Toward Online Probabilistic Path Replanning

In this talk we present work on sensor-based motion planning in initially unknown dynamic environments. Motion detection and probabilistic motion modeling are combined with a smooth navigation function to perform on-line path planning and replanning in cluttered dynamic environments such as public exhibitions. Human behavior is unforeseeable in most situations that include human-robot interaction, e.g. service robots or robotic companions. This makes motion prediction problematic (they rarely move e.g. with constant velocity along straight lines), especially in settings which include large numbers of humans. Additionally, the robot is usually required to react swiftly rather than optimally, in other words the time required to calculate the plan becomes part of the optimality criterion. The "Probabilistic Navigation Function" (PNF) is an approach for planning in these cluttered dynamic environments. It relies on probabilistic worst-case computations of the collision risk and weighs regions based on that estimate. The PNF is intended to be used for gradient-descent control of a vehicle, where the gradient indicates the best trade-off between risk and detour. An underlying reactive collision avoidance provides the tight perception-action loop to cope with the remaining collision probability. As this is work in progress, we present the approach and describe finished components and give an outlook on remaining implementation issues. Two algorithmic building blocks have been developed and tested: On-line motion detection from a mobile platform is performed by the SLIP scan alignment method to separate static from dynamic objects (it also helps with pose estimation). The interface between motion detection and path planning is a probabilistic co-occurrence estimation measuring the risk of future collisions given environment constraints and worst-case scenarios, which unifies dynamic and static elements. The risk is translated into traversal costs for an E* path planner, which produces smooth navigation functions that can incorporate new environmental information in near real-time

Narrative Situation Assessment for Human-Robot Interaction

In this paper we address the problem of inter-preting sensory data for human-robot interaction, especially when gathered from several robots at the same time. After describing motion tracking in this context, we introduce a general framework for situation representation, and how it simplifies extraction of information suitable for complex man-machine dialogs. As a concrete implementation thereof, a narrative description of a complex scene in a public exposition is created. We regard issues of interpreting sensor data in an efficient way and discuss the effects of the number of robots on the results of the scene interpretation to show that our approach is not only scalable but also profits from a growing number of robots

Transcriptomic characterization of two major Fusarium resistance quantitative trait loci (QTLs), Fhb1 and Qfhs.ifa-5A, identifies novel candidate genes

Fusarium head blight, caused by Fusarium graminearum, is a devastating disease of wheat. We developed near-isogenic lines (NILs) differing in the two strongest known F. graminearum resistance quantitative trait loci (QTLs), Qfhs.ndsu-3BS (also known as resistance gene Fhb1) and Qfhs.ifa-5A, which are located on the short arm of chromosome 3B and on chromosome 5A, respectively. These NILs showing different levels of resistance were used to identify transcripts that are changed significantly in a QTL-specific manner in response to the pathogen and between mock-inoculated samples. After inoculation with F. graminearum spores, 16 transcripts showed a significantly different response for Fhb1 and 352 for Qfhs.ifa-5A. Notably, we identified a lipid transfer protein which is constitutively at least 50-fold more abundant in plants carrying the resistant allele of Qfhs.ifa-5A. In addition to this candidate gene associated with Qfhs.ifa-5A, we identified a uridine diphosphate (UDP)-glycosyltransferase gene, designated TaUGT12887, exhibiting a positive difference in response to the pathogen in lines harbouring both QTLs relative to lines carrying only the Qfhs.ifa-5A resistance allele, suggesting Fhb1 dependence of this transcript. Yet, this dependence was observed only in the NIL with already higher basal resistance. The complete cDNA of TaUGT12887 was reconstituted from available wheat genomic sequences, and a synthetic recoded gene was expressed in a toxin-sensitive strain of Saccharomyces cerevisiae. This gene conferred deoxynivalenol resistance, albeit much weaker than that observed with the previously characterized barley HvUGT13248

Multisensor On-the-Fly Localization: Precision and Reliability for Applications

In this paper an approach for localization using geometric features from a 360 degree laser range finder and a monocular vision system is presented. Its practicability under conditions of continuous localization during motion in real-time (referred to as on-the-fly localization) is investigated in large-scale experiments. The features are infinite horizontal lines for the laser and vertical lines for the camera. They are extracted using physically well-grounded models for all sensors and passed to a Kalman filter for fusion and position estimation. Positioning accuracy close to subcentimeter has been achieved with an environment model requiring 30 bytes per square meter. Already with a moderate number of matched features, the vision information was found to further increase this precision, particularly in the orientation. The results were obtained with a fully self-contained system where extensive tests with an overall length of more than 6.4 km and 150,000 localization cycles have been conducted. The final testbed for this localization system was the Computer 2000 event, an annual computer tradeshow in Lausanne, Switzerland, where during four days visitors could give high-level navigation commands to the robot via a web interface. This gave us the opportunity to obtain results on long-term reliability and verify the practicability of the approach under application-like conditions. Furthermore, general aspects and limitations of multisensor on-the-fly localization are discussed. Keywords: Mobile robot localization; On-the-fly localization; Position tracking; Multisensor data fusion; Kalman filterin

A Lane Detection Vision Module for Driver Assistance

A driver support system should provide assistance and security to the driver. For navigaton tasks it is neccessary to determine position of the ego vehicle relative to the road. One of the principal approaches is to detect road boundaries and lanes using a vision system in the vehicle. Within the European research project "Secure Propulsion using Advanced Redundant Control (SPARC)" different approaches of lane detection are developed to meet the needs of real traffic situations. The vision module presented here is based on several image filters that provide diverse information about the environment. A set of hypotheses about the state of the system is generated by a probabilistic particle filter. Assuming a predefined model of the road the particles are tested according to image filters to infere the best belief vehicle position. Emphasis was placed on extracting relevant information from the scene and efficient testing. In particular, a new testing module based on Canny edge filter and Hough transform increased the accuracy and robustness of estimation. Perfomance of the vision module was tested under various real-road conditions

Improving the Expressiveness of Mobile Robots

RoboX is a tour guide robot, designed to interact with visitors at Expo02, the Swiss National Exhibition. During five months, ten RoboXs will be in contact with people not trained to autonomous robots and will guide them throughout an exhibition about robotics. The work exposed here was dedicated to make RoboX lifelike and credible in implementing an expression generator. This generator uses the robot capacities in order to best express its internal state which is influenced by its sensor entries and the scenario of the guided tour. In order to validate our approach, a short experiment was set up in order to present results that include appreciations of people not used to robots

Mensch-Maschine Interaktion auf der Expo.02

The interactive mobile system RoboX is presented. Ten such robots will propose tours to visitors of the swiss national exposition during five month, seven days a week, ten hours per day. Algorithms are to find and track dynamic objects through the exposition are presented and evaluated. Thus, RoboX can initiate a conversation and propose tours to visitors, all the while reacting to their movement. [paper in german] ---- Dieser Beitrag beschreibt das interaktive mobile System RoboX. Auf der Schweizer National-ausstellung Expo.02 werden zehn solcher Roboter dem Publikum Touren durch eine Ausstellung anbieten. In diesem Beitrag werden Algorithmen zum Finden und Verfolgen von bewegten Objekten vorgestellt und getestet, um zu Besucher gezielt anzusprechen und auf ihre Bewegungen zu reagieren

Design, Implementation and Exploitation of a New Fully Autonomous Tour Guide Robot

This paper presents the genesis of a tour guide robot, which has been built from the scratch based on the experience of the Autonomous Systems Lab. The production of 11 of those machines has been realized by a spin-off of the lab: BlueBotics SA. The goal was to maximize the autonomy and interactivity of the mobile platform while ensuring high robustness, security and performance. The result is an interactive moving machine named RoboX. RoboX can operate in human environments and interacts by seeing humans, talking to and looking at them, showing icons and asking them to answer its questions. The complete design of mechanics, electronics and software is presented in the first part. Then, as extraordinary test bed, the Robotics exhibition at Expo.02 (Swiss National Exhibition) permits to establish meaningful statistics over five months (from May 15 to October 20, 2002) with up to 11 robots operating at the same time