logic of possibility, to fuse uncertain sensory information and to produce an estimate of the position of a mobile robot. The robot navigates in an office environment, using a topological map, with the assistance of a “slave” robot acting as a portable local landmark. Each relevant place in the map is characterized by a set of logical formulae axiomatizing both “crisp” knowledge and uncertain information from the sensors. At each time instant during navigation, the necessity degree of each place is calculated using a purely syntactical method based on sequent calculus View full abstract»

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  • Q-learning of complex behaviours on a six-legged walking machine

    Publication Year: 1997 , Page(s): 51 - 58
    Cited by:  Papers (2)
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    We present work on a six-legged walking machine that uses a hierarchical version of Q-learning (HQL) to learn both the elementary swing and stance movements of individual legs as well as the overall coordination scheme to perform forward movements. The architecture consists of a hierarchy of local controllers implemented in layers. The lowest layer consists of control modules performing elementary actions, like moving a leg up, down, left or right to achieve the elementary swing and stance motions for individual legs. The next level consists of controllers that learn to perform more complex tasks like forward movement by using the previously learned, lower level modules. On the third the highest layer in the architecture presented here the previously learned complex movements are themselves reused to achieve goals in the environment using external sensory input. The work is related to similar, although simulation-based, work by Lin (1993) on hierarchical reinforcement learning and Singh (1994) on compositional Q-learning. We report on the HQL architecture as well as on its implementation on the walking machine SIR ARTHUR. Results from experiments carried out on the real robot are reported to show the applicability of the HQL approach to real world robot problems View full abstract»

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  • Active mobile robot localization by entropy minimization

    Publication Year: 1997 , Page(s): 155 - 162
    Cited by:  Papers (37)  |  Patents (19)
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    Localization is the problem of determining the position of a mobile robot from sensor data. Most existing localization approaches are passive, i.e., they do not exploit the opportunity to control the robot's effecters during localization. This paper proposes an active localization approach. The approach provides rational criteria for (1) setting the robot's motion direction (exploration), and (2) determining the pointing direction of the sensors so as to most efficiently localize the robot. Furthermore, it is able to deal with noisy sensors and approximate world models. The appropriateness of our approach is demonstrated empirically using a mobile robot in a structured office environment View full abstract»

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  • Enhancing recognizability of robotics environments

    Publication Year: 1997 , Page(s): 88 - 95
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    We consider the problem of state recognizability in robotics environments modeled by partially observable Markov decision processes. To make the model of robot-environment interaction more reliable, in the usual state transition table, we add to the state transition probabilities an additional continuous metric via the mean and the variance of some significant sensor measurements suitable to be kept under a continuous form, such as odometric measurements. These information allow one to greatly enhance the state recognizability. Our approach is general, and can be applied to any robotics application that requires compensation of the uncertainties due to sensor errors and to the randomness of robot action effects on its environment. We have devised some possible applications to modeling the interaction between a manipulator and its world, but in this paper, only a specific application to the navigation problem for a mobile robot is illustrated to show the feasibility of our approach View full abstract»

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  • Inducing topological maps from task-oriented perception and exploratory behaviors

    Publication Year: 1997 , Page(s): 134 - 140
    Cited by:  Papers (1)
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    We describe motor and perceptual behaviors that have proven useful for indoor navigation of an autonomous mobile robot. These behaviors take advantage of the large amount of structure that characterizes many indoor, office-like environments. Based on pre-existing structural landmarks, a mobile robot has the ability to explore, map, and navigate one among several office buildings sharing similar structural features, while coping with slow environment variations and local dynamics. The mobile robot develops and maintains an internal representation of the environment in terms of a topological and qualitative map. The types of structural features suitable as navigation landmarks largely depend upon the available robot sensoriality. Adequate navigation performance is achieved by subdividing perception and navigation into a number of behaviors layered upon a multi-threaded real-time control architecture View full abstract»

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  • An architecture for autonomous agents integrating symbolic and behavioral processing

    Publication Year: 1997 , Page(s): 45 - 50
    Cited by:  Papers (2)
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    A new architecture for autonomous agents is proposed. The architecture integrates the symbolic and the behavioral processing of data coming from the robot sensors. The integration is based on the introduction of a conceptual space representation that links the subconceptual level, which is a repository of behavioral modules, with the symbolic level, in which rich symbolic descriptions of the agent environment take place View full abstract»

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  • A bee-inspired robot visual homing method

    Publication Year: 1997 , Page(s): 141 - 146
    Cited by:  Papers (3)
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    This paper presents a proposal for a visual homing algorithm inspired by the behaviours of social insects. The homing method presented is based on an affine motion model of which parameters are estimated by the best matching criteria. In the matching phase no attempts are made either to recognise objects or to extract 3D models of the scene. Hypotheses and perspectives about the use of single landmarks by bees are introduced. The tests and experimental results are presented View full abstract»

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  • Navigation and guidance of an intelligent mobile robot

    Publication Year: 1997 , Page(s): 104 - 111
    Cited by:  Papers (4)
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    This paper presents an experimental mobile robot designed to operate autonomously within both indoor and outdoor environments. A sensor-based autonomous navigation architecture for a dynamically changing environment is described. Emphasis is placed on two important issues: autonomous navigation and smooth guidance of the robot. Several trajectory models are adopted to generate continuous-curvature paths in order to cope with the nonholonomic constraint of the robot and unexpected obstacles. A smooth guidance algorithm has been used to track the planned path. Experimental results demonstrate its performance View full abstract»

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  • Mobile robot navigation using recursive motion control

    Publication Year: 1997 , Page(s): 168 - 174
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    As a mobile robot travels towards its goal, sensor input is used to modify the path of the robot to prevent collision with obstacles. In conventional programming, when an obstacle is detected by the sensors, control loops are escaped according to the requirements of the executing navigation task. Thus navigational routines have to be written in a loop form with the necessary exit conditions built in. This paper presents an alternative approach, recursive motion control. Recovery paths around obstacles are planned and executed by recursively invoking the motion control software. The approach allows multiple obstacles to be handled in a consistent manner. On completion of the obstacle avoiding sub-path(s) the level of recursion is dropped to allow resumption of the original motion View full abstract»

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  • Mobile robot localization using a selforganized visual environment representation

    Publication Year: 1997 , Page(s): 29 - 36
    Cited by:  Papers (2)
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    Due to the upcoming applications in the field of service robotics mobile robots are currently receiving increasing attention in industry and the scientific community. Applications in the area of service robotics demand a high degree of system autonomy, which robots without learning capabilities will not be able to meet. Learning is required in the context of action models and appropriate perception procedures. Both are extremely difficult to acquire especially with high bandwidth sensors (e.g. video cameras) which are needed in the envisioned unstructured worlds. Self-localization is a basic requirement on mobile robots. This paper therefore proposes a new methodology for image based self-localization using a self-organized visual representation of the environment. It allows for the seamless integration of active and passive localization View full abstract»

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  • Deciding under partial ignorance

    Publication Year: 1997 , Page(s): 66 - 72
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    We study the problem of making decisions under partial ignorance, or partially quantified uncertainty. This problem arises in many applications in robotics and AI, and it has not yet got the attention it deserves. The traditional decision rules of decision under risk and under strict uncertainty (or complete ignorance) can naturally be extended to the more general case of decision under partial ignorance. We propose partial probability theory (PPT) for representing partial ignorance, and we discuss the extension to PPT of expected utility maximization. We argue that decision analysis should not be exclusively focused on optimizing but pay more serious attention to finding satisfactory actions, and to reasoning with assumptions. The extended minimax regret decision rule appears to be an important rule for satisficing View full abstract»

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  • Spatial learning with perceptually grounded representations

    Publication Year: 1997 , Page(s): 16 - 21
    Cited by:  Papers (2)
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    The goal of this paper is to develop the foundation for a spatial navigation without objective representations. Rather than building the spatial representations on a Euclidean space, a weaker conception of space is used which has a closer connection to perception. A type of spatial representation is described that uses perceptual information directly to define regions in space. By combining such regions, it is possible to derive a number of useful spatial representations such as place-fields, paths and topological maps. Compared to other methods, the representations of the presented approach have the advantage that they are always grounded in the perceptual abilities of the robot, and thus, more likely to function correctly View full abstract»

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  • Synthesis of control units for mobile robots

    Publication Year: 1997 , Page(s): 80 - 86
    Cited by:  Papers (2)
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    To design a control unit for a mobile robot, the finite state machine (FSM) describing the behavior of such a robot should be constructed. As a rule, it is difficult to construct an optimal FSM to represent a complex behavior of the mobile robot containing several subbehaviors. We present the formal method for synthesis a control for mobile robots, including the following procedures: representation of each subbehavior as an algorithmic state machine (ASM), combining several private ASMs into one aggregated ASM, constructing a finite state machine, implementing aggregated ASM, and synthesis of FSM's logic circuit View full abstract»

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  • Extension of the ALVINN-architecture for robust visual guidance of a miniature robot

    Publication Year: 1997 , Page(s): 8 - 14
    Cited by:  Papers (1)
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    Extensions of the ALVINN architecture are introduced for a KHEPERA miniature robot to navigate visually robust in a labyrinth. The reimplementation of the ALVINN-approach demonstrates, that also in indoor-environments a complex visual robot navigation is achievable using a direct input-output-mapping with a multilayer perceptron network, which is trained by expert-cloning. With the extensions it succeeds to overcome the restrictions of the small visual field of the camera by completing the input vector with history-components, introduction of the velocity dimension and evaluation of the network's output by a dynamic neural field. This creates the prerequisites to take turns which are no longer visible in the actual image and so make use of several alternatives of actions View full abstract»

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  • Landmark matching in a varying environment

    Publication Year: 1997 , Page(s): 147 - 153
    Cited by:  Papers (1)
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    A system for landmark tracking by a template matching approach is described. Route following based on landmarks may require many models to cover all different situations, so a genetic algorithm learning technique is used to adapt modelling parameters to environmental conditions (lighting, shadows, reflexes, etc.) during the tracking. In addition, the mobile robot self-localisation is obtained by a stereo approach that uses the centres of matching in the two images to solve in a simple way the correspondence analysis in the 3D position estimation. The experimental results show that the tracking robustness is improved when the adaptive template matching is used for landmark tracking View full abstract»

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  • Visual behaviours for binocular tracking

    Publication Year: 1997 , Page(s): 2 - 7
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    This paper presents a binocular tracking system based on the integration of visual behaviours. Biologically motivated behaviours, vergence and pursuit, cooperate as parallel, complementary and highly coupled processes in the tracking system, simplifying the acquisition of perceptual information and system modeling and control. The use of a space variant image representation and low-level visual cues as feedback signals in a closed loop control architecture, allow real-time and reliable performance for each behaviour, despite the low precision of the algorithms and modeling errors. The behaviours are integrated and the overall system is implemented in a stereo head running at real-time (12.5 Hz), without any specific processing hardware. Results are presented for objects of different shapes and motions, illustrating that tracking can be robustly achieved by the cooperation of purposively designed behaviours, tuned to specific subgoals View full abstract»

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