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. 2023 Sep:2023:10.1109/ipin57070.2023.10332483.
doi: 10.1109/ipin57070.2023.10332483. Epub 2023 Dec 6.

Step Length Is a More Reliable Measurement Than Walking Speed for Pedestrian Dead-Reckoning

Fatemeh Elyasi  1 , Roberto Manduchi  1
Affiliations

Step Length Is a More Reliable Measurement Than Walking Speed for Pedestrian Dead-Reckoning

Fatemeh Elyasi et al. Int Conf Indoor Position Indoor Navig. 2023 Sep.

Abstract

Pedestrian dead reckoning (PDR) relies on the estimation of the length of each step taken by the walker in a path from inertial data (e.g. as recorded by a smartphone). Existing algorithms either estimate step lengths directly, or predict walking speed, which can then be integrated over a step period to obtain step length. We present an analysis, using a common architecture formed by an LSTM followed by four fully connected layers, of the quality of reconstruction when predicting step length vs. walking speed. Our experiments, conducted on a data set collected by twelve participants, strongly suggest that step length can be predicted more reliably than average walking speed over each step.

Keywords: Pedestrian dead reckoning (PDR); Smartphone inertial data; Step length estimation; Walking speed prediction.

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Figures

Fig. 1.
Fig. 1.
(a) An example of trajectory reconstructed for one foot-mounted sensor (black line). Note that the ZUPT algorithm applies a correction at each detected stance phase. The circles represent heel strike times, which are used to compute individual stride lengths (shown by grey arrows). (b) Distribution of stride lengths over all participants of our data collection (pink bars), shown together with the distribution of stride lengths for the data set of [9] (green bars).
Fig. 2.
Fig. 2.
Step period vs. step length for six participants in our study. Loci of constant walking speed (0.5 m/s, 1 m/s, and 1.5 m/s) are shown by gray lines.
Fig. 3.
Fig. 3.
(a) The architecture of the network predicting step length li or walking speed vi. (b),(c): Black line: Output of the network predicting step length (b) or walking speed (c). Vertical lines: Detected heel strikes. Red segments: ground-truth values. Blue dashed segments: Average output values in a step period. Note that the participant was taking a turn in the path, resulting in significantly reduced walking speed during the second and third steps.
Fig. 4.
Fig. 4.
Examples of step length prediction, plotted against their ground-truth values.
Fig. 5.
Fig. 5.
Examples of walking speed predictions, plotted against their ground-truth values.
See this image and copyright information in PMC

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