Table 3.
Mean (SD) upper arm elevation displacement across 13 participants and three material transfer rates: slow (15 cycles/min), medium (30 cycles/min), and fast (45 cycles/min) that was maintained for a period of 1 min. Displacements were measured by the optical motion capture system (OMC) and calculated using an accelerometer (Accel), first-order complementary filter (Comp-1), a second-order complementary filter (Comp-2), a modified linear Kalman filter (Accel-KF), and an embedded Kalman filter (Em-KF).
| Upper Arm Elevation Displacement | OMC | Accel | Comp-1 | Comp-2 | Accel-KF | Em-KF |
|---|---|---|---|---|---|---|
|
| ||||||
| ‘Slow’ Transfer Rate | ||||||
| RMS error (°) | -REF- | 2.3(0.4) | 1.6(0.9)* | 1.8(0.5)** | 1.1(0.6)** | 1.2(0.9)** |
| Peak error (°) | -REF- | 6.8(1.7) | 3.3(1.4)** | 4.1(1.0)** | 2.2(1.0)** | 2.4(1.6)** |
| Mean (°) | 47.4(7.7) | 46.5(7.8) | 46.9(8.2) | 46.6(7.9) | 46.7(7.8) | 46.8(7.4) |
| 10th Percentile (°) | 20.5(6.4) | 20.4(6.4) | 21.0(6.9) | 20.5(6.5) | 20.4(6.6) | 20.4(6.3) |
| 50th Percentile (°) | 46.1(8.9) | 46.2(8.7) | 45.5(9.2) | 45.9(8.8) | 45.4(8.8) | 45.5(8.5) |
| 90th Percentile (°) | 75.4(8.7) | 72.5(9.1) | 74.2(9.2) | 73.4(9.1) | 74.2(8.8) | 74.3(8.4) |
| Percentile Range (90th – 10th)(°) | 54.9(4.4) | 52.1(4.5) | 53.2(4.1) | 52.9(4.3) | 53.7(4.0) | 53.9(4.0) |
| Time in neutral posture (<20°) (%) | 12.3(13.7) | 12.0(12.9) | 11.6(13.9) | 12.2(13.4) | 12.3(13.7) | 12.1(13.2) |
| Time in extreme posture (≥45°)(%) | 50.4(7.5) | 50.6(8.3) | 49.8(8.2) | 50.2(8.1) | 49.7(7.7) | 49.9(7.2) |
| Time in extreme posture (≥60°)(%) | 35.4(12.4) | 33.4(13.7) | 34.0(13.4) | 33.8(13.4) | 34.0(13.2) | 34.7(11.8) |
| ‘Medium’ Transfer Rate | ||||||
| RMS error (°) | -REF- | 6.3(1.5) | 2.4(1.0)** | 2.4(0.6)** | 1.3(0.6)** | 1.4(1.0)** |
| Peak error (°) | -REF- | 17.5(4.6) | 5.7(4.4)** | 5.3(1.2)** | 2.7(1.1)** | 2.5(1.5)** |
| Mean (°) | 44.4(7.3) | 42.9(7.4) | 43.8(7.6) | 44.2(7.8) | 43.7(7.4) | 43.5(7.5) |
| 10th Percentile (°) | 19.0(6.8) | 20.8(6.9) | 19.8(7.0) | 20.1(7.3) | 19.1(6.9) | 18.9(6.8) |
| 50th Percentile (°) | 41.8(8.1) | 43.9(7.6) | 41.1(8.1) | 41.5(8.2) | 41.1(8.0) | 40.9(8.2) |
| 90th Percentile (°) | 73.1(9.1) | 63.3(8.6) | 71.4(9.1) | 71.8(9.4) | 71.7(9.0) | 71.5(9.2) |
| Percentile Range (90th – 10th)(°) | 54.1(5.4) | 42.5(4.7) | 51.6(5.2) | 51.7(5.0) | 52.7(5.3) | 52.7(5.2) |
| Time in neutral posture (<20) (%) | 15.4(13.4) | 11.7(11.9) | 13.9(13.6) | 13.6(13.9) | 15.2(13.6) | 15.5(13.7) |
| Time in extreme posture (≥45°)(%) | 46.3(8.5) | 46.9(12.3) | 45.4(9.0) | 45.8(9.1) | 45.5(8.7) | 45.2(8.8) |
| Time in extreme posture (≥60°)(%) | 29.8(12.0) | 21.0(15.8) | 27.7(12.9) | 28.0(13.0) | 28.0(12.9) | 27.6(13.2) |
| ‘Fast’ Transfer Rate | ||||||
| RMS error (°) | -REF- | 11.3(1.9) | 3.2(0.8)** | 2.9(1.1)** | 1.5(0.5)** | 1.2(0.8)** |
| Peak error (°) | -REF- | 28.9(5.2) | 6.5(1.8)** | 5.7(1.6)** | 3.2(1.0)** | 2.4(1.2)** |
| Mean (°) | 43.6(7.2) | 40.7(6.9) | 43.3(7.4) | 44.1(8.4) | 42.9(7.3) | 43.3(7.4) |
| 10th Percentile (°) | 18.1(5.8) | 23.0(6.4) | 19.5(6.3) | 19.4(6.9) | 18.2(6.0) | 18.5(5.9) |
| 50th Percentile (°) | 42.3(7.9) | 43.7(7.2) | 42.0(7.9) | 42.4(8.9) | 41.6(7.9) | 42.0(8.2) |
| 90th Percentile (°) | 71.1(9.1) | 54.8(7.8) | 69.2(9.2) | 71.3(10.2) | 69.8(9.2) | 70.2(9.1) |
| Percentile Range (90th – 10th)(°) | 53.0(6.2) | 31.8(4.3) | 49.7(6.1) | 51.9(6.2) | 51.6(6.1) | 51.7(5.9) |
| Time in neutral posture (<20) (%) | 16.1(11.4) | 8.0(9.6) | 12.9(12.2) | 14.2(13.3) | 15.9(11.8) | 15.5(12) |
| Time in extreme posture (≥45°)(%) | 46.3(9.1) | 41.1(20.9) | 45.7(9.7) | 46.5(10.3) | 45.4(9.3) | 45.9(9.5) |
| Time in extreme posture (≥60°)(%) | 28.1(12.8) | 8.3(10.2) | 25.5(14.3) | 27.7(14.6) | 25.9(13.9) | 26.7(13.9) |
*
Statistically-significant (p < 0.05) pair-wise tests between the Accel and the sensor fusion method.
**
Statistically-significant (p < 0.01) pair-wise tests between the Accel and the sensor fusion method.