7.0 Automation Inspection Robots

7.0 Automation Inspection Robots

When we began designing a system to automate the eddy current inspections, we discovered that there were existing automatic inspection robots in development. The systems, sponsored by a variety of establishments including the FAA, Air Force, State of Pennsylvania, Boeing, private entrepreneurs, range in ability and focus. US Airways and Northwest Airlines accommodate these systems. This report describes several of the robots.

7.1 WichitaState’s Rostam

Students and professors at WichitaStateUniversity in Kansas probably were the first to create robots for automated aircraft skin inspection. The wall-climbing robot, Rostam, incorporates the use of one large suction cup on a “belly” and two smaller suction cups on each of two legs. The robot has a vision system for automated crack monitoring and guidance. Although Rostam is extremely innovative, it has never been able to produce any reliable data [16].

Rostam is displayed in Figure 4.

Figure 4. Rostam on aircraft material [16]

7.2 Tektrend’s PANDA®

NDT techniques do not always produce complete measurement evaluations because of incomplete operating ranges. The use of multiple techniques has numerous advantages including reduction in inspection time, increased reliability, improved defect visualization, and redundancy. Tektrend has designed a modular and portable system that incorporates several NDT methods into one device to provide quick automated scanning of aircrafts [17].

One can configure the system for conventional ultrasonic, guided wave and eddy current testing. In addition, implementation and installation of Edge of Light (EOL) sensor on the system is currently under development [17].

In testing of the PANDA® system, guided wave and edge of light techniques were relatively fast compared to the eddy current and ultrasonic testing [17]. Because the system accomplishes tasks beyond simple eddy current testing, it is not feasible to alter it to determine the difference between alodined and anodized rivets. In addition, while the system can adjust to various curvatures, it is not rotationally mobile and must be repositioned by inspectors often during operation [17].

Figure 5 shows the PANDA system.

Figure 5. PANDA Inspection System [17]

7.3 Autocrawler

A Seattle-based company, called Autocrawler LLC, is collaborating with Boeing and the Air Force to develop a suction-cupped tank-like system to allow simultaneous exterior aircraft cleaning while performing inspections for rivet hole cracks [16]. The robot features powerful air motors and high capacity vacuum ejectors that allow it to carry heavy loads at high speeds [status and prospects]. The system contains an eddy current array sensor, magneto-optic imager, a vision sensor to assist the operator in following seams and rivet lines, and an infrared-light pulse tracker to provide positioning of the robot. Tests demonstrate that the system can cover five inches per second. [18]. The speed of the Autocrawler makes inspections abide to our requirements. However, the machine produces a large amount of noise and is known to scuff aluminum. The Autocrawler is shown in Figure 6.

Figure 6. Autocrawler on the side of an aircraft [16]

7.4 Vanderbilt’s ROBotic INspector (ROBIN)

VanderbiltUniversity’s ROBIN is intended to be the basic component of a larger structural inspection system [19]. The system is basically two rods connected by a hinge, with two suction cups at the two free ends, and pneumatic actuators that allow it to walk [16]. ROBIN’s innovative design resembles a walking leg with muscles and exhibits four degrees of freedom mobility. The robot is able to step over obstacles in its path, transfer itself from a horizontal to vertical surface and back, walk forward, walk backward and turn in place [19

ROBIN does not currently include testing devices [16]. However, engineers can easily adapt the system to carry an eddy current probe on its feet.

Figures 7a and 7b show ROBIN.

Figure 7a. ROBIN on Table [19] Figure 7b. ROBIN Climbing Wall [19]

7.5 JPL’s Multifunction Automated Crawling System (MACS)

JPL recently developed Multifunction Automated Crawling System (MACS), a dexterous and compact aircraft crawler with a payload to weight ratio of approximately 10:1 that performs complex scanning tasks [20]. The structure of MACS includes ultrasonic motors for mobility, suction cups that alternate attachment and detachment for surface adherence, and two legs for linear motion, one of which also facilitates rotational movement. The highly-mobile system can inspect for cracks, corrosion, impact damage, separations, delaminations, fire damage, porosity and paint thickness of composite and metallic structures. MACS can also detect dents and fasteners [21].

Database, analytical tools, CAD drawing, and accept/reject criteria tools for rapid responses to emergency inspections of large fleets during idle time allow remote operation of MACS [20]. Like Tektrend’s PANDA, MACS combines several NDT techniques, including visual, eddy current and ultrasonic technology [20].

Future efforts are underway to increase the independence and capabilities of MACS. These efforts include the creation of a completely wireless communication system and the use of Global Positioning Systems (GPS) to determine the absolute coordinates without encoders [21]. Simulating GPS signals indoor is currenty costly and complicated but is expected to allow for increased positioning accuracy in the future [22]. In addition, engineers are working to install a miniature on-board vacuum pump, power, computing capability, and a virtual vision system into MACS [16].

The future of the system is unknown due to internal changes within JPL [16]. However, if the project is continued, it is expected to be an excellent resource for aircraft maintenance.

Figure 8 displays MACS.

Figure 8. JPL’s Multifunction Automated Crawling System (MACS) [20]

7.6 Carnegie Mellon’s Automated Non-Destructive Inspector (ANDI)

Researchers at Carnegie Mellon University (CMU) were the first to develop a fully- automated ultrasonic and eddy current aircraft rivet-wing inspection system using a multi-axis robot and a dripless bubbler system that is able to test almost any surface of any contour [16]. The Automatic Non-Destructive Inspector (ANDI) is described in detail in Section 8.0