A 0.05 m Change in Inertial Measurement Unit Placement Alters Time and Frequency Domain Metrics during Running
Inertial measurement units (IMUs) provide exciting opportunities to collect large volumes of running biomechanics data in the real world. IMU signals may, however, be affected by variation in the initial IMU placement or movement of the IMU during use. To quantify the effect that changing an IMU’s l...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2024-01-01
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| Series: | Sensors |
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| Online Access: | https://www.mdpi.com/1424-8220/24/2/656 |
| _version_ | 1827369362296668160 |
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| author | Dovin Kiernan Zachary David Katzman David A. Hawkins Blaine Andrew Christiansen |
| author_facet | Dovin Kiernan Zachary David Katzman David A. Hawkins Blaine Andrew Christiansen |
| author_sort | Dovin Kiernan |
| collection | DOAJ |
| description | Inertial measurement units (IMUs) provide exciting opportunities to collect large volumes of running biomechanics data in the real world. IMU signals may, however, be affected by variation in the initial IMU placement or movement of the IMU during use. To quantify the effect that changing an IMU’s location has on running data, a reference IMU was ‘correctly’ placed on the shank, pelvis, or sacrum of 74 participants. A second IMU was ‘misplaced’ 0.05 m away, simulating a ‘worst-case’ misplacement or movement. Participants ran over-ground while data were simultaneously recorded from the reference and misplaced IMUs. Differences were captured as root mean square errors (RMSEs) and differences in the absolute peak magnitudes and timings. RMSEs were ≤1 g and ~1 rad/s for all axes and misplacement conditions while mean differences in the peak magnitude and timing reached up to 2.45 g, 2.48 rad/s, and 9.68 ms (depending on the axis and direction of misplacement). To quantify the downstream effects of these differences, initial and terminal contact times and vertical ground reaction forces were derived from both the reference and misplaced IMU. Mean differences reached up to −10.08 ms for contact times and 95.06 N for forces. Finally, the behavior in the frequency domain revealed high coherence between the reference and misplaced IMUs (particularly at frequencies ≤~10 Hz). All differences tended to be exaggerated when data were analyzed using a wearable coordinate system instead of a segment coordinate system. Overall, these results highlight the potential errors that IMU placement and movement can introduce to running biomechanics data. |
| first_indexed | 2024-03-08T09:47:04Z |
| format | Article |
| id | doaj.art-cdcda3e2b2e0491e8d32b0df42a35ee6 |
| institution | Directory Open Access Journal |
| issn | 1424-8220 |
| language | English |
| last_indexed | 2024-03-08T09:47:04Z |
| publishDate | 2024-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Sensors |
| spelling | doaj.art-cdcda3e2b2e0491e8d32b0df42a35ee62024-01-29T14:17:48ZengMDPI AGSensors1424-82202024-01-0124265610.3390/s24020656A 0.05 m Change in Inertial Measurement Unit Placement Alters Time and Frequency Domain Metrics during RunningDovin Kiernan0Zachary David Katzman1David A. Hawkins2Blaine Andrew Christiansen3Biomedical Engineering Graduate Group, University of California Davis, Davis, CA 95616, USADepartment of Neurobiology, Physiology & Behavior, University of California Davis, Davis, CA 95616, USABiomedical Engineering Graduate Group, University of California Davis, Davis, CA 95616, USABiomedical Engineering Graduate Group, University of California Davis, Davis, CA 95616, USAInertial measurement units (IMUs) provide exciting opportunities to collect large volumes of running biomechanics data in the real world. IMU signals may, however, be affected by variation in the initial IMU placement or movement of the IMU during use. To quantify the effect that changing an IMU’s location has on running data, a reference IMU was ‘correctly’ placed on the shank, pelvis, or sacrum of 74 participants. A second IMU was ‘misplaced’ 0.05 m away, simulating a ‘worst-case’ misplacement or movement. Participants ran over-ground while data were simultaneously recorded from the reference and misplaced IMUs. Differences were captured as root mean square errors (RMSEs) and differences in the absolute peak magnitudes and timings. RMSEs were ≤1 g and ~1 rad/s for all axes and misplacement conditions while mean differences in the peak magnitude and timing reached up to 2.45 g, 2.48 rad/s, and 9.68 ms (depending on the axis and direction of misplacement). To quantify the downstream effects of these differences, initial and terminal contact times and vertical ground reaction forces were derived from both the reference and misplaced IMU. Mean differences reached up to −10.08 ms for contact times and 95.06 N for forces. Finally, the behavior in the frequency domain revealed high coherence between the reference and misplaced IMUs (particularly at frequencies ≤~10 Hz). All differences tended to be exaggerated when data were analyzed using a wearable coordinate system instead of a segment coordinate system. Overall, these results highlight the potential errors that IMU placement and movement can introduce to running biomechanics data.https://www.mdpi.com/1424-8220/24/2/656gyroscopesaccelerometersin-fieldover-groundkineticskinematics |
| spellingShingle | Dovin Kiernan Zachary David Katzman David A. Hawkins Blaine Andrew Christiansen A 0.05 m Change in Inertial Measurement Unit Placement Alters Time and Frequency Domain Metrics during Running Sensors gyroscopes accelerometers in-field over-ground kinetics kinematics |
| title | A 0.05 m Change in Inertial Measurement Unit Placement Alters Time and Frequency Domain Metrics during Running |
| title_full | A 0.05 m Change in Inertial Measurement Unit Placement Alters Time and Frequency Domain Metrics during Running |
| title_fullStr | A 0.05 m Change in Inertial Measurement Unit Placement Alters Time and Frequency Domain Metrics during Running |
| title_full_unstemmed | A 0.05 m Change in Inertial Measurement Unit Placement Alters Time and Frequency Domain Metrics during Running |
| title_short | A 0.05 m Change in Inertial Measurement Unit Placement Alters Time and Frequency Domain Metrics during Running |
| title_sort | 0 05 m change in inertial measurement unit placement alters time and frequency domain metrics during running |
| topic | gyroscopes accelerometers in-field over-ground kinetics kinematics |
| url | https://www.mdpi.com/1424-8220/24/2/656 |
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