QMT Features: September 2008
Laser radar in its sights
Janicki Industries utilizes laser radar measurement technology to develop innovative composite tooling for large-scale lightweight prototype aircraft parts


Janicki Industries, based in Sedro-Woolley, Washington, USA, produces high-precision advanced composite tools and excels at designing and fabricating large complex composite tooling.

The company’s (pole) models, test equipment and full-size metallic and composite structures are typically used as prototypes for aerodynamic property testing, radar testing or for any other customer requirement. Today, tooling expertise developed at Janicki serves the majority of international aircraft OEMs as well as manufacturers of boats, motor homes, buses and monorails. The company has a growing involvement in tooling development for composite wind turbine blades, and occasionally participates in special projects, such as prototyping speedy racing yachts that compete in the renowned America’s Cup.

When developing new tooling concepts for large prototype structures, Janicki faces short turnaround times and high-precision requirements. As a result, the company’s metrology specialists are fully occupied with systematic quality verification of structural assemblies being developed. “To meet the growing demand for tighter timing deadlines in developing large aircraft fuselage sections, our metrology team opted for three Metris Laser Radar systems to validate OEMs’ geometric requirements,” John Janicki, vice president of Janicki Industries, stated. “Deciding factors were that the laser radars operate without spherically-mounted retro-reflectors (SMRs) or remote devices, and reliably deal with composite surfaces and sharp scanning angles. In automatic mode, we only need a single operator who defines and supervises scanning jobs. ”

During operation, the Metris Laser Radar directs an infrared laser beam and processes the reflected light. Janicki purchased two Metris MV260 systems that cover a 60 meter radius, and one Metris MV224 with a 24 meter reach. On the basis of accurate (fibre) optics technology and beam angle specification, the laser radar is able to accurately determine the 3D coordinates of the surface point being inspected. The technical concept of the laser radar implies that measurement accuracy depends on the length of the laser beam: 0.016 mm at 1 m distance; 0.1 mm at 10 m and 0.24 mm at 24 m.

Capturing only a very small fraction of the reflected laser beam is sufficient to make a valid measurement, thanks to the system’s innovative frequency modulation laser technology. As a result, the Metris Laser Radar, unlike laser trackers, can operate in any lighting conditions and on any surface with a reflectivity of one percent or more. Using Metris’ high-quality optical flat mirrors, the laser radar can additionally access surfaces that are otherwise unreachable. “Non-contact in combination with large scale is the most important asset of the laser radar solution,” said Michael Batchelor, metrology manager at Janicki Industries. “Although Metris Laser Radar is high-tech equipment, its use is quite straightforward. The laser radar unit is able to measure any surface point you can see within the measurement envelope of the system. The rugged industrial laser radar proved itself in our harsh composite milling environment as well as at remote outdoor locations.”

Giant fuselage section scanned
Nearly 6 meter in diameter and about 12 meters in length is the size of an all-composite fuselage section that has been developed for a new groundbreaking composite superliner aircraft. Janicki’s metrology engineers used Metris Laser Radars to accurately measure the detailed geometry of this immense fuselage section as well as an individual 60 degree section subassembly. As the Metris Laser Radar is able to gather data over extremely large areas in a contiguous coordinate system, the system can be positioned successively at multiple positions without requiring complicated reassembly of geometry point data clouds. This is achieved by scanning fixed tooling balls that allow the laser radar to determine its own new position relative to the fuselage section.

Janicki engineers positioned the laser radar at 10 unique positions to cover all interior and exterior surfaces of the entire fuselage section. For the subsection assembly, 5 positions were sufficient. After gathering geometry data in uniform scans, they exported the digital model to third-party software for further numerical and graphical geometry assessment. In this case, they responded to OEM-defined requirements by delivering a point file along with a geometry verification report including point deviation data and information regarding critical features.

The laser radar is a single operator measurement solution. Visible from behind the mobile workstation of the laser radar, the operator can point a clear large-dot laser to any desired point on the structure. This red dot clearly marks the approximate location of the invisible measuring beam of the laser radar. Based on imported fuselage CAD data, a Janicki metrology engineer specifies the scanning area by driving the red dot around the perimeter of the fuselage section. After defining the point density, the system scans the area in automatic mode. After acquiring the 3D coordinates of one point, the laser radar beam automatically redirects to the next point. The total time to complete a point pattern scan is in the order of minutes. The laser radar also supports manual point measurements, which can be recorded on command by steering the beam to the required surface location.

Following this scanning approach, Janicki metrology engineers are able to accurately measure the large-scale fuselage surface, without requiring photogrammetry dots, SMRs, probes or other remote devices. Compared to laser tracker equipment, where one person operates the tracker and the other one holds the device, the Metris Laser Radar system can be operated by a single person. This eliminates a second operator, who would otherwise need to physically access the many measurement locations on the concave surfaces of the fuselage structure. “Overall, when considering non-contact laser scanning in automatic mode, we succeeded in increasing geometry verification productivity by a factor of 5,” stated Michael Batchelor. “At the same time, the accuracy of the laser radar meets or exceeds our customers’ precision requirements. Besides high accuracy, the laser radar guarantees high measurement repeatability, which allows us to confidently perform direct point-to-point measurements.”

Large-scale accuracy is a real challenge, especially since Janicki becomes increasingly involved in tooling projects for very large composite parts. Over the years, the company’s growing internal metrology group gained top metrology expertise and has innovate measurement equipment in house, including the three laser radar systems from Metris. The combination of specialized metrology expertise and market leading equipment speed up geometry verification to help meet tighter tooling project deadlines, and offers great opportunity to explore new business through metrology outsourcing projects.

Originally, Janicki focused on developing CNC milling machines that convert CAD files into plugs, patterns, molds and prototypes parts for large items. As an innovation company that systematically searches for new emerging technologies, Janicki recognizes the potential of utilizing Metris Laser Radar as part of large gantry mounted drilling machines. In this case, the laser radar would provide independent adaptive positioning control of the drilling head, which in itself would drastically reduce the cost of the positioning overhead of these massive machines. The enabling metrology technology of the Metris Laser Radar would enable Janicki to design and build cost effective automated milling equipment to accommodate even larger composite parts to produce.
www.metris.com

 

  
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