Ultrasonic Non-Destructive Testing System of Semi-Enclosed Workpiece with Dual-Robot Testing System

Abstract

With the rapid development of material science, more and more workpieces, especially workpieces with complex curved surfaces, are being made of composite materials. Robotic non-destructive testing (NDT) systems for complex curved surface composite material parts are being used more and more. Despite the emergence of such flexible NDT systems, the detection of semi-enclosed parts is also a challenge for robotic NDT systems. In order to overcome the problem, this paper establishes an NDT solution for semi-enclosed workpieces based on a dual-robot system of synchronous motion, in which an extension arm is installed on one of the robots and presents a trajectory planning method that always ensures the extension arm is parallel to the rotary axis of a semi-enclosed workpiece and that the ultrasonic probes are perpendicular to the workpiece surface. Trajectory analysis experiments and ultrasonic NDT experiments utilizing the optimal water path distance determined by simulation result of multi-Gaussian beam model for two types of semi-enclosed workpieces are performed with the dual-robot NDT system. Experimental results prove that the dual-robot NDT scheme functions well and the planned trajectories are correct. All the hole-shaped artificial defects with diameters ≥3 mm are detected by using 2.25 MHz ultrasonic probes through the transmission testing method. Vivid 3D C-scan image of a small diameter cylindrical workpiece based on the testing result is provided for convenience of observation.

Model of Diagnosing and Searching for Incompatibilities in Aluminium Castings

“…Ultrasonic testing was added to the model of diagnosing and searching for discrepancies because of the possibility of detecting dangerous flat and narrow-slit discontinuities with its use, which were difficult to recognize by, for example, X-ray method. In addition, this method makes it possible to precisely locate both internal and external inconsistencies in a rapid manner (rapid implementation of tests and rapid acquisition of results) [ 107 ]. Another fact supporting the use of the UT method was that it creates the possibility to perform diagnostics with one-sided access to the tested object, which is extremely important considering the specificity and constructional quantity of complicated details produced in the foundry industry [ 108 ].…”

“…The dependence (6) applies to waves with a length greater than three times the grain size [ 107 ]—thus, the dependence applies in the defectoscopy of the analysed left l .…”

“…Dependence (7) recognises losses due to beam dissection and losses related to wave damping in the material [ 107 ]: where p ( z ) represents the pressure in the ultrasonic beam at distance “ z ” from the transducer (Pa), p 0 represents the pressure generated by the transducer (Pa), z represents the distance from the transducer face along the acoustic beam axis (m), and α 1 represents the ultrasonic attenuation coefficient (dB/m).…”

“…Sensitivity correction is implemented due to transition losses. Accurate alignment of the camera and transducer is crucial as it affects the accuracy of imaging the ultrasound waveform in the tested object, and allows the accuracy of the discontinuity’s depth [ 107 ].…”

Research on the Trajectory Planning of Demolition Robot Attachment Changing

“…In our previous work, an error compensation method for changing the attachment of demolition robots was proposed, and a visualization system for the remote changing of the demolition robot attachment was developed [23,24]. After the coordinate systems of the robot's quick-hitch equipment and the attachment are obtained accurately, the motion trajectory of the quick-hitch equipment should be analyzed and planned [25] so as to provide the optimal attachment changing solution to the operator. In recent works on robot path planning research, a method for constrained motion planning based on vision was proposed, which enables a robot to move its end-effector over an observed surface [26].…”