Elsevier

Applied Ergonomics

Volume 98, January 2022, 103571
Applied Ergonomics

Development and evaluation of attachable anti-vibration handle

https://doi.org/10.1016/j.apergo.2021.103571Get rights and content

Highlights

  • New type of spring-based handle was designed.

  • New spring-based handle was compared with the traditional handle in various aspects.

  • New type of spring-based handle reduced HAV value by 61.1%.

  • New type of spring-based handle can maintain neutral wrist posture while harvesting.

  • This spring-based handle has a universal design that can be used with other tools.

Abstract

Blueberry production has skyrocketed in the past two decades due to an exponential increase in consumer demand around the world. Hand harvesters are used, avoiding damage to the fruit and increasing harvesting efficiency multifold when compared with that of hand-picking. The downside of these hand harvesters is their high Hand Arm Vibration (HAV), which is very dangerous for the worker and can cause hand-arm vibration syndrome (HAVS). The aim of this study is to propose a spring-based anti-vibration handle that can be attached to vibrating equipment (blueberry hand harvester). Four different parameters were measured for the developed spring-based handles: hand arm vibration, wrist posture, muscle activity, and subjective discomfort rating. Results have shown that the use of a spring-based handle can reduce HAV by 61.1%, which is within the exposure limit values (ELV) defined by the European Union.

Introduction

The world's top blueberry producing countries in 2020 were the USA (269,257 tonnes), Canada (178,745 tonnes), and Mexico (29,067 tonnes) (AtlasBig, 2020). Blueberry production and demand have grown rapidly due to the fruit's link with health benefits. Large-scale blueberry harvesting is accomplished using commercial over-the-row (OTR) mechanical harvesters (DeVetter et al., 2019; Gopi et al., 2018). The advantage of using these OTR machines compared with the manual hand harvesting is that they reduce the labor time from 1200 h per hectare to 25 h per hectare and reduce the cost of harvest from $2.80 per kg to $0.26 per kg (DeVetter et al., 2019; Gopi et al., 2018). On the other hand, there are also two principal drawbacks of using the OTR harvester. Firstly, the blueberries harvested from this machine are likely to be damaged due to high mechanical impact, making them unacceptable for extended cold storage and long transport to distant consumers (Mehra, 2013). The other drawback of these OTR mechanical harvester is that, even though the OTR machines are available in the market, much of the blueberry harvesting is still done by hand because OTR machines can cost as much as $280,000 (Taylor and Burt, 2007).

According to the Ministry of Agriculture, Food and Rural Affairs, the total number of farms in Ontario is 59,728, which is comprised of 29,638 small farms, 21,279 medium farms, and 8811 large farms. As these data indicate, the majority of blueberry farming is carried out by small- and medium-sized farms. These farms rely on either hand harvesting or semi-automatic hand shakers due to the high cost of OTR machines. Manual hand harvesting is the traditional approach and is the most practiced method of fruit harvesting for achieving high quality control and minimizing tree damage (Benkeblia et al., 2011). But hand harvesting causes low harvest efficiency due to labor shortages and high labor costs. The above-mentioned hand harvesting drawbacks, in turn, effectively bottleneck sustainable development in blueberry production (Takeda F. Y., 2017). As a result, hand harvesting requires a labor time of 1200 h per hectare and costs $2.80 per kg to harvest the blueberries (Gopi et al., 2018). Manual hand harvesting is acknowledged to be one of the main risk factors for work-related musculoskeletal disorders (WMSD) (Naeini, 2014). WMSDs are mainly caused by working activities involving manual handling, heavy physical jobs, awkward postures, repetitive movements or exertions of the upper limbs, and prolonged sitting and standing (Eurofound, 2012, Fathallah, 2010, McMillan et al., 2015, Whelan et al., 2009). A study assessed WMSDs among a sample of 2580 agricultural workers using a questionnaire (Naeini, 2014). Reports of the study showed that 51% of employees in agriculture suffered from lower back pain and 35% had neck disorders (Naeini, 2014).

In a survey conducted as a part of the U.S. Department of Agriculture, the National Institute of Agriculture and Food, Specialty Crop, over 300 blueberry growers reported that they would welcome a semi-mechanical harvesting system that would cost less than the currently available OTR harvesters and reduce the high labor cost associated with manual hand harvesting (Takeda, 2017). Although the harvesting speed of semi-mechanical devices is 60% lower than the OTR machines (Takeda et al., 2017), they still harvest blueberries at a rate of about 15 times faster than manual hand harvesting (DeVetter et al., 2018). Additionally, the quality of fruit obtained from handheld harvesters is better when compared with the fruit obtained from the fully automatic OTR harvesters due to lower impact force and abrasion.

However, the greatest problem with handheld harvesters is that they induce higher level of hand arm vibrations (HAVs). Vibrations over prolonged periods of times can lead to fatigue and cause more severe issues, such as hand arm vibration syndrome (HAVS). Workers are at high risk of complications in the upper limbs. The excessive use of handheld vibrating equipment can result in a complication known as white fingers (Issever, 2003).

The problem of HAVS has been reported in several studies (Noraiman et al., 2019; Calvo et al., 2018; Kim et al., 2018; McCallig et al., 2010; Takeda et al., 2017; Welcome et al., 2014). Calvo et al. (2018) found that handheld olive beaters were causing HAVS and upper limb disorders. The research involved 5 operators, all of whom used three different kinds of electric olive beaters. The results revealed that the vibrations of each olive beaters ranged from 8 to 25 m/s2 (Calvo et al., 2018), exceeding the daily exposure action value (EAV) of 5 m/s2. It was concluded that the olive beater harvesters are at significant risk of HAVS. Noraiman, Fadzil, and Tamrin (2019) carried out a study on a Cantas machine used for palm fruit harvesting to evaluate the effect of HAVS. This study measured the vibrations experienced by workers at 39.4 m/s2, which was many-fold above the EAV (2.5 m/s2) and ELV (5 m/s2). Many of the workers were showing early signs of HAVS. The authors therefore recommended taking additional action to reduce HAV experienced by the worker. They also suggested the need to innovate a vibration-absorbing device that can be attached to equipment to reduce mechanical vibrations.

A few studies have tried to reduce these vibrations with different techniques but none of them were able to bring the vibration levels below the EAV and ELV limits for the use of handheld harvesters (Takeda et al., 2017; Welcome et al., 2014). One study reported that the use of vibration-reduction gloves reduced the vibrations received by workers hand and fingers (Welcome et al., 2014). The research found that the glove was more effective at reducing vibration in the fingers at higher frequencies, but lower frequency vibrations below 80Hz were reduced by only 3%. The frequency of vibrations that workers undergo from using the handheld harvesters is as low as 18 Hz (Manetto and Cerruto, 2013), and these vibration-reduction gloves would not be effective at absorbing vibrations from handheld harvesters. Therefore, a need exists for a vibration-reducing mechanism that would allow workers to safely operate the handheld harvesters. In another study, a bio-inspired vibration dampening structure was proposed for highly vibrating handheld jackhammers (Jing et al., 2019). The X-shaped structure has been evaluated for impact absorption because it is flexible and foldable. The finite element analysis of the bio-inspired vibration dampening exoskeleton showed that non-linear stiffness such as passive vibration was effectively controlled. However, it was also found that the exoskeleton reduces impact force more so than simple shaking or vibrations. Additionally, the complex design of several joints makes the exoskeleton vulnerable to damages and repetitive maintenance. Thus, this technique cannot be used for blueberry harvesters.

Considering the benefits of using handheld blueberry harvesters in collecting high quality berries without damaging the fruit, research is needed to develop a harvester that significantly reduces vibrations received during handheld operation. We hypothesize that spring-based handles will (1) reduce the HAV below the ELV limit, (2) reduce the amount of muscle activity in operating the shaker, (3) decrease operators’ subjective discomfort ratings, and (4) improve the wrist posture compared with the traditional hand shaker. Thus, this study will develop a spring-based anti-vibration handle with assumption that spring will reduce the HAV caused by direct contact of the worker with the vibrating equipment and reduce the risk factors of HAVS. In this paper, we compare a traditional blueberry hand shaker to the spring-based blueberry hand shaker on the basis of biomechanical and psychophysical aspects. We used size and number of springs to determine the best combination for the spring-based handle.

Section snippets

One-spring selection

There are three types of springs: tension, compression, and torsion spring. A compression spring was selected for its ability to absorb the force involved in the vibrations received from a blueberry hand harvester. A compression spring will compress induced reciprocating vibrations, thus minimizing the vibrations produced from blueberry hand shaker. The spring index (C) in most springs ranges from about 6 to 12 because a spring index below 6 is difficult to form and one higher than 12 tends to

HAV

From Table 4, it is seen that the small, one-spring handle showed the lowest HAV value at 3.86 m/s2, which is under the ELV limit (5 m/s2), and the handle without a spring showed the maximum HAV value at 9.94 m/s2. When compared with the no-spring handle (traditional handle), the small, one-spring handle reduced HAV value by 61.1%.

Table 5 shows the results from a two-way repeated measures ANOVA indicate a significant difference (p < 0.05) in HAV for size of spring, number of springs, and

Discussion

A new type of spring-based handle was designed that was attached to a semi-automatic hand shaker to reduce the risk factors of WMSDs caused by operating the semi-automatic hand shaker. In this study, we validated HAV, muscle activity, subjective discomfort rating, and wrist posture for our new spring-based handle design by comparing it with the traditional hand shaker.

The first hypothesis is proposed spring-based handles should reduce the HAV produced from the semi-automatic blueberry

Conclusion

Blueberry harvesting with a semi-automatic shaker is repetitive work, time consuming, and tiring. Operators are exposed to various risks, such as WMSDs, because they use high-vibration tools in unnatural body postures, which may especially affect the upper limbs. In this study, an attachable anti-vibration handle was developed to reduce HAV in workers on small- and medium-sized blueberry farms. The results of this study revealed that attaching the developed spring-based, attachable,

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

The study was funded by the Mitacs scholarship (grant No. 818140).

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