Incremental Inspection For Microrobotic Quality Assurance

This paper addresses inspection techniques that can be performed by microrobots used for fabricating three dimensional structures. In contrast to most commercial rapid prototyping processes, the parallelism afforded by microrobot teams allows incremental inspection of structures during assembly. In the present case, this approach is applied to parts fabricated from carbon fiber struts bonded with UV-cured epoxy. Preliminary tests involving thermal and vibrational inspection methods are described and compared with the results of FEA models of the joints. Vibrational inspection performed by microrobots and recorded using a directional microphone, characterizes bond joint natural frequency with good resolution (an average measurement standard deviation of 5Hz over a range of 650-1215 Hz). These effective stiffness measurements are correlated with ultimate bond strength as well. The measurements are sufficient to distinguish between joints that do or do not have desired amounts of adhesive.