Portable 7 DOF Scanning Arm For Non-destructive Inspection Of Objects With Unknown Geometry

The aim of this work is to develop a dextrous and adaptive robotic scanning system that can be carried by mobile climbing and walking robots to perform non-destructive testing (NDT) of remotely located infrastructure. To achieve this aim, a seven-axis lightweight robot arm has been especially developed for NDT [1]. The redundant degree of freedom is of advantage in cases such as avoiding obstacles in the workspace and joint limit avoidance. [2] The design is for portability, dexterity and ruggedness in an industrial environment. It weighs 23 kg and assures a repeatability of one millimetre. For ultrasonic NDT, the arm scans imprecisely known contoured surfaces by keeping the sensor probe normal to the test surface while maintaining constant contact forces with it, thereby ensuring good data acquisition. This is difficult to achieve when the surface is not known accurately as would be the case in test surfaces located remotely and in hazardous environments. An ability to adaptively modify a planned scan trajectory to deal with surface uncertainty would ensure better data acquisition. Further progress and new results on the subject of surface adaptation and NDT ultrasonic data acquisition are presented here. The focus is on the quality of data gathered from the NDT inspection system when combined with the robot’s trajectory motion.