Microsoft HoloLens 2 elevating 3D metrology
One of the biggest technological advancements in 3D metrology was the invention of laser trackers. Not only could they provide high levels of accuracy over large measurement ranges, but they were the solution of choice in the aerospace, ground transportation, energy and naval manufacturing industries.
However, with limitations including the need for two operators, using a mobile phone for remote control, and the geometries of measured pieces being displayed on external projectors, manufacturers are looking for alternative means to complete their measurements.
But the solution to these issues may already be upon us. Mixed reality technologies, like Microsoft’s HoloLens 2, feature a holographic display, tracking systems, cameras, a 3D scanner, and software that when paired with the PolyWorks|AR app can provide enhanced performance when it comes to large-scale measurements.
The limitations experienced when using laser trackers are a thing of the past for mixed reality technologies. External projectors are no longer needed, operators can work hands-free, switching between inspection tasks is easier, and there is a smaller chance of operators measuring incorrect parts.
Issues faced when measuring before and after the introduction of laser trackers
Depending on the size of the object the operators were tasked to measure, the number of issues they would experience could vary massively. Before the introduction of laser trackers, these problems would include:
- Measuring objects smaller than two metres: This would be a straightforward process as the operators would easily be able to compare the real-life object and the scan on the display. They would also be able to quickly return to the computer to interact with any 3D measurement software.
- Measuring objects larger than five metres: The potential for inaccuracies creep in at this size. Operators may experience issues with their positioning and distinguishing measurement targets, comparing real-life and computer data also becomes more difficult, and walking between the measured object and the computer also becomes longer, wasting valuable time.
Following the introduction of laser trackers, some of these issues were alleviated. Two operators were now on the scene, one performing the measurements with the second stationed at the computer. While this worked to minimise the amount of time it would take to complete 3D measurements, needing two operators to complete one task was not cost-effective.
Additionally, the task given to the operator at the computer station was difficult, as they needed to maintain fixed eye contact on the screen while moving with the assembly. The difficulty of this task made it more likely that errors could occur.
Improvements made to the laser tracker measuring process
While the introduction of laser trackers was successful, the solution did not get rid of all issues. Instead, operators went on to receive two further developments to help ease any remaining issues.
The first of these were projection technologies. Using either a laser beam or an area-based projector, these solutions could project guidance geometry and measurement results on the surface of the measured objects. This allowed for the analysis of measurement results to occur quickly.
However, projectors were difficult and constraining, primarily because they could only reach surfaces visible to them. If the operator wanted to reach more areas, they would have to move the projector to multiple locations which would be time-consuming.
The introduction of mobile phones also transformed large-scale measurement tasks as they allowed remote control. This made the matching and comparison of real-life measurements and computer data easier, with visual guidance and measurement results now accessible. Additionally, measurements could be completed quicker, and with only one operator.
However, most mobile phones lack the sensors to measure their orientation in 3D spaces. The phone needed to be close to the object for the screen to display properly, and the operator also needed to carry the mobile phone during the scanning process. The latter makes climbing ladders and other objects almost impossible.
Mixed reality is the next step in 3D measurement
Now, with the development of mixed reality technologies, solutions like the Microsoft HoloLens 2 provide the services of the technologies we’ve previously mentioned, without the same limitations. The main advantages of the HoloLens 2 include:
- The ability to track changes in position and orientation (6 degrees of freedom).
- Track eye movements.
- With holographic projection, graphical information can be projected on measured parts once the device is localised.
- Hand gestures are recognised by several cameras and software.
- The surrounding area of the measured object will also be scanned.
By using the HoloLens 2 for 3D measurements, the operator will receive geometries projected on measured pieces for easier analysis, with no shadow areas. There is also no need for a fixed set-up, which allows the operator to move quickly through the scanning process. The headset is also hands-free, which is safer for the operator.
Microsoft HoloLens 2 in action
While mixed reality technologies also fulfil previous limitations in this area, the solution also brings technological innovations to 3D measurements. With the operator’s viewpoint and position now known, lost laser-tracker beams are now easier to redirect. Changing operator location is easier, with no fixed set-up, and creating a 3D point in a specific area can now be done with the operator’s head or eyes. Additionally, the user can also manipulate 3D geometries with their hands. This can also make the aligning of reality and mixed reality images and holograms easier to trace.