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Here, we present a standardized method for measurement of the hand transmitted vibration from handles of a single-axle tractor with special reference to changes in grip force and vibration frequency.
Operators of hand tractors are exposed to high levels of hand transmitted vibration (HTV). This vibration, which can be both irksome and hazardous to human health, is imparted to the operator via his or her hands and arms. However, a standardized method for measuring HTV of hand tractors has yet to be defined. The aim of the study was to present an experimental method for the investigation of the biodynamic response and vibration transmissibility of the hand-arm system during the operation of a hand tractor in a stationary mode. Measurements were performed with ten subjects using three grip forces and three handle vibration levels to examine the influences of the hand pressure and frequency on hand transmitted vibration (HTV). The results indicate that the tightness of grip on the handle influences the vibration response of the hand-arm system, especially at frequencies between 20 and 100 Hz. The transmission of lower frequencies in the hand-arm system was relatively unattenuated. In comparison, attenuation was found to be quite marked for higher frequencies during the operation of the hand tractor. The vibration transmissibility to different parts of the hand-arm system decreased with the increase of the distance from the vibration source. The proposed methodology contributes to the collection of consistent data for the evaluation of operator vibration exposure and the ergonomics development of hand tractors.
Hand tractors, also known as power tillers, are widely used in developing countries for the land preparation of small fields. The field operation of a hand tractor involves walking behind the machine and holding its handles to control its movement. The operators of hand tractors are exposed to high levels of vibration, which could be attributed to the small single cylinder engine and lack of suspension system of hand tractors1. The hand-arm vibration syndrome (HAVS)2 can be caused by long-period endurance from the vibration, named hand transmitted vibration (HTV), which generated by the hand tractor and received by the o....
All procedures were approved by the Ethics Committee of Chongqing University of Technology and each subject provided written informed consent prior to participation in this study.
1. Hand tractor preparation
The experiment was carried out in the laboratory (air temperature 22.0 °C ± 1.5 °C) on ten healthy subjects (Table 2) during the operation of a hand tractor in a stationary condition.
Following the protocol, vibration acceleration data were collected from the handle of the hand tractor, as well as the back of the hand, the wrist, the arm, and the shoulder of each subject. The spectrum of the vibration acceleration occurring at the handle (input to the hand) was .......
The protocol presented in this study was established based on HTV standards4,5,24, and was developed as the standard steps for the measurement of the HTV of the human hand-arm system during the operation of a hand tractor in a stationary condition. This condition is the most stable state of the hand tractor to help ensure the reliable measurement of the vibration actually transmitted to the hand and arm. The range of variables c.......
The authors have nothing to disclose.
This work was supported by the Natural Science Foundation of Chongqing, China (cstc2019jcyj-msxmX0046), the project of Chongqing Education Commission of China (KJQN202001127), and the project of Banan District Science and Technology Commission, Chongqing, China (2020TJZ010). The authors would like to thank Prof. Yan Yang for providing the test site. We are also grateful to Dr. Jingshu Wang and Dr. Jinghua Ma for their guidance of using the vibration measurement instrumentation. Thanks are also due to the subjects for their wholehearted cooperation during the experiments.
....Name | Company | Catalog Number | Comments |
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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