The Effects of a Reduced Force Aerial Bucket Control on Upper Extremity Muscular Demands as Assessed with Surface Electromyography
Date of Award
Master of Science (MS)
A common control for operating aerial bucket trucks for utility companies in North America is called a pistol grip control. Based upon many anecdotal reports of forearm muscle fatigue from workers using this control, Prof. Richard Marklin began an EPRI-sponsored study in 2016 using EMG to determine muscle fatigue of workers while they used the pistol grip. Muscle activity recorded by EMG is a measure of the magnitude of muscle force under controlled conditions. This study confirmed the reports of muscle fatigue in extensor digitorum communis (EDC) muscle in the right forearm. The next phase of the study was to design and build a self-contained, battery-powered replacement for the pistol grip that could reduce the required input force and therefore muscle fatigue in the EDC. This new design is called the reduced-force pistol grip. The reduced-force pistol grip was then tested in a 20-participant laboratory study using EMG to quantify the reduction in muscle fatigue of the right arm. This laboratory study showed that there was a decrease in muscle activity of the right EDC while using the reduced force (50% reduced force) pistol grip as compared to a conventional force pistol grip currently used on utility trucks. The results of the truck to line full trials, which are the most representative of actual movements of the pistol grip in the field, showed that the reduction of 50% required input force produced a meaningful reduction in muscle activity of 5.6%. EMG results provide evidence that the reduced force pistol grip decreases the risk of muscle fatigue of line workers who operate the pistol grip. EMG results also corroborate reports of muscle fatigue from utility line workers who operate the pistol grip with conventional force levels. This study was the first to quantify muscular loading of an aerial bucket pistol grip control and results of the redesigned pistol grip show promise for improving the occupational health of electric utility line workers.