Design News, April 2013

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Automation & Control Robot manufacturers and integrators are developing new ways to integrate those requirements. Source: FANUC Robotics Sealing and Dispensing Blanchette said there are a series of different trends and developments that are driving robotics industry manufacturing technology for aerospace and defense applications. For the past two years, drilling and fastening were the fastest growing application areas using robotics automation. But now the trend has shifted to sealing and dispensing. "What the aerospace companies are looking to do is eliminate manual processes that take a lot of production time," said Blanchette. "One challenge is that the designs are using materials which have a very short usable life, especially in applications such as sealing wings that are also full of fuel." The primary goal for the automation is to save time of time to be dispensed. Blanchette said there is research on new automated cartridge dispensing methods and new materials using robotics, while also looking at mixing materials on demand, as they are needed. One example of a sealing operation is an aircraft wing assembly, where under the skin of the aircraft there are spars that provide structural integrity. The spars are used to attach the wing to the wing box. All of the connection points and fasteners on the wings that are exposed to the outside need to be sealed to prevent corrosion and leaking since the wings are filled with fuel. Robotic Force Sensor Feedback "What we're hearing from aerospace customers is that they want robots to get smarter. One way that is happening is by mounting force sensors on the end effectors which provides on-the-fly feedback to the robot controller," Chris Kolb of Aerobotix Inc. said. "This technology is now allowing the robot to change its original path in real time based on the force sensor feedback." Kolb said it's now possible to take a sanding path for a known part, teach the path to a robot, and specify 1.6 kilograms of pressure on the sanding pad while operating. If the tooling changes or the part is moving, the application has a way to "fix" the path. "With the force sensor in the system looking for the 1.6 kilograms of pressure, the robot will automatically adjust to a flat wing that is in a horizontal presentation, for example, and seek down in the Z-axis to find that 1.6 kilograms while it is running the baseline path," Kolb said. "To have the robot changing its kinematic Robots are now using secondary encoders to very accurately drive positionpath on-the-fly to achieve a process set point is ing of a drill, using the feedback similar to the way a machine tool operates incredible." to pinpoint the position of each joint for more accurate, repeatable drilling In the past, Kolb said the end effector might performance. have used pneumatics to press down at a certain psi. The cylinders would use extra stroke to because of throughput issues, as aerospace manufacturers are compensate if the part fell away from the program, and the finding that demand is exceeding their ability to produce. end effector would have enough compliance to seek the part. In order to increase capacity using the same manufacturBut with the force sensor end effector, the robot itself is ing methods used in the past, there would be a requirement seeking contact with the part and finely adjusting to mainto add real estate to the production facility and the space tain a set point within a couple tenths of a kilogram. The required for these operations would be quite large. Since end result is increased application in tooling and parts by it is difficult to be globally competitive using this model, not needing a large number of programs, touch-offs, and manufacturers are looking to automate some of these proframe shifts to locate the part in the robotic workspace. cesses that are holding up production rates. "We have used this technology in sanding applications Sealing has become a main application area because it but there we see other processes like sanding or grinding demands a lot of manpower to encapsulate the spars and using this technology to allow the robot to 'feel' the process fasteners, and the materials in use don't offer a long period and adjust like a human. But for the robot to change its Design News | april 2013 | www.d esign n –44–

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