A four-state adaptive Hopf oscillator

Adaptive oscillators (AOs) are nonlinear oscillators with plastic states that encode information. Here, an analog implementation of a four-state adaptive oscillator, including design, fabrication, and verification through hardware measurement, is presented. The result is an oscillator that can learn...

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Bibliographic Details
Published in:PloS one 2021-03, Vol.16 (3), p.e0249131-e0249131
Main Authors: Li, XiaoFu, Shougat, Md Raf E Ul, Kennedy, Scott, Fendley, Casey, Dean, Robert N, Beal, Aubrey N, Perkins, Edmon
Format: Article
Language:English
Subjects:
Aerospace engineering
Analyzers
Biology and Life Sciences
Circuits
Computer and Information Sciences
Computer engineering
Computer programs
Data collection
Decision analysis
Drafting software
Editing
Energy harvesting
Engineering
Engineering and Technology
Field programmable gate arrays
Frequency analyzers
Funding
Gait
Information processing
Mechanical engineers
Methodology
Oscillators
Physical Sciences
Research and Analysis Methods
Reviews
Robots
Software
Visualization
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Summary:Adaptive oscillators (AOs) are nonlinear oscillators with plastic states that encode information. Here, an analog implementation of a four-state adaptive oscillator, including design, fabrication, and verification through hardware measurement, is presented. The result is an oscillator that can learn the frequency and amplitude of an external stimulus over a large range. Notably, the adaptive oscillator learns parameters of external stimuli through its ability to completely synchronize without using any pre- or post-processing methods. Previously, Hopf oscillators have been built as two-state (a regular Hopf oscillator) and three-state (a Hopf oscillator with adaptive frequency) systems via VLSI and FPGA designs. Building on these important implementations, a continuous-time, analog circuit implementation of a Hopf oscillator with adaptive frequency and amplitude is achieved. The hardware measurements and SPICE simulation show good agreement. To demonstrate some of its functionality, the circuit's response to several complex waveforms, including the response of a square wave, a sawtooth wave, strain gauge data of an impact of a nonlinear beam, and audio data of a noisy microphone recording, are reported. By learning both the frequency and amplitude, this circuit could be used to enhance applications of AOs for robotic gait, clock oscillators, analog frequency analyzers, and energy harvesting.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0249131