This paper proposed a scheme of using rail-free multifunctional robot in onsite repair of hydraulic turbine blade for large-scale axial-flow and Francis runners. The robot processes such functions as profile detection and measurement, air-gouging cleaning, grinding, welding and so on. The robot's main body is composed of an all-position rail-free mobile platform and a multiple degree-of-freedom (DOF) manipulator. The mobile platform, on which the manipulator equipped with all kinds of exchangeable operating tools is mounted, adheres to the surface of the hydraulic turbine blade to be repaired. The operator can control the robot to carry out repairing work automatically through man-machine conversation interface of a monitoring system. Simulation of the process of welding repair using the robot was conducted. And prototypes of key components of the robot system were developed. Preliminary experimental results proved the feasibility of scheme of the repairing robot.

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Purpose – This paper aims to present a new intelligent wall-climbing welding robot system for large-scale steel structure manufacture, which is composed of robot body, control system and welding system. Design/methodology/approach – The authors design the robot system according to application requirements, validate the design through simulation and experiments and use the robot in actual production. Findings – Experimental results show that the robot system satisfies the demands of automatic welding of large-scale ferromagnetic structure, which contributes much to on-site manufacturing of such structures. Practical implications – The robot can work with better quality and efficiency compared with manual welding and other semi-automatic welding devices, which can much improve large-scale steel structure manufacturing. Originality/value – The robot system is a novel solution for large-scale steel structures welding. There are three major advantages: the robot body with reliable adsorption ability, large payload capability and good mobility which meet the requirements of welding; the control system with good welding seam tracking accuracy and intelligent automatic welding ability; and friendly human – computer interface which makes the robot easy to use.