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“Nonlinear Feedback Control and Stability Analysis of a Proof-of-Work Blockchain”

Authors: Geir Hovland and Jan Kucera,
Affiliation: University of Agder and Bismuth Foundation
Reference: 2017, Vol 38, No 4, pp. 157-168.

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Keywords: Nonlinear, control system, blockchain, feedback, stability, disturbance rejection

Abstract: In this paper a novel feedback controller and stability analysis of a blockchain implementation is developed by using a control engineering perspective. The controller output equals the difficulty adjustment in the mining process while the feedback variable is the average block time over a certain time period. The computational power (hash rate) of the miners is considered a disturbance in the model. The developed controller is tested against a simulation model with constant disturbance, step and ramp responses as well as with a high-frequency sinusoidal disturbance. Stability and a fast response is demonstrated in all these cases with a controller which adjusts it's output at every new block. Finally the performance of the controller is implemented and demonstrated on a testnet with a constant hash rate as well as on the mainnet of a public open source blockchain project.

PDF PDF (2733 Kb)        DOI: 10.4173/mic.2017.4.1



DOI forward links to this article:
  [1] Jan Kucera and Geir Hovland (2018), doi:10.4173/mic.2018.3.1


References:
[1] Booth, N. (2017). Booth, N, Kyuupichan’s Difficulty Algorithm (D578) Explained. https://tinyurl.com/y8zxvn7g, visited on Dec. 1. .
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[3] Kucera, J. (2017). Kucera, J, Bismuth source code, release 4.2.1.9. https://github.com/hclivess/Bismuth/releases, commit hash e18a9a8e99c9985f2da637d4e7cb04367a78154a. .
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[7] Smith, S.W. (1999). Smith, S, W. The Scientist and Engineer's Guide to Digital Signal Processing. California Technical Publishing, San Diego, California, 2nd edition, 1999. .


BibTeX:
@article{MIC-2017-4-1,
  title={{Nonlinear Feedback Control and Stability Analysis of a Proof-of-Work Blockchain}},
  author={Hovland, Geir and Kucera, Jan},
  journal={Modeling, Identification and Control},
  volume={38},
  number={4},
  pages={157--168},
  year={2017},
  doi={10.4173/mic.2017.4.1},
  publisher={Norwegian Society of Automatic Control}
};

PDF  Errata: http://www.mic-journal.no/PDF/2017/MIC-2017-4-1-Errata.pdf

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