Erickson Brett, Hosseini Masih A, Mudhar Parry Singh, Soleimani Maryam, Aboonabi Arina, Arzanpour Siamak, Sparrey Carolyn J
School of Mechatronic Systems Engineering, Simon Fraser University, 250-13450 102 Ave., Surrey, BC, V3T 0A3, Canada.
MobiSafe Systems Inc., Room 5330 250-13450 102 Avenue, Surrey, BC, V3T 0A3, Canada.
J Neuroeng Rehabil. 2016 Mar 2;13:20. doi: 10.1186/s12984-016-0128-7.
To reduce the occurrence of wheelchair falls and to develop effective protection systems, we aimed to quantify sideways tip and fall dynamics of electric power wheelchairs (EPWs). We hypothesized that driving speed, curb height and angle of approach would affect impact forces and head injury risk for wheelchair riders. We further expected that fall dynamics and head injury risk would be greater for unrestrained riders compared to restrained riders.
Sideways wheelchair tip and fall dynamics were reconstructed using a remotely operated rear wheel drive EPW and a Hybrid III test dummy driving at different approach angles (5 to 63°) over an adjustable height curb (0.30 to 0.41 m) at speeds of 0.6-1.5 m/s. Rigid body dynamics models (Madymo, TASS International, Livonia, MI) were developed in parallel with the experiments to systematically study and quantify the impact forces and the sideways tip or fall of an EPW user in different driving conditions.
Shallower approach angles (25°) (p < 0.05) and higher curbs (0.4 m) (p < 0.05) were the most significant predictors of tipping for restrained passengers. Unrestrained passengers were most affected by higher curbs (0.4 m) (p < 0.005) and fell forward from the upright wheelchair when the approach angle was 60°. Head impact forces were greater in unrestrained users (6181 ± 2372 N) than restrained users (1336 ± 827 N) (p = 0.00053). Unrestrained users had significantly greater head impact severities than restrained users (HIC = 610 ± 634 vs HIC = 29 ± 38, p = 0.00013) and several tip events resulted in HICs > 1000 (severe head injury) in unrestrained users.
Sideways tips and forward falls from wheelchairs were most sensitive to curb height and approach angle but were not affected by driving speed. Sideways tips and falls resulted in impact forces that could result in concussions or traumatic brain injury and require injury prevention strategies. Seat belts eliminated the risk of falling from an upright chair and reduced head impact forces in sideways wheelchair tips in this study; however, their use must be considered within the ethical and legal definitions of restraints.
为了减少轮椅跌倒的发生并开发有效的保护系统，我们旨在量化电动轮椅（EPW）的侧向倾翻和跌倒动力学。我们假设行驶速度、路缘高度和接近角度会影响轮椅使用者的冲击力和头部受伤风险。我们进一步预期，与系安全带的使用者相比，未系安全带的使用者的跌倒动力学和头部受伤风险会更高。
使用遥控后轮驱动的电动轮椅和Hybrid III测试假人，以0.6 - 1.5 m/s的速度在高度可调的路缘（0.30至0.41 m）上以不同的接近角度（5至63°）行驶，重建电动轮椅的侧向倾翻和跌倒动力学。在实验的同时开发刚体动力学模型（Madymo，TASS International，Livonia，密歇根州），以系统地研究和量化电动轮椅使用者在不同驾驶条件下的冲击力以及侧向倾翻或跌倒情况。
较浅的接近角度（25°）（p < 0.05）和较高的路缘（0.4 m）（p < 0.05）是系安全带乘客倾翻的最显著预测因素。未系安全带的乘客受较高路缘（0.4 m）影响最大（p < 0.005），当接近角度为60°时，会从直立的轮椅向前跌倒。未系安全带的使用者的头部冲击力（6181 ± 2372 N）大于系安全带的使用者（1336 ± 827 N）（p = 0.00053）。未系安全带的使用者的头部撞击严重程度明显高于系安全带的使用者（头部损伤标准值[HIC] = 610 ± 634 vs HIC = 29 ± 38，p = 0.00013），并且在未系安全带的使用者中，几次倾翻事件导致HIC > 1000（严重头部损伤）。
轮椅的侧向倾翻和向前跌倒对路缘高度和接近角度最为敏感，但不受行驶速度影响。侧向倾翻和跌倒会产生可能导致脑震荡或创伤性脑损伤的冲击力，需要采取预防伤害的策略。在本研究中，安全带消除了从直立椅子上跌倒的风险，并在轮椅侧向倾翻时降低了头部冲击力；然而，安全带的使用必须在约束的伦理和法律定义范围内加以考虑。
