Advances in Fiber Optic Sensing Opens Door to Enhanced State Awareness and More Predictive Maintenance

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Fiber optic sensing
Chief Warrant Officer 4 Joel Sizelove, the production control officer in charge for Task Force Lift, checks the readouts from the integrated vehicle health management system on a UH-60M Black Hawk to determine, among other things, track vibrations in the rotors. (Photo by Jennifer Andersson)

When it comes to military aircraft, vehicles, and weapons systems, readiness is essential. These vital platforms and vehicles are useless if they’re not mission-ready. This makes keeping them maintained and sustained a top priority for the U.S. Department of Defense (DoD).

However, despite how much proactive maintenance is done to a military vehicle or weapons system, continued use and resulting “wear and tear” will eventually take its toll. Parts will fail, functionality will be lost, and the vehicle will need to be taken out of service for repair. And the requirement to take a vehicle out of service to repair or replace parts – like an aircraft’s landing gear or replacing a rotor blade – will invariably happen at the absolute worst time.

But what if a platform’s parts and systems could be continuously monitored to determine their condition and function? Where the health state of a component or structure could be actively monitored for strain, impact, and potential damage? What if we could monitor systems like landing gear that are prone to significant impact, wear, and tear, to see what usage they’re being subjected to? And what if we could study that data to determine how much time, distance, or pressure a system or device could withstand before starting to fail or malfunction?

New advancements in sensing technologies are opening the door to lighter, smaller, and less power-hungry sensors that could make the monitoring of individual vehicle parts a possibility – and make proactive maintenance and repair a reality.

If those things were possible, the military could get a true understanding of how much punishment systems like landing gear could take before they failed. They could track how much time, distance, and pressure an aircraft’s landing gear has experienced. They could then replace that landing gear proactively – at an optimal time and location – when taking the aircraft out of service wouldn’t negatively impact military operations.

This might sound futuristic, but it’s not.

New advancements in sensing technologies are opening the door to lighter, smaller, and less power-hungry sensors that could make the monitoring of individual vehicle parts a possibility – and make proactive maintenance and repair a reality. And the advent of fiber optic sensing is partly responsible.

Less interference, lower SWaP
Traditionally, the sensors on military vehicles – including military aircraft – have been electronic. These systems leverage transducers that create electrical signals or impulses that are then transmitted and interpreted. But these electronic sensors have not been without their faults and flaws – especially when used for military applications.

Since electrical signals are prone to interference, the electronic sensors used by the military have to be engineered at great cost and effort to make them immune to interference. And there are multiple different sources of interference on the battlefield – from electromagnetic interference (EMI) from lightning storms and communications to electromagnetic pulses (EMPs) that are created by nature or adversaries.

These electronic sensors also come with a significant burden. Their physical size, weight, and the amount of power that they require means that they need to be utilized sparingly. This is especially true for manned and unmanned aircraft, when reducing size, weight, and power (SWaP) requirements is essential.

The emergence of fiber optic sensing opens the door for the military and its industry partners to drastically increase the number of sensors that are integrated into vehicles and aircraft without the traditional burden.

Because of these factors, the military and their industry partners have shied away from integrating more sensors into many of the different systems and devices that comprise aircraft and other vehicles. Adding too many would be impractical, increase weight, require too much power, and otherwise impact vehicle performance.

But what if size, weight, and power were negligible in the SWaP equation? What would enhanced vehicle state awareness look like?

Fiber optic sensing eliminates many of these challenges. Fiber optic sensors leverage light, not electrical signals, to gauge and transmit information – using photons instead of electrons. This makes the sensors immune to electrical interference – regardless of whether it’s natural or intentionally caused by an adversary. These sensors are also smaller, lighter, and require far less power to operate.

The emergence of fiber optic sensing opens the door for the military and its industry partners to drastically increase the number of sensors that are integrated into vehicles and aircraft without the traditional burden. This means that systems and devices within the aircraft that may not have been closely monitored with sensors – like landing gear and other systems – can now be watched more closely through integrated fiber optic sensors which can monitor the state and condition of components and structures. And that could generate a number of useful benefits for the military when you need to know if an asset is ready for the mission.

Tossing out the manual
The first benefit of fiber optic sensors is the depth of specific state information that the military has for components and systems on their vehicles and aircraft. This enables increased intelligence and autonomy into the health of the disparate systems and components of these vehicles. With the state and condition now known, the military can make more proactive, more preventative maintenance decisions – fixing and repairing parts and systems before they fail and create a problem.

That is a massive benefit that will have significant repercussions on military readiness and the survivability of the warfighter. But it’s just one of many benefits that fiber optic sensors and an increase in sensor data will deliver. Another involves the automation of previously manual processes.

While proactive, and predictive maintenance might seem futuristic to many, its only real prerequisite is the ability to know the health state and usage of components and systems.

When it comes to military aircraft, knowing things like loading, balance, cargo weight, and the aircraft’s center of gravity can have a significant operational and mission impact. These factors can influence an aircraft’s performance and flight response. They can also increase the amount of stress and strain on the airframe and structures.

Historically, measurements like cargo weight, load balance, and center of gravity were identified manually by leveraging stand-alone measurements. This took time and made the measurements susceptible to human error. Should those calculations be ignored to expedite the mission, or should they be done incorrectly, the aircraft could perform less than optimally, risk damage to the aircraft, or cause loss of life. It could also sustain significant damage that could impact its mission readiness in the future.

The proliferation of sensors thanks to advancements in fiber optic sensing eliminates these manual processes, measurements, and calculations. With lighter weight and less power-hungry sensors, the military can equip aircraft with sensors designed to gauge cargo load, load balancing, and even identify the aircraft’s center of gravity automatically. This expedites the mission and eliminates the potential for human error.

While proactive, and predictive maintenance might seem futuristic to many, its only real prerequisite is the ability to know the health state and usage of components and systems. The proliferation of sensors across vehicles and aircraft – integrating them into disparate systems and devices – delivers the state awareness that the military needs to gain more actionable insights into the health of their vehicles. Fiber optic sensing is making the proliferation of sensors possible today and will make predictive maintenance a reality in the not-too-distant future.