Title
Fastsw: Efficient Piecewise Linear Approximation Of Quaternion-Based Orientation Sensor Signals For Motion Capturing With Wearable Imus
Abstract
In the past decade, inertial measurement sensors have found their way into many wearable devices where they are used in a broad range of applications, including fitness tracking, step counting, navigation, activity recognition, or motion capturing. One of their key features that is widely used in motion capturing applications is their capability of estimating the orientation of the device and, thus, the orientation of the limb it is attached to. However, tracking a human's motion at reasonable sampling rates comes with the drawback that a substantial amount of data needs to be transmitted between devices or to an end point where all device data is fused into the overall body pose. The communication typically happens wirelessly, which severely drains battery capacity and limits the use time. In this paper, we introduce fastSW, a novel piecewise linear approximation technique that efficiently reduces the amount of data required to be transmitted between devices. It takes advantage of the fact that, during motion, not all limbs are being moved at the same time or at the same speed, and only those devices need to transmit data that actually are being moved or that exceed a certain approximation error threshold. Our technique is efficient in computation time and memory utilization on embedded platforms, with a maximum of 210 instructions on an ARM Cortex-M4 microcontroller. Furthermore, in contrast to similar techniques, our algorithm does not affect the device orientation estimates to deviate from a unit quaternion. In our experiments on a publicly available dataset, our technique is able to compress the data to 10% of its original size, while achieving an average angular deviation of approximately 2 degrees and a maximum angular deviation below 9 degrees.
Year
DOI
Venue
2021
10.3390/s21155180
SENSORS
Keywords
DocType
Volume
piecewise linear approximation, segmentation, motion capturing, IMU, wearable sensors, orientation, quaternion
Journal
21
Issue
ISSN
Citations 
15
1424-8220
1
PageRank 
References 
Authors
0.36
0
4
Name
Order
Citations
PageRank
Florian Grützmacher121.74
Jochen Kempfle222.15
K Van Laerhoven31083185.94
Christian Haubelt410.36