This paper presents a detailed characterization of the Hokuyo URG-04LX 2D laser range finder. While the sensor specifications only provide a rough estimation of the sensor accuracy, the present work analyzes issues such as time drift effects and dependencies on distance, target properties (color, brightness and material) as well as incidence angle. Since the sensor is intended to be used for measurements of a tubelike environment on an inspection robot, the characterization is extended by investigating the influence of the sensor orientation and dependency on lighting conditions. The sensor characteristics are compared to those of the Sick LMS 200 which is commonly used in robotic applications when size and weight are not critical constraints. The results show that the sensor accuracy is strongly depending on the target properties (color, brightness, material) and that it is consequently difficult to establish a calibration model. The paper also identifies cases for which the sensor returns faulty measurements, mainly when the surface has low reflectivity (dark surfaces, foam) or for high incidence angles on shiny surfaces. On the other hand, the repeatability of the sensor seems to be competitive with the LMS 200.

In this paper, we present the mechanical design of a compact magnetic wheeled robot - with the goal to do inspection and vibration measurements in the housings of large generators and similar environments in power plants. After a detailed analysis of the specifications in this application, we present a new vehicle structure that allows for passing sharp concave corners - even with low friction coefficient between wheels and surface - and without using an additional active DOF. The advantages of this structure and the core parameters for its optimization are described in a quasi-static 2D calculation model. A prototype was implemented and successfully tested both in laboratory and real environments. The paper concludes pointing out the future improvements for a final industrial version.

We report the faithful reproduction of the self-organized aggregation behavior of the German cockroach Blattella germanica with a group of robots. We describe the implementation of the biological model provided by Jeanson et al. in Alice robots, and we compare the behaviors of the cockroaches and the robots using the same experimental and analytical methodology. We show that the aggregation behavior of the German cockroach was successfully transferred to the Alice robot despite strong differences between robots and animals at the perceptual, actuatorial, and computational levels. This article highlights some of the major constraints one may encounter during such a work and proposes general principles to ensure that the behavioral model is accurately transferred to the artificial agents.

This paper presents the design and preliminary control of an indoor coaxial helicopter "CoaX" based on a concept of hybrid active and passive control. The robot is capable of passive roll and pitch stabilization against small disturbances while actively stabilizing the yaw and the altitude. We achieve omnidirectional horizontal motion by shifting the center of gravity. The structure is made out of lightweight polyurethane and carbon fiber. Preliminary tests show that "CoaX" is able to hover for short moments and the lateral control is effective

This paper presents the latest developments around our mobile microrobot Alice. This small robot is the starting point driving and enabling enhancements in locomotion, energy, communication, perception and control. A set of new features and new HW modules is described. The robot itself is /spl sim/2/spl times/2/spl times/2 cm/sup 3/ and is able to move, sense, receive remote commands and locally communicate with neighbor robots. Extension modules implement a long range sensor, radio communication, a linear camera and an energy pack. The current projects in biomimetic, collective and evolutionary robotics using this set of tools are also shortly explained.

In group-living animals, aggregation favours interactions as well as information exchanges between individuals, and allows thus the emergence of complex collective behaviors. In previous works, a model of a self-enhanced aggregation was deduced from experiments with the cockroach Blattella germanica. In this work, this model was implemented in micro-robots Alice and successfully reproduced the aggregation dynamics observed in a group of cockroaches. We showed that this aggregation process, based on a small set of simple behavioral rules and interactions among individuals, can be used by the group of robots to select collectively an aggregation site among two identical or different shelters. Moreover, we showed that the aggregation mechanism allows the robots as a group to "estimate" the size of each shelter during the collective decision-making process, a capacity which is not explicitly coded at the individual level but that simply emerges from the aggregation behaviour.

This paper presents general ideas on design and implementation of robots to be used together with groups of animals. This work is part of the European project LEURRE aiming to study, model and control mixed societies of animals and robots. After a short presentation of the general project, the implications on the special requirements are discussed. The design process of the robot are described leading to the implementation of the autonomous mini robot called InsBot. This is very compact (19/spl times/30/spl times/41 mm/sup 3/), has many sensors (12 IR proximity, linear camera and temperature) and is able to interact with gregarious cockroaches.

We present an overview of the prototype family of Alice miniature mobile robots and the improvements achieved so far. Applications are often the final objective but also an incentive to correct and enhance the robot abilities. The research carried out with Alice and various real-world applications, which exceed the robot's use as a research prototype, is presented. They include local and global localization, map building, control strategies for semi-autonomous operation via Internet and Matlab, its use for robot soccer tournaments and as a research platform for studies of collective behaviors.