Climbing Robot Cell For Fast And Flexible Manufacture Of Large Scale Structures

This paper describes the specification stages of a project which seeks to modernise and take into the future the technology of the manufacture of large fixed welded structures such as box girder bridges, storage tanks, ships and other steel fabrications which arise on construction sites, in large chemical and foodstuff plants, on offshore oil platforms etc, bringing the world of fast and flexible manufacturing to areas were construction is presently carried out by traditional use of manual labour, scaffolding and cranes and the inconvenient delivery by road of large factory prefabricated components. The Project will achieve this by creating a transportable manufacturing cell (CROCELLS) consisting of a team of cooperating climbing robot work tools whose activities are coordinated and integrated through a central intelligence. Unlike factory based cells the robot work tools must be mobile and small so that they are able to climb over long distances, to great heights and over curved surfaces and surfaces with ridges or protusions such as nodal joints providing many technical robotics problems to be solved. Small robots have payload limitations but the essence of the cooperating robot concept is that large payloads of work tools can be achieved with small robots by distributing the payload over several robots. Each robot will be dedicated to a different task to optimise overall system performance, hence there could be be a surface profiler and navigator, welder, bolt and rivet placer, hot weld quality inspector, and cold weld inspector on separate platforms. The cell will be deployed through every stage of a product life cycle, during construction where the system will perform instant weld quality diagnostics and repairs, in service inspection and repair, and final lifetime assessment. The CROCELLS concept is described in detail and system specifications are given which arise from an analysis of the industrial problems to be solved in a first exploitation phase addressed to the business requirements of the end users in the project. Then the hardware and software Architecture optimized for these specifications is presented for a prototype system presently under construction. Presently large fabrications on construction sites suffer from long fabrication times prescribed by traditional methods. The proposed mobile manufacturing cell will greatly reduce these times with economic benefits estimated at 630 M€ per annum in save time and 1956M€ per annum equipment sales taking EU export markets into account, with data for the global market being typically a factor of 4 higher