UAVs: the ever-present eye in the sky

Commercial and defence UAVs are taking on new applications that require more functionality to meet these needs. Whether it's a tethered drone, a vertical take-off and landing (VTOL) drone, or a high-altitude long-endurance (HALE) drone, UAV developers are looking for ways to achieve highly efficient, lightweight, and compact power solutions.

Electronic Specifier spoke to Joe Dussi, Senior Regional Marketing Manager, North America, Vicor about some of these new applications, as well as the design considerations needed to help maximise efficiency, make them crash-proof and help prevent hacks.

What role do tethered UAVs have in today’s wireless communications landscape, especially when it comes to emergency response and natural disasters?

More emergency response service organisations and federal disaster agencies are turning to tethered drones to establish an immediate and reliable communications hub to help coordinate relief efforts as quickly as possible. Like in any large-scale relief effort, accurate and timely communications is vital to the success of any operation. Tethered drones can be dispatched and deployed quickly with relative ease and cost. They allow for communications over long distances because of the altitude they can maintain, and, in many cases, they can stay aloft for days since they are connected to a constant power source on the ground.

To make things even more flexible, the ground-based power source can be loaded onto a pick-up truck and driven to other locations with the drone in tow without creating a lapse in communication. A prime example of this is the Fukaden tethered drone system which was specifically designed to create fast and reliable wireless communications for first responders.

Can drones be used effectively to create a secure perimeter for installations like airports, ports, and other critical infrastructure?

Drones have become the ever-present eye in the sky. You can’t see them, but they are always watching. Drones have proven to be very effective at maintaining secure perimeters because of their manoeuvrability, versatility, and low profile.

Tethered drones are best suited for this task because of their ability to stay in the air for days on end. These aerial sentinels can be controlled and monitored from a central location. Depending on the mission these drones can be outfitted with an assortment of sensors including thermal, infrared, optical zoom, motion, and others to detect unauthorised entry. In some cases, these drones can be configured to neutralise a threat if deemed necessary.

How can UAVs be managed to prevent ‘drone sighting chaos’ similar to the situation at Gatwick Airport, London, in December 2018?

Unfortunately, this is an all-too-common occurrence in today’s busy international airports. One solution is to pit drone against drone. Rather than relying on human sightings alone, which are more error prone, you can employ tethered drones that are strategically positioned in the target airspace and create and overlapping grid. When an unauthorised drone enters the “no-drone” zone the other tethered drones identify, catalogue, and triangulate its position transmitting the data real-time to security for immediate response. I suppose this is what they mean when they say, “fighting fire with fire”.

What are some of the uses for VTOL UAVs in defence?

Vertical take-off and landing (VTOL) technology was first developed for defence applications. Helicopters are obvious early examples of this technology. However, as technology has evolved this functionality has become ubiquitous across many platforms including the Harrier, F-35, Osprey and yes, drones. Having the ability to take-off and land in a confined or remote area provides many advantages. As it relates to UAVs, they are very portable and can be carried by a single war fighter in many cases. They can be used for a myriad of applications including reconnaissance, security, supply delivery, targeting, loitering munition and communications. The lightweight and versatile systems have become an integral part of any battlefield strategy.

How can designers of UAVs engineer-in safety features? What design considerations are there to help prevent hacks? Or make them crash-proof?

Drones, like any other remotely operated device or system, can be susceptible to unwanted intrusion. In today’s digital age it is paramount to ensure the safety and integrity of the UAV by introducing counter measures to mitigate those risks. This can be achieved in a multilayer approach consisting of both hardware encryption and software. The safety aspect can also be enhanced with features like collision avoidance using redundant sensors to adapt to varying environmental conditions like light, temperature, vibration, wind, etc. However, there is a price to pay by adding additional sensors and cameras in the form of weight, size and power consumption. By adding more features, weight, and size you take away from your overall power budget which translates into shorter flight times and less payload capacity. The way to overcome this imbalance is to design your UAV with a power delivery network that offers high efficiency, flexibility, scalability and offers high power density, maximising the available on-board power budget.

If tethered drones are powered from a ground-based power terminal, why do power density and efficiency matter?

At first blush you would say, I have an unlimited power supply so who cares about that stuff? Taking a closer look, it’s in your best interest to design tethered UAVs with the highest power density possible and highest efficiency because that impacts your overall payload capacity.

When designing a tethered drone, it is vitally important to consider the length, diameter, and overall weight of the tether. The heavier the tether the more power you need to keep it in the air. Both power density and efficiency impact the overall size and weight of your tether. In the best-case scenario, you would want to supply the highest voltage possible to supply your power delivery network that allows you to compensate for the higher losses for the lighter cabling. By doing this you can carry heavier payloads at higher altitudes making the UAV more versatile.