# Demonstration of the Effect of Centre of Mass Height on Postural Sway Using Accelerometry for Balance Analysis

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## Abstract

**:**

## 1. Introduction

## 2. Hypothesis of the Study

## 3. Accelerometry-Based Sway Measurement

_{x}, a

_{y}and a

_{z}, are given by cos(α), cos(β) and cos(γ), respectively. The projected distance is D, and the position of the COM from the ground surface is d

_{z}.

## 4. Accelerometry Measurement Devices

## 5. Measurement Apparatus

_{y}) of each plumb bob from the origin (shown as 0 in Figure 5a) was measured manually using a tape measure. Simultaneously, the accelerometry data from the three axes of the accelerometer (X, Y and Z) were wirelessly transmitted to the receiving device (described in Section 4). The algebra described in Section 3 was used to determine accelerometry-based angles and ground projected displacements, and these were compared with the manual measurements.

#### Data Analysis

_{y}) from the accelerometry data was determined using Equation (7) and averaged (d

_{ya}) over the number of samples, N (i.e., measurement interval = 60 seconds $\times $ 60 samples per second = 3600 samples).

^{®}statistical package. T-test, correlation and regression analysis were carried out to interpret the measurements.

## 6. Results and Discussion

#### 6.1. T-test

#### 6.2. Correlation and Linear Regression Analysis

## 7. Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

## References

- Winter, D.; Patla, A.; Prince, F.; Ishac, M.; Gielo-Perczak, K. Stiffness control of balance in quiet standing. J. Neurophysiol.
**1998**, 80, 1211–1221. [Google Scholar] [CrossRef] [PubMed] [Green Version] - Lafond, D.; Duarte, M.; Prince, F. Comparison of three methods to estimate the center of mass during balance assessment. J. Biomech.
**2004**, 37, 1421–1426. [Google Scholar] [CrossRef] - Rosker, J.; Markovic, G.; Sarabon, N. Effects of vertical center of mass redistribution on body sway parameters during quiet standing. Gait Posture
**2011**, 33, 452–456. [Google Scholar] [CrossRef] [PubMed] - Shumway-Cook, A.; Horak, F. Assessing the influence of sensory interaction on balance. Phys. Ther.
**1986**, 66, 1548–1550. [Google Scholar] [CrossRef] [PubMed] - Corriveau, H.; Hébert, R.; Prince, F.; Raîche, M. Postural control in the elderly: An analysis of test-retest and interrater reliability of the COP-COM variable. Arch. Phys. Med. Rehabil.
**2001**, 82, 80–85. [Google Scholar] [CrossRef] [PubMed] - Hasan, S.; Robin, D.; Szurkus, D.; Ashmead, D.; Peterson, S.; Shiavi, R. Simultaneous measurement of body center of pressure and center of gravity during upright stance. Part I: Methods. Gait Posture
**1996**, 4, 1–10. [Google Scholar] [CrossRef] - Hasan, S.; Robin, D.; Szurkus, D.; Ashmead, D.; Peterson, S.; Shiavi, R. Simultaneous measurement of body center of pressure and center of gravity during upright stance. Part II: Amplitude and frequency data. Gait Posture
**1996**, 4, 11–20. [Google Scholar] [CrossRef] - Błaszczyk, J.W.; Beck, M.; Sadowska, D. Assessment of postural stability in young healthy subjects based on directional features of posturographic data: vision and gender effects. Acta Neurobiol. Exp. (Warsaw)
**2014**, 74, 433–442. [Google Scholar] - Błaszczyk, J.W. The use of sway vector for the assessment of postural instability. Gait Posture
**2016**, 44, 1–6. [Google Scholar] [CrossRef] - Kavanagh, J.; Menz, H. Accelerometry: A technique for quantifying movement patterns during walking. Gait Posture
**2008**, 28, 1–15. [Google Scholar] [CrossRef] - Yang, C.; Hsu, Y. A Review of Accelerometry-Based wearable motion detectors for physical activity monitoring. Sensors
**2010**, 10, 7772–7788. [Google Scholar] [CrossRef] [PubMed] - Mathie, M.; Coster, A.; Lovell, N.; Celler, B. Accelerometry: providing an integrated, practical method for long-term, ambulatory monitoring of human movement. Physiol. Meas.
**2004**, 25, R1–R20. [Google Scholar] [CrossRef] [PubMed] [Green Version] - Oshima, Y.; Kawaguchi, K.; Tanaka, S.; Ohkawara, K.; Hikihara, Y.; Ishikawa-Takata, K.; Tabata, I. Classifying household and locomotive activities using a triaxial accelerometer. Gait Posture
**2010**, 31, 370–374. [Google Scholar] [CrossRef] [PubMed] - Khan, A.; Hammerla, N.; Mellor, S.; Plötz, T. Optimising sampling rates for accelerometer-based human activity recognition. Pattern Recognit. Lett.
**2016**, 73, 33–40. [Google Scholar] [CrossRef] - Chien, J.C.; Hirakawa, K.; Shieh, J.; Guo, H.W.; Hsieh, Y. A simple method for walking posture analysis using accelerometers. In Proceedings of the 2016 International Conference on Communication Problem-Solving (ICCP), Taipei, Taiwan, 7–9 September 2016; pp. 1–3. [Google Scholar]
- Cohen, H.; Blatchly, C.A.; Gombash, L.L. A study of clinical test of sensory interaction and balance. Phys. Ther.
**1993**, 73, 346–351. [Google Scholar] [CrossRef] - Martínez-Ramírez, A.; Lecumberri, P.; Gómez, M.; Rodriguez-Mañas, L.; García, F.; Izquierdo, M. Frailty assessment based on wavelet analysis during quiet standing balance test. J. Biomech.
**2011**, 44, 2213–2220. [Google Scholar] [CrossRef] - Mancini, M.; Salarian, A.; Carlson-Kuhta, P.; Zampieri, C.; King, L.; Chiari, L.; Horak, F. ISway: a sensitive, valid and reliable measure of postural control. J. Neuroeng. Rehabil.
**2012**, 9, 1–8. [Google Scholar] [CrossRef] [Green Version] - Spain, R.; St George, R.; Salarian, A.; Mancini, M.; Wagner, J.; Horak, F.; Bourdette, D. Body-worn motion sensors detect balance and gait deficits in people with multiple sclerosis who have normal walking speed. Gait Posture
**2012**, 35, 573–578. [Google Scholar] [CrossRef] [Green Version] - Gago, M.; Fernandes, V.; Ferreira, J.; Silva, H.; Rocha, L.; Bicho, E.; Sousa, N. Postural stability analysis with inertial measurement units in Alzheimer's disease. Dement. Geriatr. Cogn. Disord. Extra
**2014**, 4, 22–30. [Google Scholar] [CrossRef] [Green Version] - Goldring, D.; Londe, S.; Sivakoff, M.; Hernandez, A.; Britton, C.; Choi, S. Blood pressure in a high school population. J. Pediatrics
**1977**, 91, 884–889. [Google Scholar] [CrossRef] - Alberts, J.; Hirsch, J.; Koop, M.; Schindler, D.; Kana, D.; Linder, S.; Campbell, S.; Thota, A. Using accelerometer and gyroscopic measures to quantify postural stability. J. Athl. Train.
**2015**, 50, 578–588. [Google Scholar] [CrossRef] [PubMed] [Green Version] - Hiiragi, Y. Evaluation of postural sway using a triaxial accelerometer. Rigakuryoho Kagaku
**2004**, 19, 305–309. [Google Scholar] [CrossRef] [Green Version] - Marvel, C.A. quantitative measure of postural sway deficits in schizophrenia. Schizophr. Res.
**2004**, 68, 363–372. [Google Scholar] [CrossRef] [PubMed] - Mayagoitia, R.; Lötters, J.; Veltink, P.; Hermens, H. Standing balance evaluation using a triaxial accelerometer. Gait Posture
**2002**, 16, 55–59. [Google Scholar] [CrossRef] - Najafi, B.; Lee-Eng, J.; Wrobel, J.S.; Goebel, R. Estimation of center of mass trajectory using wearable sensors during golf swing. J. Sports Sci. Med.
**2015**, 14, 354–363. [Google Scholar]

**Figure 1.**Tracing of the trajectory of the accelerometer on ground [25].

**Figure 5.**Test measurement apparatus (

**a**) schematic diagram with only one of the three plumb bobs shown; (

**b**) actual apparatus.

**Figure 6.**Relationship between the displacements and angles from the accelerometry device (

**a**) COM = 50 cm (

**b**) COM = 75 cm (

**c**) COM = 100 cm.

**Figure 10.**Accelerometry-based sway plots from two healthy adult subjects standing on a foam surface with eyes closed. (

**a**) The actual COM height value was used in determining the displacements, (

**b**) COM height was set to 1 to produce a normalized sway displacement plot. (

**c**,

**d**) are as figures (

**a**,

**b**), but for the second subject.

Measurement Number | Angle $\mathit{\gamma}$ (Degrees) | Position 1 (Displacements at COM = 50 cm) | Position 2 (Displacement at COM = 75 cm) | Position 3 (Displacement at COM = 100 cm) |
---|---|---|---|---|

1 | 0 | 0 | 0 | 0 |

2 | 5 | 5 | 7 | 9 |

3 | 10 | 9 | 13 | 17 |

4 | 15 | 12 | 19 | 25 |

5 | 20 | 17 | 25 | 34 |

6 | 25 | 21 | 31 | 42 |

7 | 30 | 25 | 36 | 50 |

8 | 35 | 29 | 43 | 56 |

9 | 40 | 32 | 50 | 65 |

10 | 45 | 35 | 52 | 70 |

11 | 50 | 39 | 58 | 77 |

12 | 55 | 41 | 60 | 82 |

13 | 60 | 44 | 65 | 87 |

14 | 65 | 45 | 68 | 90 |

15 | 70 | 48 | 70 | 95 |

16 | 75 | 48 | 72 | 97 |

17 | 80 | 49 | 73 | 98 |

18 | 85 | 49 | 74 | 99 |

19 | 90 | 50 | 75 | 100 |

Mean = 31.5 cm Standard deviation = 16.6 cm | Mean = 46.9 cm Standard deviation = 24.8 cm | Mean = 62.8 cm Standard deviation = 33.3 cm |

Measurement Number | Angle $\mathit{\gamma}$ (Degrees) | Position 1 (Displacements at COM = 50 cm) | Position 2 (Displacement at COM = 75 cm) | Position 3 (Displacement at COM = 100 cm) |
---|---|---|---|---|

1 | 0.80 | 0.69 | 1.04 | 1.39 |

2 | 5.09 | 4.44 | 6.66 | 8.87 |

3 | 9.12 | 7.93 | 11.89 | 15.85 |

4 | 14.42 | 12.45 | 18.68 | 24.90 |

5 | 20.05 | 17.14 | 25.72 | 34.29 |

6 | 25.01 | 21.14 | 31.72 | 42.28 |

7 | 29.35 | 24.51 | 36.76 | 49.02 |

8 | 34.66 | 28.44 | 42.65 | 56.87 |

9 | 40.27 | 32.32 | 48.47 | 64.63 |

10 | 44.96 | 35.33 | 52.78 | 70.66 |

11 | 50.39 | 38.52 | 57.78 | 77.05 |

12 | 55.65 | 41.28 | 61.92 | 82.57 |

13 | 61.02 | 43.74 | 65.61 | 87.48 |

14 | 65.06 | 45.34 | 68.01 | 90.68 |

15 | 71.02 | 47.28 | 70.92 | 94.56 |

16 | 75.33 | 48.37 | 72.55 | 96.74 |

17 | 80.48 | 49.31 | 73.97 | 98.62 |

18 | 84.17 | 49.74 | 74.61 | 99.48 |

19 | 89.28 | 50.00 | 74.99 | 99.99 |

Statistics | Mean = 31.5 cm Standard deviation = 16. 7 cm | Mean = 47.2 cm Standard deviation = 25.0 cm | Mean = 62.9 cm Standard deviation = 33.3 cm |

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**MDPI and ACS Style**

Ojie, O.O.D.; Saatchi, R.; Saatchi, M.
Demonstration of the Effect of Centre of Mass Height on Postural Sway Using Accelerometry for Balance Analysis. *Technologies* **2020**, *8*, 20.
https://doi.org/10.3390/technologies8020020

**AMA Style**

Ojie OOD, Saatchi R, Saatchi M.
Demonstration of the Effect of Centre of Mass Height on Postural Sway Using Accelerometry for Balance Analysis. *Technologies*. 2020; 8(2):20.
https://doi.org/10.3390/technologies8020020

**Chicago/Turabian Style**

Ojie, Oseikhuemen Osemekhian Davis, Reza Saatchi, and Mahdieh Saatchi.
2020. "Demonstration of the Effect of Centre of Mass Height on Postural Sway Using Accelerometry for Balance Analysis" *Technologies* 8, no. 2: 20.
https://doi.org/10.3390/technologies8020020