手牵引机运行过程中人手臂系统手传振动的测量
Summary
在这里，我们提出了一种标准化的方法，用于测量单轴牵引车手柄的手传振动，并特别参考了抓地力和振动频率的变化。
Abstract
手牵引机的操作员暴露在高水平的手传振动 （HTV） 中。这种振动既令人讨厌又对人体健康有害，通过他或她的手和手臂传授给操作员。然而，衡量手扶拖拉机HTV的标准化方法尚未确定。研究的目的是提出一种实验方法，用于研究手扶拖拉机在静止模式下操作过程中手臂系统的生物动力反应和振动可传播性。用三个抓地力和三个手柄振动水平对十个受试者进行测量，以检查手部压力和频率对手部传导振动 （HTV） 的影响。结果表明，手柄的紧握会影响手臂系统的振动响应，尤其是在 20 至 100 Hz 之间的频率。手臂系统中较低频率的传输相对没有减弱。相比之下，在手牵引车操作过程中，衰减频率较高。随着与振动源距离的增加，手臂系统不同部分的振动可传输性降低。拟议的方法有助于收集一致的数据，用于评估操作员振动暴露和手扶拖拉机的人体工程学发展。
Introduction
手扶拖拉机，也称为动力耕作机，广泛用于发展中国家小田的土地准备。手扶拖拉机的现场操作包括走在机器后面，握住手柄控制机器的移动。手扶拖拉机的操作员暴露在高振动水平，这可以归因于小型单缸发动机和缺乏悬挂系统的手牵引1。手臂振动综合征 （HAVS）2 可由振动引起的长期耐久性（称为手部传动振动 （HTV），由手牵引器生成，由操作员手接收。为了评估操作员接触手扶拖拉机HTV所带来的健康风险，有必要建立手扶手系统振动响应测量方法。
手臂系统由骨骼、肌肉、组织、静脉和动脉、肌腱和皮肤3组成，直接测量HTV会带来许多问题。相关国际标准4、5提供有关测量手附近振动严重程度的指引，包括手部坐标系、加速度计的位置和安装、测量持续时间、电缆连接器问题等。然而，标准没有考虑到内在变量，如抓地力，手和手臂的姿势，个别因素等。这些因素在广泛的振动激发和测试条件下进行了广泛的研究，6、7、8、9、10、11、12、13，但不同的研究结果并不完全一致。其中许多因素没有得到充分理解，无法纳入标准方法。这一限制部分归因于人类手臂系统的复杂性、试验条件以及所采用的实验和测量技术的差异。
此外，HTV的早期测量大多在经过严格控制的条件下进行，具有理想的振动激发、抓地力和姿势条件。因此，这些测量结果和实验程序可能无法真正复制实际情况，例如手扶拖拉机的运行条件。此外，只有有限的努力来研究手牵引车的HTV与现场测量。这些测量是使用附加在操作员的手腕、手臂、胸部和头部的加速度计进行的，以测量拖拉机运输条件下的全身振动1，或在耕种在耕种场和在发动机速度14级不同级别的水下田地中呕吐的条件下进行。抓地力的作用，这可能是HTV7，8的关键因素，并没有孤立。因此，由于经营者在耕作过程中由于恶劣的环境条件而采取各种强制姿势，这些方法不适合作为标准化的测量程序。
本研究旨在为以固定模式对手扶拖拉机进行HTV测量建立可靠和可重复的程序作出贡献。图1显示实验设计的示意图图。采用了中国制造、中国农民常用的手扶拖拉机，并选派了10名科研人员作为研究对象。七台连接到拖拉机手臂系统的轻型压电加速度计用于测量振动。一个测速仪和两个薄膜压力传感器在测试期间监测发动机速度和抓地力。受试者必须按规定发动机速度和指定的抓地力按顺序操作手扶拖拉机，以获得各种操作模式的振动特性。本手稿为拖拉机手臂系统的 HTV 测量提供了详细的协议，并特别考虑了抓地力和振动频率的变化。
Protocol
所有程序均经重庆理工大学伦理委员会批准，各学科在参与本研究前均提供书面知情同意。 1. 手扶拖拉机准备 确保手扶拖拉机在充分的燃油箱下接受适当的测试，没有螺栓松动，并且不会产生其他可能导致异常振动的机械缺陷。注：本实验中使用的手扶拖拉机的规格在 表1中给出。 将手扶拖拉机放置在具有干燥、坚固和平地表面的试验场。?…
Representative Results
实验是在实验室进行（空气温度22.0°C±1.5°C）的10个健康受试者（表2）在手扶拖拉机的操作中处于静止状态。 按照协议，从手牵引车的手柄以及手背、手腕、手臂和每个主体的肩膀收集振动加速数据。获取了手柄（输入到手部）时发生的振动加速度谱。 图 8 在给定时间内，在发动机速度级别为 3500 rpm 时柄上显示时间域和 RMS 频率域加速度?…
Discussion
本研究提出的协议是根据HTV标准4、5、24建立的，是作为在固定条件下手扶拖拉机运行过程中测量人手扶手系统HTV的标准步骤而制定的。这种情况是手牵引机最稳定的状态，有助于确保可靠测量实际传送到手和手臂的振动。通过调整发动机速度和抓地力，考虑执行测试的变量范围涵盖了手牵引车的正常和安全操作范围。考虑到?…
Divulgazioni
The authors have nothing to disclose.
Acknowledgements
这项工作得到了中国重庆市自然科学基金（cstc2019jcyj-msxmX0046）、重庆市教委（KJQN2002001127）项目和中国重庆市巴南区科委（2020TJZ010）项目的支持。作者要感谢杨燕教授提供试验场。我们也感谢王景树博士和马景华博士指导使用振动测量仪器。感谢受试者在实验期间的全心合作。
Materials
| Accelerometers | PCB Piezotronics Inc. | 352C33, 356A04 | Used to measure vibration signals. Including 2 tri-axial accelerometers and 5 single-axis accelerometers. |
| CompactDAQ System | National Instruments | cRIO-9045,NI-9234 C | Used for acceleration acquisition. The system consists of a chassis and 3 data acquisition cards. |
| Digital caliper | Sanliang | 160800635 | Used to measure dimensions of the hand. |
| Digital goniometer | Sanliang | 802973 | Used to measure hand and arm posture. |
| Laptop computer | Lenovo | Ideapad 500s | To run the softwares. |
| Matlab | MathWorks Inc. | Version 2020a | Used for data processing. |
| NI SignalExpress | National Instruments | Trial version 2015 | Use to acquire, analyze and present acceleration data. |
| Tachometer | Sanliang | TM 680 | Used to measure engine speed. |
| Thin-film pressure sensing system | YourCee | n/a | Used to measure grip force. The system consists of 2 thin-film sensors, a STM32 singlechip and a LED display. |
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Citazione di questo articolo
Lu, S., Jiang, R., Xiao, X., Li, Y., Huang, X., Song, K., Chen, C., Ding, J. Measurement of the Hand Transmitted Vibration of the Human Hand Arm System During Operation of a Hand Tractor. J. Vis. Exp. (172), e62508, doi:10.3791/62508 (2021).