Dynamics of luffing motion of a hydraulically driven shell manipulator with revolute clearance joints

In this study, a modeling method for investigating the dynamic characteristics of a hydraulically driven shell manipulator with revolute clearance joints is presented. This model accounts for the effect of the clearance, the flexibility of the rotating beam, and the coupled dynamic characteristics of the hydraulic cylinder. A modified contact force model was developed to simulate the physical properties of realistic revolute joints with small clearances, heavy loads, and variable contact stiffnesses and damping coefficients with variations of the indentations. Considering the strong coupling relationship between the hydraulic cylinder and the flexible beam, a system equation of motion combining the state variables of the hydraulic cylinder and mechanical system was established. The complex nonlinear friction force of the hydraulic cylinder motion was constructed using a modified LuGre model, and the parameters of the friction model were identified using intelligent identification algorithms. Moreover, a test system for the shell manipulator was established to achieve experimental validation. Finally, the effects of the clearance size and the stiffness of the cylinder support on the dynamic response were investigated.(c) 2021 China Ordnance Society. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).

Automated summary

In this study, a modeling method is presented to investigate the dynamic characteristics of a hydraulically driven shell manipulator with revolute clearance joints. The model takes into account the effects of clearance, flexibility of the rotating beam, and the coupled dynamic characteristics of the hydraulic cylinder. A modified contact force model is developed to simulate the physical properties of realistic revolute joints with small clearances, heavy loads, and variable contact stiffnesses and damping coefficients. The system equation of motion, taking into consideration the strong coupling relationship between the hydraulic cylinder and the flexible beam, is established. Experimental validation is achieved through a test system for the shell manipulator, and the effects of clearance size and cylinder support stiffness on the dynamic response are investigated.