Portable Laser-Guided Robotic Metrology (PLGRM)
Instrumentation
Portable Laser-Guided Robotic Metrology (PLGRM) (LEW-TOPS-165)
Inexpensive & accurate method for testing antennas
Overview
Antennas are used in many industries and products where quality and reliability are crucial. Testing aircraft antennas is challenging since optimal tests are made after antenna installation. Aircraft are often taken to anechoic antenna test facilities which create long lead times, transportation hassle, and very high costs. This makes such testing cost-prohibitive for early R&D work. Portable alternatives exist but often have compromised testing fidelity.
Innovators at the NASA Glenn Research Center (GRC) have developed the PLGRM system which allows an installed antenna to be characterized in an aircraft hangar. All PLGRM components can be packed onto pallets, shipped, and easily operated. The flexibility and portability of this system while maintaining precision and accuracy are what make PLGRM unique. While developed for aerospace, PLGRM can be used to characterize antenna systems across a range of applications. Extending applications beyond just antenna analysis may also be possible.
The Technology
The PLGRM system is designed for in-situ antenna measurements at a remote site. Components include a collaborative (i.e., certified to operate in close proximity with humans) robot arm mounted on a vertical lift and a laser tracker, each on a mobile base. Together, these components enable scanning of a surface larger than the reach of the robot. To accomplish this, the robot first collects all points within its reach, then the system is moved and the laser tracker is used to relocate the robot before additional points are captured.
Safety, collision avoidance, and planning aspects are combined to effectively characterize such antennas. Software-defined triggering is also a feature for flexible integration of network analyzers and antenna controllers. Laser tracking is used over photogrammetry to provide position feedback with higher speed and lower latency that facilitates online control of the robotic arm. While collecting the antenna radiation data, the system uses pulsed measurements and time gating to remove unwanted reflections. This lowers the requirement for fully surrounding the test area in anechoic foam. The system also accommodates the possibility of "dirty power" that may be found at any given host facility.
NASA has published data that demonstrate system functionality and accuracy. See the PLGRM presentation and paper from the 2019 Antenna Measurement Techniques Association Symposium (AMTA) for more details on component choices, portability challenges, implementation, and measurement data.


Benefits
- Portable: Rather than moving an aircraft to an expensive test facility, PLGRM can be shipped to an aircraft location – saving much time, money, and hassle.
- Easy to use: PLGRM can be deployed by only two people and can be powered by standard 110-volt wall outlets – making it simple to implement.
- Flexible: PLGRM can scan an arbitrary surface geometry, accommodate different scan sizes, facilitate both near-field and far-field scans, and can test antennas that are visible or covered by a radome – meaning measurement quality is not compromised.
Applications
- Aerospace
- Defense
- Telecommunications
- Automotive
- Research & Development
Technology Details
Instrumentation
LEW-TOPS-165
LEW-19895-1
P. A. Slater, J. M. Downey, M. T. Piasecki and B. L. Schoenholz, "Portable Laser Guided Robotic Metrology System," 2019 Antenna Measurement Techniques Association Symposium (AMTA), 2019, pp. 1-6, doi: 10.23919/AMTAP.2019.8906337
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