Wednesday, May 30, 2012

F-35 helmet’s jitter problem should be fixed by this summer

There’s been some negative press about the F-35’s next-generation helmet display, with some critics claiming it can’t be fixed and is unworkable.  That seems not to be the case.

One of the problems, jitter, should be fixed by this summer according to JSF Program Executive Officer Vice Adm. David Venlet as reported by Inside Defense (subscription required).

Vision Systems International (VSI) has identified the fix for the jitter problem:

Jitter occurs because a transmitter mounted on the F-35 pilot's seat feels the effects of aircraft vibration, and pilots generally do not move their heads in sync with that vibration, King said. The two unique movements confuse the HMDS technology and cause pilots to see shaky, unstable images on their visors.

The correction:

To correct that deficiency, King said VSI is installing a micro-inertial measurement unit (IMU) on its helmets that will dampen the vibrations on the transmitter, similar to the way noise-canceling headphones are able to block out background noise. That technology is set to be flight-tested on a JSF flight sciences test aircraft in late May or early June, and a more rigorous test involving an F-35 equipped with full mission systems software and hardware will take place in late June or July. King predicted that although those tests are unlikely to result in a perfect solution, they should illustrate what specific areas VSI needs to focus on to eliminate jitter altogether.

VSI President Philip King says:

"What I think is going to happen is we're going to find out there's a vibration component or a frequency component we weren't aware of, and we're going to have to tweak the algorithm to dampen out that last little piece," he said. "I expect it to be about 90 percent successful based on all our lab work and everything else, and the remaining 10 percent I characterize as more fine-tuning than anything else. My expectation is by the end of the summer, we're going to have this problem behind us."

The helmet also has two other issues.  Night vision:

A solution to the second major challenge on the HMDS, night vision quality, is further off, but King expressed confidence that VSI and its partners can improve the helmet camera's acuity at night from its current level of about 20/70. An F-35 test pilot told ITAF last year that the program's requirement is 20/40 vision.

According to King, the company's proposed solution is to incorporate an improved digital camera sensor from subcontractor Intevac Photonics, which in May won a $10 million contract for night vision technology production for the Army's Apache helicopter program. That new sensor will still provide somewhat inferior acuity than legacy night vision goggles, but it will be able to link up with the F-35's advanced sensors, which goggles cannot connect to.

VSI is looking at March of 2013 for that improvement to be functioning.

The third and final issue with the helmet – image latency:

The third challenge to the HMDS' functionality, image latency, demands a more collaborative approach because it requires improvements to a variety of systems on the F-35, not only the helmet. Whereas VSI is directly responsible for improving jitter and night vision acuity, it is only partially responsible for enhancing the rate at which the F-35's sensors transfer information to the HMDS, and King stressed that referring to latency as solely a helmet problem is inaccurate.

In the F-35, sensors -- some associated with Northrop Grumman's electro-optical distributed aperture system -- collect imagery and video, which is then transferred through multiple processors until it reaches the helmet. The millisecond-length delays incurred at each step of that chain add up to create an image delay problem, King explained. Through engineering test and evaluation that included some pilot involvement, Lockheed Martin determined that latency of up to 150 milliseconds is acceptable, and the portion of those 150 milliseconds directly attributable to the HMDS is about 40 milliseconds, or less than one third.

Lockheed has supplied VSI with a list of "10 or so" specifications related to different helmet operations for VSI to fulfill its portion of the latency fix process, and King said the company will be able to meet those requirements. He declined to discuss how long it might take for the JSF program to eliminate image latency, though, and deferred comment on that process to Lockheed.

It appears then, that all three issues are solvable.  Once done, they will provide an advantage to the F-35 that legacy aircraft don’t enjoy:

The most significant improvement inherent in the F-35 HMDS is that it will get rid of a key piece of hardware known as a heads-up display and instead show the information traditionally displayed on the HUD on the helmet's visor in a virtual format. Eliminating the HUD, which is bolted onto legacy airplanes, and replacing it with a "virtual HUD" should simplify sustainment, save money and provide much greater capability in the long term, King said, but the technology is far from mature.

But that’s why developmental work is so critical to our national defense future.  What we are learning here and implementing will serve future pilots with an advantage over pilots flying legacy aircraft.  It will maintain our technological edge, make our pilots more efficient and effective and, as noted, also help on the fiscal side of things.

While it isn’t a “mature” technology at this point, it is a technology which is worth the effort for the reasons stated.  Look for the first fix this summer.


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