Automatic operation is one of the main research topics in the field of construction for solving labor shortages. However, workers still perform manual work at construction sites and there is an urgent need to automate this. To automate manual work at construction sites, construction machinery requires force control that absorbs external shock impact forces and provides appropriate forces along with environmental forces. In this study, the boom/arm/bucket joints of a 0.06 m³ class excavator were electrically driven, and a series elastic actuator (SEA) was applied to satisfy these two requirements. There are few examples of SEA studies on its application in large machines with high outputs, such as excavators. We designed the structure of the SEA, conducted the control design, and fabricated an actual bench simulating a 0.06 m³ class excavator to verify its performance. The results of the bench tests show that our SEA system achieves a control accuracy and responsiveness suitable for use in manual work.

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