Kinematic and Dynamic Evaluation of Mobile Robots Performing Welding Tasks

Abstract

As mobile robotic systems advance, they become viable technologies for automating manufacturing processes in fields that traditionally have not seen much automation. Such fields include shipbuilding, windmill, tank, and pipeline construction. Some of the manufacturing tasks in these fields require process validation prior to use in the manufacturing process. One such example process is welding. However, there is a lack of industry standards for mechanized or robotic welding that can impede the introduction of mobile robotic welding systems in the market place. There is also a lack of generalized fitness measures that gauge the suitability of mobile robot topologies or dimensional designs to a set of tasks and can be used in the design or verification process. This paper will consider the metrics that can be used in evaluating mobile robot designs for welding tasks based on kinematic and dynamic characteristics. The approach is based on a representation of the weld task and robot capabilities as a pair of n-dimensional subsets in the Euclidean n-space, where the weld task is considered a repetitive pattern constructed along the weld seam and both kinematic and dynamic characteristics are considered for the robot. The motivation is to allow different mobile manipulator designs to be measured using a direct geometric comparison of the capabilities of the robot to the requirements of the task. Three mobile welding platforms having different topological kinematic arrangements and will be evaluated based on this metric. This metric will further be shown to supplement the weld qualification process through verification of the motion control portions of the weld process based on a specific robot design. The method will contribute to the design and development of mobile robotic welding systems to become viable and accepted.