A specialized robotic system prototype for repairing surface profiles of hydraulic turbine blades

This article presents the steps of an ongoing R&D project aiming at designing and constructing a prototype of a specialized welding robotic system for repairing the surface of hydraulic turbine blades eroded by cavitation pitting and/or cracked by cyclic loading, reducing human risks and increasing the efficiency of the process. The robotic system has a spherical topology with 5 d.o.f., electric stepper and DC servo motors. The system has an embedded vision sensor built to produce range images by scanning laser beams on the blade surface and to construct 3-D models to locate the damaged spots to be recorded into the robot controller in 3-D coordinates, enabling the robot to repair the flaws automatically by welding in layers. The robot prototype is at final stages to be fully operational, with some remaining procedures such as computer systems integration and calibration for final tests and commissioning.