Commercial delivery drones can travel at freeway speeds, up to 70 mph.
Photo: Microchip Technology

The commercial drone delivery industry is quickly gaining popularity, attracting traditional delivery service providers and startup unmanned aerial system (UAS) manufacturers. The primary obstacle for these ventures is the strict body of regulations governing production and operation in the commercial market. Designing for these criteria early is much safer and more cost-effective than conforming to regulations later in deployment. Continued adoption of commercial drones depends on field programmable gate arrays (FPGAs) that enable them to meet these regulatory requirements while also solving size, power, and reliability challenges; eliminating the risk of high-altitude radiation-related failures; and protecting against a growing range of cyber threats.

The main factors affecting drone avionics often require tradeoffs between security, processing performance, power, mass, and form factor. These can all be addressed with the latest generation of FPGAs.

Figure 1: (Above) Flash and SONOS FPGAs offer 30% to 50% less power than SRAM-based FPGAs.

FPGA solutions

Drone designers need small, power-efficient, reliable electronic components that are secure against malicious threats. Stringent power, size, and weight constraints impact battery life. In addition to these requirements, UAS are subject to harsh environments such as neutron effects, moisture, and extreme temperatures.

Like all avionics systems, those in UAS need to be as compact and as light as possible, minimizing or eliminating heatsinks. Smaller electronic components reduce the printed circuit board (PCB) and electronics enclosure size, reducing total system weight while improving efficiency, battery life, and flight time.

Flash-based and silicon-oxide – nitride-oxide-silicon (SONOS)-based FPGAs address these challenges for all drone system applications including sensor interfacing, flight control, and image processing. These types of FPGAs consume the least power – up to 50% less power than their static random-access memory (SRAM)-based counterparts (Figure 1). They remove the need for heat sinks and reduce the weight of the overall system without sacrificing total system efficiency.

Because commercial UAS avionics must meet DO-254 standards, drone manufacturers must select components with an extensive service history, necessary for certification. For aviation manufacturers, this means selecting vendors that can provide the necessary documentation and guidance for DO-254 certification.

Selecting components that are immune to configuration neutron single event upsets (SEU) is another important consideration (Figure 2). Neutron flux (neutrons per cm2 per second) increases with altitude. For example, rising 40,000ft above sea level (a typical commercial aviation flying altitude) increases neutron flux by a factor of 515. Neutron SEU could result in a device malfunction and failure, resulting in a catastrophic event if a drone breaks down and lands on a moving vehicle at high speed, or if it’s transporting vital supplies to a patient.

For drones flying in U.S. states such as Colorado, Utah, and New Mexico with a ground-level elevation close to 10,000ft, neutron effects begin to be noticeable, increasing the neutron flux 12x. Flash- and SONOS-based FPGAs are immune to radiation-induced configuration upsets and won’t lose functionality at these altitudes.

Security is another concern in aviation applications. Security starts during silicon manufacturing and continues through system deployment and operations. Flash- and SONOS-based FPGAs represent the industry’s most advanced and secure programmable FPGAs. In addition to embedded security crypto-processors, these FPGAS include key capabilities required to create a trusted and secure hardware platform for a secure embedded system, making them invulnerable to cloning, copying, and reverse engineering. Sensitive data in embedded systems is protected from malicious attacks. Some of these key capabilities not offered in SRAM-based FPGAs are secure key storage using physically unclonable function (PUF) and licensed, patent-protected differential power analysis (DPA) pass-through. Any programmable device is vulnerable to attacks, so designers need to buy electronics with security features produced by trusted manufacturers.

Figure 2: Flash and SONOS-based FPGAs are immune to single event upsets (SEUs).

Conclusion

Drone delivery today is heavily restricted by transportation authorities, primarily due to concerns for human safety and privacy. By designing drones to mitigate these concerns, manufacturers can directly influence the industry’s acceleration. Flash- and SONOS-based FPGAs enable developers to account for safety, security, and reliability throughout the design and deployment processes, while also reducing the size and cost of drones and mitigating the risk that radiation-related configuration upsets will cause them to fail at higher altitudes. These FPGA characteristics solve some of the biggest challenges that drone and electronics designers face and can be the answer to making commercial drone delivery a regular occurrence in the very near future.

Microchip Technology Inc.

About the authors: Maria Zaitchenko is a student at the University of Toronto, in the faculty of Applied Science and Engineering. She can be reached at m.zaitchenko@mail.utoronto.ca . Julian Di Matteo is senior product marketing engineer, space and aviation, Microchip. He can be reached at julian.dimatteo@microchip.com.