Static stiffness modeling for optimizing drilling and riveting robots
GUAN Liwen1, CHEN Zhixiong2, LIU Chun3, XUE Jun4
1. School of Mechanical Engineering, Tsinghua University, Beijing 100084, China; 2. School of Mechanical and Electrical Engineering, University of Electronic Science and Technology of China, Chengdu 611173, China; 3. Chengdu Aircraft Industrial (Group) Co., Ltd., Chengdu 610092, China; 4. AVIC Manufacturing Technology Institute, Beijing 100025, China
Abstract：Automatic robotic drilling and riveting greatly improve aircraft assembly quality and flexibility while reducing costs, so automatic drilling and riveting are being widely used for aircraft assembly. However, almost all robotic drilling and riveting systems are based on six degrees of freedom serial robots. However, these robots have an inherent weakness due to their poor rigidity. Large pressing and drilling forces during drilling and riveting can lead to deformation and even flutter of the robot end actuator, which seriously affect the drilling and riveting accuracy and quality. A static stiffness model of a drilling and riveting robot is developed with joint stiffness measurements to predict robot joint stiffnesses. A stiffness evaluation index is then used to characterize the robotic arm stiffness in the working space. The stiffness index can be used to optimize the robot position and posture for a specific operation using a particle swarm algorithm to improve the stiffness. This improves the system stability and quality.
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2021, Vol. 61 
