GOALI: Enabling Friction Stir Welding in Unstructured Environments Through Process Identification and Shared Control

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

The objective of this project is to determine how well a skilled human operator can share in the control of a robotic friction stir weld system. Friction stir welding has been called the most significant advance in joining technology in the last 20 years. It offers advantages in weld quality, consistency, energy consumption, and cost over traditional joining methods, yet its introduction has been hampered by a need for significant up-front effort in developing part-specific programs for machine control. To justify these up-front investments, production volumes must be sufficient to amortize the investment at a reasonable cost per part, precluding use of friction stir welding in low-volume and repair applications. In addition, large process uncertainties such as weld path deviation and widely varying gap conditions between plates arise in many manufacturing applications but cannot be addressed using traditional control techniques. Finally, the large forces required during friction stir welding prevent it from becoming a manual process. To realize the benefits of friction stir welding for low-volume and repair applications, it is our belief, that a tele-operated robotic system, employing shared human-computer control, offers the best chance to overcome the limitations. To accomplish this and evaluate its effectiveness, we have devised a three phase research approach. Phase1 will seek to understand how specific friction stir welding process parameters, such as feed rate, travel angle, and working angle, affect the quality of a friction stir weld. Phase 2 will determine the optimal method of controlling these parameters ? through direct computer control or through a shared-human control approach. In Phase 3, we will evaluate the performance of the shared-control architecture in a lab and production environment where large aluminum assemblies are fabricated. The benefits to society include the development of an enabling technology for on-site friction stir welding - giving this emerging solid-state welding process the same flexibility that current fusion processes enjoy. In addition, societal benefits arise from the application of shared control to a variety of manufacturing processes used in repair, one-off, and low-volume production. Further societal impact will result from integrating techniques and results into the engineering curriculum and training students in this interdisciplinary research. Close industrial collaboration will enhance technology transfer and the opportunity for students to receive diverse research experience, and to successfully make connections from basic science to important technological needs.