Agreement between Inertia and Optical Based Motion Capture during the VU-Return-to-Play- Field-Test

Abstract

The validity of an inertial sensor-based motion capture system (IMC) has not been examined within the demands of a sports-specific field movement test. This study examined the validity of an IMC during a field test (VU®) by comparing it to an optical marker-based motion capture system (MMC). Expected accuracy and precision benchmarks were computed by comparing the outcomes of a linear and functional joint fitting model within the MMC. The kinematics from the IMC in sagittal plane demonstrated correlations (r2) between 0.76 and 0.98 with root mean square differences (RMSD) < 5°, only the knee bias was within the benchmark. In the frontal plane, r2 ranged between 0.13 and 0.80 with RMSD < 10°, while the knee and hip bias was within the benchmark. For the transversal plane, r2 ranged 0.11 to 0.93 with RMSD < 7°, while the ankle, knee and hip bias remained within the benchmark. The findings indicate that ankle kinematics are not interchangeable with MMC, that hip flexion and pelvis tilt higher in IMC than MMC, while other measures are comparable to MMC. Higher pelvis tilt/hip flexion in the IMC can be explained by a one sensor tilt estimation, while ankle kinematics demonstrated a considerable level of disagreement, which is likely due to four reasons: A one sensor estimation, sensor/marker attachment, movement artefacts of shoe sole and the ankle model used.

Comparison of Motion Analysis Systems in Tracking Upper Body Movement of Myoelectric Bypass Prosthesis Users

“…The precision of the IMU system was best in the shoulder (Figure 3), which is consistent with previous results in the literature [28,32]. The variability across subjects in the elbow DOF (Figure 2) for the IMU system was likely influenced by variations in sensor placement and movement artifacts from the sensor attachment method, which are known factors in the literature [39]. The variability across subjects in the neck and torso angles (Figures 4 and 5) appeared to be heavily task-influenced and the capture accuracy of the systems was likely affected by the varying motions used by the participants to achieve the task.…”

“…The Vicon optical marker-based system was selected as the reference system based on its popularity and usage in the literature [27,[36][37][38]44,45,48,[65][66][67][68]. The IMU-based [28][29][30][31][32][39][40][41][42][43][69][70][71] and markerless systems [13,[22][23][24][25]27,38,[44][45][46][47]72,73] were selected due to popularity in the literature and due to their differing mechanisms of motion capture. Please see Appendix B for diagrams of the sensor placements for the systems and the camera placements.…”

“…There have been several previous studies comparing motion capture systems that have focused on one-to-one comparisons of a single test system and a gold standard system [29,32,[35][36][37][38][39][40][41], studied the lower limbs [26,30,40,[42][43][44][45], or relied on mechanical testing devices to ensure the greatest replicability of the ground truth [36,[46][47][48]. For the oneto-one system comparisons, the parameters examined, motions selected, and populations tested varied greatly, rendering cross-system conclusions impractical.…”

Rehabilitation and Return to Sport Assessment after Anterior Cruciate Ligament Injury: Quantifying Joint Kinematics during Complex High-Speed Tasks through Wearable Sensors

“…The main finding of the present study was that the WIS motion capture system showed overall fair-to-excellent correlation with respect to the OMB system, and acceptable measurement errors in all the movements assessed. This finding confirmed the concurrent validity of the WIS system already underlined in previous studies [18,[28][29][30], and further extended its usability to clinical applications in the ACL rehabilitation context. For the first time, a stronger focus was put on clinically relevant biomechanical parameters used by the ACL professionals in the rehabilitation protocols after ACL injury in sport-specific, highspeed, and multidirectional movements.…”