Development of Two-DOF Simultaneous Gravity Compensator for Mobile Manipulator

A manipulator mounted on a mobility platform requires a design that simultaneously meets the demands for lightweight, compactness, and energy efficiency. A gravity compensator is an effective solution that mechanically offsets the gravity torque caused by the weight of the manipulator links, enabling the use of low-capacity motors while maintaining performance comparable to conventional systems. However, existing gravity compensators face notable challenges in terms of spatial efficiency and durability. To address these challenges, this study developed the two-DOF simultaneous gravity compensator based on a spring and slider-crank mechanism to compensate for the gravity torque generated by two consecutive pitch joints. Experimental results demonstrated a high torque compensation rate of 71.58% and a power reduction rate of 32.23% across the full range of motion of the two joints, further confirming consistency with theoretical predictions.