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. 2023 Jul 25;14:4472. doi: 10.1038/s41467-023-40114-2

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© The Author(s) 2023

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

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Fig. 3 — a KiDs are vertically stacked upon each other, i.e., KiD_i where i is 1…3 for evaluating the multiple device performance. b While data capturing, all these KiDs share the same spatial attributes, allowing it more straightforward to analyze the temporal attribute. c Acceleration profiles from three KiDs show the 200 Hz motion data with a similar spatial attribute. d The temporal shifts (τ_i where i is 1…3 indicate temporal shifts in each wearable device) within KiDs provide incorrect time information; thus, they provide inaccurate time stamping. e Frequency drift among three devices KiD_i where i is 1…3 when connected to the remote system without synchronization for 1024 s. f Example of KiDs latency, when connected with three devices, due to the Bluetooth transmission for a synchronized message that affects synchronization, the mean values found to be KiD₁ = 9.5 ± 1.762 ms, KiD₂ = 23.8 ± 2.01 ms, KiD₃ = 32.5 ± 2.37 ms. g The average synchronization error in these wearables is 30 ms, i.e., the frequency drift within devices and the Bluetooth latency contribute to this indeterministic error causing inaccurate time interpolation while experimenting.