Finite Element Analysis and Tests of a High-Payload Hydraulic Manipulator of an Armored Rescue Robot in Case of Disaster

Finite element analysis (FEA) and optimal design were performed to minimize the amount of deflection and reduce the weight for accurate position control of a six-degree-of-freedom hydraulic manipulator used as an operating arm of an armored robot system for rescue in the event of a disaster. For the finite element modeling of the manipulator structure comprising various parts, such as hydraulic cylinders and five joints, the contacts between the parts, bolting, and behavior of the hydraulic fluid were considered. In the FEA, the manipulator was modeled for the unfolded or bent posture during working, and the deflection was calculated under loading with its own weight and a payload of 250 kgf. Weight reduction was achieved through topology or size optimization. An optimal design model was created for each joint component, and the internal loading obtained from structural analysis of the entire manipulator was applied as the load acting on the joint. A real-sized manipulator was manufactured, and the displacement was measured for a payload application of 250 kgf; further, these results were compared with those of the FEA. The measured displacement was 47.3 mm, and the FEA result was 43.3 mm, showing an error of 8.4%.