Since robotic work cells have proven to be highly effective in certain applications, and the technology is always improving, some might dream of a day when aircraft can be made like cars on heavily automated assembly lines with all the associated benefits.
Boeing has made an advance in that direction.
Robotic workcells are only able to achieve consistent quality because everything in them is highly controlled; every aspect of the operation is carefully planned and tested and every workplace must conform to a strict set of tolerances to ensure quality. Luckily, there is an alternative: the fully autonomous robotic system.
In the fully autonomous robotic system, the robot is freed from the cell and equipped with a vast array of sensors. It can move about a large structure, identify reference points, and perform operations on an un-fixtured workpiece. The only problem with this scenario is the astronomically high cost of develop-ing such a system—including a highly technical workforce required to maintain it.
According to researchers at Boeing and Novator AB, the smart portable tool is, at its core, indistinguishable from a fully autonomous robotic system in that a complex end effecter is used to perform operation with high consistency while it is being positioned by a hyper-capable entity; the only difference with a smart portable tool is that the entity is a human, not a super-expensive imaginary robot.
The benefits of robotic systems are clear, but as with any complex system there is always the risk of protracted breakdowns due to a complex problem. Since robotic systems are usually implemented at critical manufacturing flow points, a breakdown can cause a stop in production. The effect of a machine breakdown must be considered when designing a process. The best insurance is redundancy, but it might be difficult to justify buying a spare robot. In the case of a smart portable tool such as a portable orbital drill motor, the cost of a spare is not prohibitive and any unit can perform the task of any other like unit—meaning that so long as one motor is functioning the job gets done.
Another limiting factor to the robotic workcell or even a fully autonomous robotic system is the lack of versatility. The main challenge of a robotic application is creating a robust process. In general this involves developing a highly specialized process capable of performing one job very well. In aircraft final assembly, the variety of jobs is great and necessitates the development of many unique solutions. Robotic systems designed for one task might be useless on the next task and would undoubtedly need to be replaced or upgraded every time a design change is implemented on the structure. The world’s scrap yards are filled with yesterday’s specialized tools, but every factory is equipped with general tools that have remained unchanged for decades. Tool obsolescence is the enemy of agile assembly; tooling up for a new design should be a matter of adaptation, not invention.
The practical solution to increase the efficiency in final assembly is evolving via the development of smart portable tools. Workers are at their most efficient when all information is available, no decisions are required, and the risk of making mistakes is reduced. With today’s information technologies inte-grated into the portable tools, all of these issues can be addressed.
This capability to have the process knowledge built into the portable tool allows the positioning system (the human) to perform multiple activities within the work area of the final assembly. It also stabilizes the assembly process by enabling the skilled mechanics to cover for team members who may have an unplanned absence or might just be stepping out for a minute.
Boeing has traveled far down this path by introducing smart portable tool technologies for orbital drilling in the wing-to-body join of its 787 Dreamliner.
Tapping into the depth of resources across the corporation, the company found a technology from Sweden (Novator AB) being developed in California that could supply a solution for their assembly lines in Washington state. With the “One Boeing” philosophy, they were able to create a team that worked together to address all concerns of hole quality, manufacturing costs, equipment reliability, production support, and logistics.
Production mechanics and motor setup technicians were brought in at an early stage to help design the layout of the workcell. All input was used to develop the most efficient sequencing of the work to maximize productivity. With the use of simulation software and workcell mockups, the mechanics were completely familiar with the equipment and the new work sequencing before the first airplane was drilled.
The efficiency of the process is built into the smart motor’s programs, thus scaling up production rates by bringing in new mechanics for a second assembly line proved to be painless. The speed at which a technology can be expanded with the resulting increase in productivity proves the smart portable tool philosophy to be the right approach to take for today’s aircraft and all final assembly lines going forward.
The article is based on SAE International technical paper 2013-01-2295 by Wesley Holleman and Eric Whinnem of Boeing Research & Technology; and Madeleine Wrede of Novator AB.