Iterative Inverse Kinematics of an Underactuated 5 D.o.F. Service Robot for Repairing Hydraulic Turbine Blades

José Maurício S T Motta¹; Carlos Humberto LLanos Quintero¹; Renato Coral Sampaio¹; Guilherme Caribé de Carvalho¹; Sadek C Absi Alfaro¹

¹ Universidade de Brasilia

doi:10.20906/CPS/COB-2015-1627

Resumo

This paper presents and discusses partial results of an ongoing R&D project aiming to design and build a fully automated prototype of a specialized robotic welding system for repairing hydraulic turbine surfaces eroded by cavitation pitting and/or cracks produced by cyclic loading. The system has an embedded vision sensor built to acquire range images by laser scanning over the blade surface and produce 3D models to locate the damaged spots to be registered in a 3D coordinate system into the robot controller, enabling the robot to repair the flaws automatically by welding in layers. The paper is focused on the robot kinematic model and proposes an iterative algorithm to solve the inverse kinematics problem of the underactuated robot with 5 degrees-of-freedom. The iterative algorithm makes use of data collected from a vision sensor to ensure that the welding gun axis is perpendicular to the blade surface. Experimental results show that the iterative algorithm to perform the inverse kinematics proved to be very efficient.

Palavras-chave: Turbine Blade Repairing; Iterative Inverse Kinematics; Automated Welding Robots; Underactuated Robots