The effectiveness of napier harvesting machine in reducing postural risk among napier harvester in Perlis
Mohd Khairul Faizi, Abd Rahman
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Most farmworkers in the small and medium Napier industry are using conventional method for harvesting works. Therefore, they are extremely exposed to the risk of low back pain (LBP) disease which is one of the musculoskeletal disorders (MSDs) typical problems. Referring to the Rapid Upper Limb Assessment (RULA), and Rapid Entire Body Assessment (REBA), conventional harvesting works was highly risk to undergo LBP due to extreme stooped posture and high of low back biomechanical loading. Based on the body score survey result, there were 95% of respondents suffering of LBP. Hence, the objective of this project is to identify proper working posture thus to design the Napier harvesting ergonomics engineering intervention in order to replace the use of machetes in conventional harvest. The comprehensive laboratory studies were conducted by focusing on stooped posture by using electromyography (EMG). Three kinds of stooped posture condition were investigated: free load stooped; with 10 kg load stooped; with support holder stooped. Eleven male subjects were selected to demonstrate these stooped conditions with four difference flexion levels. The EMG signal data then was analyzed by ANOVA with α (0.05) and plotted into scatterplot, and then linear regression was constructed to generate the linear mathematical equation. The ANOVA showed the significant difference with p-value (0.001) and the boxplot proved that stooped with support holder give better result. By the laboratory experiment findings, the ergonomics engineering intervention was properly designed. The intervention was developed in prototype with motorizes assistance and semi-automated system. A prototype field evaluation has been conducted to monitor the muscle activities with focusing on the lower back region by using EMG. The EMG data then was analyzed by the t-test with α (0.05). Ten volunteered farmworker is randomly picked to simulate the harvesting process. Based on the boxplot, the results shown reduction of back muscle activities as compared to the conventional method due to working posture improvement. The intervention prototype had a significant difference in the muscle activities with p-value (0.00034). Besides, the RULA and REBA also shows better score as concrete evidence in improving body posture during harvesting work with this new method. Furthermore, the harvest cycle time was improved about 70.2% where it’s getting better production outputs. The t-test analysis also shown the significance difference with p-value (0.0000373) and based on boxplot, the intervention harvest depicted better cycle time. As conclusions, optimized working posture along with the assistance of intervention prototype in the Napier harvesting process is suggested since the data provided in this project show that it could decrease the risk of low back pain. Apparently, this study also encourage of generating the innovation in designing new tools to increase the agriculture workers’ performance.