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Drilling is one of the most costly and labour-intensive operations in aircraft assembly. Rather than automating with expensive fixtures and precise machinery, our approach is to make use of standard low-cost robot equipment in combination with sensor feedback. The focus is to eliminate the sliding movement of the end-effector during the clamp-up, called the skating effect, and to keep the end-effector orthogonal to the surface, thus avoiding holes that are not perpendicular. To that end, force feedback is used for building up pressure to clamp up an end-effector to the work-piece surface prior to drilling. The system, including the planning of force parameters for each hole to be drilled, was programmed in DELMIA. The drilling was accomplished with the aid of an extension to the ABB Rapid language called ExtRapid, which is an XML-like code that is interpreted by the force feedback controller downstream in the process.

Automation in aerospace industry is often in the form of dedicated solutions and focused on processes like drilling, riveting etc. The common industrial robot has due to limitations in positional accuracy and stiffness often been unsuitable for aerospace manufacturing. One major cost driver in aircraft manufacturing is manual assembly and the bespoke tooling needed. Assembly tasks frequently involve setting relations between parts rather than a global need for accuracy. This makes assembly a suitable process for the use of force control. With force control a robot equipped with needed software and hardware, searches for desired force rather than for a position. To test the usefulness of force control for aircraft assembly an experimental case aligning a compliant rib to multiple surfaces was designed and executed. The system used consisted of a standard ABB robot and an open controller and the assembly sequence was made up of several steps in order to achieve final position.