Jens Wettach

Indoor Localisation of Humans, Objects, and mobile Robots with RFID Infrastructure

The need for robust indoor localisation for all types of entities has been under continuous research by the ubiquitous community. Intelligent environments have to be supported with contextual information in order to facilitate intelligent behaviour. These contextual information include the location of humans and objects within the particular environment. Intelligent environments can be living areas with home automation, smart industrial plants, sensor-equipped office areas and indoor-emergency applications. So far technical solutions are either quite expensive or lack of precision for robust usage as components in intelligent service federations. We present rather low-cost localisation systems with great scalability based on active and passive RFID technology to locate humans, mobile service robots and objects of the daily use. The trade-off between technical effort and costs on the one hand and sufficient data accuracy for the application on the other hand is discussed. A motivation of our scenario, the technical concept and solution as well as the implementation and the integration that so far have been performed will be presented. Current prototypes of the proposed system are already being tested in a project aiming on development of smart assisted living environments.

A Customizable, Multi-Host Simulation and Visualization Framework for Robot Applications

A highly flexible framework for visualization and sensor simulation in three-dimensional environments is presented. By allowing the insertion of freely programmable elements for online scene modification, a programmer can customize the framework to fulfill the exact simulation or visualization needs of an application of interest. Furthermore, the framework provides simple external interfaces so that multiple clients can be attached to it with ease. The frameworks’ capabilities are demonstrated with two complex robotic applications that require both a high quality simulation of cameras and lasers scanners and an intuitive 3D visualization.

Simulating vehicle kinematics with SimVis3D and Newton

This paper discusses the simulation of vehicle kinematics with SimVis3D and the Newton Game Dynamics Engine. As running example a Pioneer1 like robot is used. First its differential drive is simulated manually, without physical effects. Then the dynamics engine is applied to simulate this drive mechanism based on rolling friction between wheels and ground. Comparing the effort of application code for both approaches shows the benefit of delegating the calculation of rigid body motions. This fact is further stressed by simulating a trailer as a passive vehicle without any code extensions. Finally, a standard vehicle kinematic system consisting of Ackermann steering and rear wheel drive is realized2. The paper concludes with an application of this model for simulating the drive system of a bucket excavator as real world scenario.

Dynamic Speech Interaction for Robotic Agents

Research in mobile service robotics aims on development of intuitive speech interfaces for human-robot interaction. We see a service robot as a part of an intelligent environment and want to step forward discussing a concept where a robot does not only offer its own features via natural speech interaction but also becomes a transactive agent featuring other services’ interfaces. The provided framework makes provisions for the dynamic registration of speech interfaces to allow a loosely-coupled flexible and scalable environment. An intelligent environment can evolve out of multimedia devices, home automation, communication, security, and emergency technology. These appliances offer typical wireless or stationary control interfaces. The number of different control paradigms and differently lay-outed control devices gives a certain border in usability. As speech interfaces offer a more natural way to interact intuitively with technology we propose to centralize a general speech engine on a robotic unit. This has two reasons: The acceptance to talk to a mobile unit is estimated to be higher rather than to talk to an ambient system where no communication partner is visible. Additionally the devices or functionalities to be controlled in most cases do not provide a speech interface but offer only proprietary access.

3D Reconstruction for Exploration of Indoor Environments

Autonomous exploration of arbitrary indoor environments with a mobile robot depends on a reliable self-localization strategy. Existing approaches that use only 2D distance information from e.g. planar laser scanners may fail in highly cluttered areas due to the lack of stable landmark detection. This paper presents an approach for extracting room and furniture primitives from a 3D point cloud by matching shape primitives to the data samples. These basic building blocks can serve as landmarks for relocalization and give hints for interesting places during environmental exploration. Input data is acquired by a tiltable 2D laser scanner in reality and a realistic virtual sensor simulation. In the paper the complete process from sensor data acquisition, data filtering, RANSAC1 based plane extraction and smoothing is described and tested in simulation and reality.

Experimental Evaluation of Some Indoor Exploration Strategies

A key capability of any indoor service robot is to explore arbitrary, unknown environments in order to record a complete and correct map in minimal time. Such a map is a prerequisite of common tasks like surveillance, transportation as well as search and rescue. In recent years a series of solutions has been proposed by the authors: a dynamic enhancement of the frontier-based approach, ground plan-based exploration and a hybrid combination of both. This paper evaluates the performance of each of these strategies within an everyday office scenario in simulation and reality and discusses their pros and cons.

Control of an Autonomous Climbing Robot

Climbing robots using suction cups as the adhesion mechanism are examined in several projects worldwide. Examples of their application are window cleaning, painting, inspection of large concrete walls or steel tanks (see for example [1,4,5,7,9). The wheel-driven or legged machines that are developed in these projects are able to move on vertical walls or overarm in normal situations, but their reliability is far from reaching 100%. For, in most cases, the reasons why the robot can move over a specific surface and why it falls down in nearly similar situations are not obvious. Seeking for an optimal climbing strategy one has to answer the following questions: How can the closed-loop control generate enough forces to hold the machine on the wall without preventing the sliding movements of the suction cups over the surface? In case of complete loss of vacuum, how long will it take to generate the needed negative pressure again (based on the characteristic of the vacuum engine)? How will a surface crack of a special size change the negative pressure of a suction cup? The specific subject here is a climbing robot for the autonomous inspection of concrete walls of bridges and dams. It is wheel-driven because of the requirements of the inspection sensor system (see [8]) and its vacuum system consists of seven chambers as a result of theoretical preliminary examinations. Besides the adhesion mechanism, also the driving and navigation system have to be developed with regard to autonomously inspecting large concrete surfaces.