Fuzzy Control Based on Torque and Angle Method for Bolt Assembling System

Bolt assembly is one of the main assembly methods of automobile, airplane and other applications. Bolt connection is taken in many important parts of automobiles and airplanes, such as engine, transmission shaft, front and rear shock absorbers. In order to ensure the rigidity, tightness and anti-loosing ability of the threaded connection and the fatigue degree of the tension bolt, the connecting bolt must be applied with a preload. The traditional bolt assembly methods, such as torque method and torque and angle method, achieve a satisfied preload by controlling screw torque or angle as linear relationships exist between torque/angle and preload during tightening process. However, as the parameters of different batches of bolts and assembly objects vary greatly, it is difficult to establish an accurate model for the tightening system. Hence, the traditional control methods cannot achieve a satisfied control effect. To solve the problem above, this paper proposes a fuzzy control based on the torque and angle method, and it reduces the requirements of modeling accuracy of the controlled object, to improve the accuracy and consistency of torque control. In this paper, the fuzzy control algorithm proposed is simulated by Simulink, and it is proved that it still has stable control effect even when the tightening model changes.