Kinematic Control of a Mobile Robot Performing Manufacturing Tasks on Non-Planar Surfaces

Mobile robotic systems are becoming viable technologies for automating manufacturing processes in fields that traditionally have seen little automation. Such fields include pipeline construction, green energy development, infrastructure and shipbuilding. To operate in these environments, the mobile robotic platform must provide controlled motion of a manufacturing toolset over the surface of a structure which is generally non-planar. One such example is welding a seam along a non-flat ship hull where the surface may consist of sections resembling common geometric shapes such as cylinders or spheres and the tool must follow a path defined by the weld seam. This paper will present a kinematic control approach applicable to one mobile robot topology performing a task on a cylindrical surface. This method is readily generalized to other robot topologies or surface geometries. The method is based on a kinematic model that predicts the robot motion and configuration joint parameters while on a nonplanar surface with the desired motion prescribed in local tool space. The effort is motivated by a practical application of welding on steel hulls or other surfaces and the results will be compared with these empirical experiences. A discussion of how these results can be used to guide future design of mobile robot platforms for manufacturing is provided.