An algorithm for surface growing from laser scan generated point clouds

In robot applications requiring interaction with a partially/unknown environment, mapping is of paramount importance. This paper presents an effective surface growing algorithm for map building based on laser scan generated point clouds. The algorithm directly converts a point cloud into a surface and normals form which sees a significant reduction in data size and is in a desirable format for planning the interaction with surfaces. It can be used in applications such as robotic cleaning, painting and welding. © 2007 Springer-Verlag Berlin Heidelberg

A robotic system for steel bridge maintenance: Research challenges and system design

This paper presents the research on and development of a robotic system for stripping paint and rust from steel bridges, with the ultimate objective of preventing human exposure to hazardous and dangerous debris (containing rust, paint particles, lead and/or asbestos), relieving human workers from labor intensive tasks and reducing costs associated with bridge maintenance. The robot system design, the key research challenges and enabling technologies and system development are discussed in detail. Research results obtained so far and discussions on some key issues are also presented

Autonomous Bioluminescent Expression of the Bacterial Luciferase Gene Cassette (lux) in a Mammalian Cell Line

The bacterial luciferase (lux) gene cassette consists of five genes (luxCDABE) whose protein products synergistically generate bioluminescent light signals exclusive of supplementary substrate additions or exogenous manipulations. Historically expressible only in prokaryotes, the lux operon was re-synthesized through a process of multi-bicistronic, codon-optimization to demonstrate for the first time self-directed bioluminescence emission in a mammalian HEK293 cell line in vitro and in vivo.Autonomous in vitro light production was shown to be 12-fold greater than the observable background associated with untransfected control cells. The availability of reduced riboflavin phosphate (FMNH(2)) was identified as the limiting bioluminescence substrate in the mammalian cell environment even after the addition of a constitutively expressed flavin reductase gene (frp) from Vibrio harveyi. FMNH(2) supplementation led to a 151-fold increase in bioluminescence in cells expressing mammalian codon-optimized luxCDE and frp genes. When injected subcutaneously into nude mice, in vivo optical imaging permitted near instantaneous light detection that persisted independently for the 60 min length of the assay with negligible background.The speed, longevity, and self-sufficiency of lux expression in the mammalian cellular environment provides a viable and powerful alternative for real-time target visualization not currently offered by existing bioluminescent and fluorescent imaging technologies

Molecular Evolution of Phosphoprotein Phosphatases in Drosophila

Phosphoprotein phosphatases (PPP), these ancient and important regulatory enzymes are present in all eukaryotic organisms. Based on the genome sequences of 12 Drosophila species we traced the evolution of the PPP catalytic subunits and noted a substantial expansion of the gene family. We concluded that the 18–22 PPP genes of Drosophilidae were generated from a core set of 8 indispensable phosphatases that are present in most of the insects. Retropositons followed by tandem gene duplications extended the phosphatase repertoire, and sporadic gene losses contributed to the species specific variations in the PPP complement. During the course of these studies we identified 5, up till now uncharacterized phosphatase retrogenes: PpY+, PpD5+, PpD6+, Pp4+, and Pp6+ which are found only in some ancient Drosophila. We demonstrated that all of these new PPP genes exhibit a distinct male specific expression. In addition to the changes in gene numbers, the intron-exon structure and the chromosomal localization of several PPP genes was also altered during evolution. The G−C content of the coding regions decreased when a gene moved into the heterochromatic region of chromosome Y. Thus the PPP enzymes exemplify the various types of dynamic rearrangements that accompany the molecular evolution of a gene family in Drosophilidae

The Gac-Rsm and SadB Signal Transduction Pathways Converge on AlgU to Downregulate Motility in Pseudomonas fluorescens

Flagella mediated motility in Pseudomonas fluorescens F113 is tightly regulated. We have previously shown that motility is repressed by the GacA/GacS system and by SadB through downregulation of the fleQ gene, encoding the master regulator of the synthesis of flagellar components, including the flagellin FliC. Here we show that both regulatory pathways converge in the regulation of transcription and possibly translation of the algU gene, which encodes a sigma factor. AlgU is required for multiple functions, including the expression of the amrZ gene which encodes a transcriptional repressor of fleQ. Gac regulation of algU occurs during exponential growth and is exerted through the RNA binding proteins RsmA and RsmE but not RsmI. RNA immunoprecipitation assays have shown that the RsmA protein binds to a polycistronic mRNA encoding algU, mucA, mucB and mucD, resulting in lower levels of algU. We propose a model for repression of the synthesis of the flagellar apparatus linking extracellular and intracellular signalling with the levels of AlgU and a new physiological role for the Gac system in the downregulation of flagella biosynthesis during exponential growth

Safe and efficient autonomous exploration technique for 3D mapping of a complex bridge maintenance environment

This paper describes a technique for autonomously exploring a complex steel bridge environment using a 6DOF anthropomorphic robotic arm, instrumented with a laser range scanner. Potential knowledge ained from a 3D range scan at an end-effector position and orientation (pose) is estimated, then arm configurations which avoid obstacles and unknown areas are computed using an optimisation approach. Safe pose solutions are compared in terms of potential gain of new weighted-information and minimal joint movement. Both simulations and robotic platform results show exploration of unknown areas occurs in a consistent and timely manner - taking an average of 4.5secs to calculate the next safe valid robot arm poses. Complex environments, typical in bridge maintenance, can be explored using an anthropomorphic arm equipped with this technique

Verification Coverage for Combining Test and Proof

International audienceThe V&V practices of safety-critical industries (e.g. avionics) are currently based on either unit testing or unit proof to verify that a function satisfies its low-level requirements in order to be compliant with the highest certification levels, [26] (e.g. DO-178C level A for avionic software). In this context, the verification engineer must assess sufficient coverage of both code (structural coverage) and specification (functional coverage). However, there is no shared method for test and proof to measure structural coverage. In practice, this prevents the verification engineer from combining test and automatic proof to verify low-level requirements of a common piece of code in order to mitigate the verification cost. This paper fills this gap between test and proof by introducing a new notion of verification coverage based on mutation coverage. It subsumes functional coverage and structural coverage for both unit testing and unit proof. Consequently, it allows the verification engineer to mix test tools and automatic provers in the verification process for the sake of reducing verification cost, in the sense that the more automation is used during the verification, the less resource is spent to verify the program