Musculoskeletal loading of seated occupational drivers exposed to whole-body vibration; vibration control

从事各种工作的重型公路和越野车辆的操作员，在被要求长时间坐在密闭空间内的同时，经常暴露在全身低频的高强度振动中。长时间坐在密闭空间和暴露于全身振动（WBV）被认为是脊柱压力导致腰痛（LBP）的主要来源。许多流行病学和实验室研究已经确立了职业驾驶员的腰痛与接触白带病之间的密切联系。欧委会的一项研究估计，在美国、加拿大和一些欧洲国家，所有雇员中有4%至7%暴露于潜在有害的WBV，而其他人估计，相关的年度赔偿和医疗费用约为数十亿美元。虽然目前还不存在被普遍接受的腰痛暴露与腰痛之间的关系，但假设预防伤害风险需要设计悬架座椅，以提供增强的振动和冲击隔离，以及姿势支持条件。本研究的主要目的是研究一种自适应控制的乘员座椅，包括基于磁流变液的悬浮液，以减弱传递给乘员的有害WBV，以及一个灵活和自适应的支撑表面，以提供理想的支撑条件，减少脊柱负荷。评估脊柱载荷作为坐姿和振动环境的功能，以及支撑条件，将通过不同的测量方法，包括传递振动、身体-座位界面力的分布、脊柱的相对压缩和伸展、使用表面肌电图的竖脊肌的活动，以及生物动力学和传递阻抗反应。结果将允许识别最理想的支持条件，可以减少传递振动，身体-座位力的集中，以及从生物动力学和生理因素测量的脊柱负荷。

Operators of heavy road and off-road vehicles, employed in various work sectors, are constantly exposed to high magnitudes of low frequency vibration of whole-body nature, while they are required to sit within confined space over long durations. Both, the prolonged sitting in a confined space and exposure to whole-body vibration (WBV) are believed to be the major sources of spinal stresses leading to low back pain (LBP). Many epidemiologic and laboratory studies have established strong associations between LBP among occupational drivers and exposure to WBV. An EC study has estimated that 4 to 7% of all employees in the USA, Canada and some European Countries are exposed to potentially harmful WBV, while others have estimated the associated annual compensation and medical costs in the order of several billion dollars. Although a generally accepted relationship between WBV exposure and LBP does not yet exist, it is hypothesized that prevention of injury risks requires design of suspension seats that provide enhanced isolation of vibration and shock, and postural support conditions. The primary objective of this study is to investigate an adaptively controlled occupant seat comprising a magneto-rheological fluid based suspension to attenuate the injurious WBV transmitted to the occupant, and a flexible and adaptive support surface to provide desirable support conditions that would reduce the spine loads. The assessment of spine loads as functions of the sitting and vibration environment, and support conditions will be attempted through different measures in terms of transmitted vibration, distribution of body-seat interface forces, relative compression and extension of the column, activities of erector spinae muscles using surface EMG, and biodynamic and transfer-impedance responses. The results would allow for identification of most desirable support conditions that could reduce the transmitted vibration, concentration of body-seat forces, and spine loads as measured from the biodynamic and physiological factors.