Twin-robot And External Axis Control Technology For Ultrasonic Testing

With the development of technology, the components of composite and complexcurved surface are widely used in aerospace and major engineering fields. However,the defects which produce in the manufacturing process of composite workpiece willseverely degrade the safety and reliability of the key parts. Aerospace manufacturingindustry must ensure the quality of production by detecting these key components.Ultrasonic NDT is one of the most effective and practical detection. In order to ensurethe testing accuracy of complex composite surface of the workpiece, the ultrasonictransducer is required to move along the normal direction of the surface. Therefore,the conventional method and equipment can not complete the efficient detection taskfor composite parts with complex surface.Six degrees of freedom joint robot can achieve arbitrary pose motion in space, soit can complete the ultrasonic test of complex surfaces with ultrasonic transducer.However, the robot can’t complete the detection task when the part has a closedsurface in one end and has narrow interior space limited by its operating space andsize. By adding some supplementary motions to the robot, the final motion combinedby the robot motion and the added motion can solve this problem effectively.. As thesupplementary motion is relatively independent of the robot movement, it is requiredto coordinate the two kinds of movements. In addition, applied to the robot as a load,the supplementary motion mechanism can affect motion performance of the robot. Soit is necessary to optimize its structure.In this paper, by adding moving shaft and extension pole(the added pole is calledas extension pole) to the twin-robot ultrasonic testing system, the writer solves theultrasonic automatic detection of rotating composite parts with a close end, analysisthe composition characteristics of the system and researchs the control methods of thesystem.The main content consists of two parts. One is the planning of the scanningpath, including scanning trajectory planning strategies, coordinate transformation ofpose point and the deceleration planning of trajectory. The other is thesynchronization control between the robot and the external pole, including thesynchronization control of the two robots and the synchronization control between therobot and the external pole and the ultrasound signal acquisition synchronoustriggering. Verify the synchronized motion and trigger performance through experiments and evaluate the detection performance of the system.