The Experts below are selected from a list of 189930 Experts worldwide ranked by ideXlab platform

Min Tan - One of the best experts on this subject based on the ideXlab platform.

Soon-jo Chung - One of the best experts on this subject based on the ideXlab platform.

  • Neural-Swarm: Decentralized Close-Proximity Multirotor Control Using Learned Interactions
    arXiv: Robotics, 2020
    Co-Authors: Guanya Shi, Wolfgang Hönig, Yisong Yue, Soon-jo Chung
    Abstract:

    In this paper, we present Neural-Swarm, a nonlinear decentralized stable controller for Close-Proximity flight of multirotor swarms. Close-Proximity control is challenging due to the complex aerodynamic interaction effects between multirotors, such as downwash from higher vehicles to lower ones. Conventional methods often fail to properly capture these interaction effects, resulting in controllers that must maintain large safety distances between vehicles, and thus are not capable of Close-Proximity flight. Our approach combines a nominal dynamics model with a regularized permutation-invariant Deep Neural Network (DNN) that accurately learns the high-order multi-vehicle interactions. We design a stable nonlinear tracking controller using the learned model. Experimental results demonstrate that the proposed controller significantly outperforms a baseline nonlinear tracking controller with up to four times smaller worst-case height tracking errors. We also empirically demonstrate the ability of our learned model to generalize to larger swarm sizes.

  • ICRA - Neural-Swarm: Decentralized Close-Proximity Multirotor Control Using Learned Interactions
    2020 IEEE International Conference on Robotics and Automation (ICRA), 2020
    Co-Authors: Guanya Shi, Wolfgang Hönig, Yisong Yue, Soon-jo Chung
    Abstract:

    In this paper, we present Neural-Swarm, a nonlinear decentralized stable controller for Close-Proximity flight of multirotor swarms. Close-Proximity control is challenging due to the complex aerodynamic interaction effects between multirotors, such as downwash from higher vehicles to lower ones. Conventional methods often fail to properly capture these interaction effects, resulting in controllers that must maintain large safety distances between vehicles, and thus are not capable of Close-Proximity flight. Our approach combines a nominal dynamics model with a regularized permutation-invariant Deep Neural Network (DNN) that accurately learns the high-order multi-vehicle interactions. We design a stable nonlinear tracking controller using the learned model. Experimental results demonstrate that the proposed controller significantly outperforms a baseline nonlinear tracking controller with up to four times smaller worst-case height tracking errors. We also empirically demonstrate the ability of our learned model to generalize to larger swarm sizes.

Adam Eyre-walker - One of the best experts on this subject based on the ideXlab platform.

  • The Close Proximity ofEscherichia coli genes: Consequences for stop codon and synonymous codon use
    Journal of Molecular Evolution, 1996
    Co-Authors: Adam Eyre-walker
    Abstract:

    It is shown that synonymous codon usage is less biased in favor of those codons preferred by highly expressed genes at the end of Escherichia coli genes than in the middle. This appears to be due to the Close Proximity of many E. coli genes. It is shown that a substantial number of genes overlap either the Shine-Dalgarno sequence or the coding sequence of the next gene on the chromosome and that the codons that overlap have lower synonymous codon bias than those which do not. It is also shown that there is an increase in the frequency of A-ending codons, and a decrease in the frequency of G-ending codons at the end of E. coli genes that lie Close to another gene. It is suggested that these trends in composition could be associated with selection against the formation of mRNA secondary structure near the start of the next gene on the chromosome. Stop codon use is also affected by the Close Proximity of genes; many genes are forced to use TGA and TAG stop codons because they terminate either within the Shine-Dalgarno or coding sequence of the next gene on the chromosome. The implications these results have for the evolution of synonymous codon use are discussed.

  • The Close Proximity of Escherichia coli Genes: Consequences for Stop Codon and Synonymous Codon Use
    Journal of Molecular Evolution, 1996
    Co-Authors: Adam Eyre-walker
    Abstract:

    It is shown that synonymous codon usage is less biased in favor of those codons preferred by highly expressed genes at the end of Escherichia coli genes than in the middle. This appears to be due to the Close Proximity of many E. coli genes. It is shown that a substantial number of genes overlap either the Shine-Dalgarno sequence or the coding sequence of the next gene on the chromosome and that the codons that overlap have lower synonymous codon bias than those which do not. It is also shown that there is an increase in the frequency of A-ending codons, and a decrease in the frequency of G-ending codons at the end of E. coli genes that lie Close to another gene. It is suggested that these trends in composition could be associated with selection against the formation of mRNA secondary structure near the start of the next gene on the chromosome. Stop codon use is also affected by the Close Proximity of genes; many genes are forced to use TGA and TAG stop codons because they terminate either within the Shine-Dalgarno or coding sequence of the next gene on the chromosome. The implications these results have for the evolution of synonymous codon use are discussed.

Jiang Bian - One of the best experts on this subject based on the ideXlab platform.

Gareth Walker - One of the best experts on this subject based on the ideXlab platform.

  • Close Proximity of turn-continuation to possible turn-completion in conversation
    Speech Communication, 2018
    Co-Authors: Gareth Walker
    Abstract:

    Abstract Speakers in conversation are in the first instance allocated the space in which to produce a single unit of talk which could figure as a complete turn. One way speakers can continue talk beyond a point of possible turn-completion is by producing a continuation in maximally Close Proximity to the point of possible turn-completion. This article extends our understanding of how speakers do this, and to what interactional effect. Several phonetic features characterising Close-Proximity continuations are described. These include continuation of voicing, articulatory anticipation and other phonetic features. It is argued that Close-Proximity continuation helps ensure speakers get to continue their turn past a point of possible turn-completion. This argument is supported by Close inspection of the talk leading up to the point of possible turn-completion, the start of the continuation, and the responses of co-participants – especially with regard to whether the point of possible turn-completion engenders incoming talk or not. The method combines analysis of phonetic and sequential details of 240 points of possible turn-completion in audio recordings of unscripted American English telephone calls.