Amazon Prime Air is the unmanned aerial vehicle (UAV) express service being tested in some regions by Amazon. Specially designed for express delivery service, this kind of UAV adopts the advanced "detect and avoid collision" technology, which allows the UAV flying at the altitude of less than 120 meters in a highly automated operation mode.  The UAV has to be designed to safely deliver a parcel of maximum 2.3kg to a customer’s place within 30 minutes, in a service area within 16 kilometers.

Figure 1: One of the UAV models used by Amazon Prime Air service (Source: Amazon)

 

Market forecast for civilian UAVs

Whether it Amazon's professional express UAV or DJI's consumer entertainment drones, the UAVs we’re talking about are just a segment of the broad UAV market. According to the UAV statistics from market research firm Tractica, globally, the number of UAVs will grow from about 80,000 today to 2.7 million in 2025, with the annual sales up to $8.2 billion. According to the data from Qianzhan Industrial Research Institute, except military UAVs, the market size of China's civilian UAV market alone will exceed 10 billion yuan RMB in 2018, which is expected to increase to 60 billion yuan RMB by 2020 and reach 180 billion yuan by 2025.

 

What is SWaP?

The rapid growth of the UAV market is driving the development of UAV materials and avionics technologies. The electronic part of the UAV design involves computing, communications, sensing, imaging, power management, etc. Regardless of the technical solution adopted, UAV design must meet the challenge of SWaP, which stands for Size, Weight and Power. It is an important factor to consider in UAV design. This paper will discuss the methods to deal with SWaP challenge from the technical perspective of microprocessor, sensor, RF and microwave device and power supply.

 

SWaP’s first challenge: System-on-Module (SOM)

In addition to computational processing performance and network communication capabilities, UAV design also has stringent requirements for the stability and security of core processor systems. As a common embedded computing platform, NXP QorIQ series of communication processors have been proven to meet these requirements. QorIQ microprocessors include the T series based on the 64-bit e5500 Power Architecture processor core and the Layerscape series based on the ARM cortexa72 core, which is especially suitable for low-power, high-processing capabilities hybrid control and data applications such as switches, routers and Internet access devices. Additionally, Teledyne e2v new Common Computing Platform Solution, called Qormino, integrating powerful PowerPC or ARM multicore microprocessor with high-density DDR4 memory is also an ideal embedded computing platform, suitable for high-reliability and performance applications such as industrial control and aerospace.

 

Although NXP provides for design engineers a complete referenced design board, hardware and software development platform for their microprocessor solution; for high-reliability embedded computing application such as UAV, many experienced service providers are offering more adapted and customized System-on-Module (SOM)and corresponding services. For example, France Teledyne e2v’s Qormino product was integrated in a reference board and is compared in Figure 2 with the original reference system of the NXP microprocessor developed by Holland’s Sintecs. A large benefit in PCB real estate, due to the integration of the memory into the module is visible and shows that Qormino overcome the first obstacle to SWAP challenge:  the size.

 

Figure 2: Board size comparison of QorIQ T1040 microprocessor + 4GB memory reference design. (Source: Teledyne e2v)

 

Let's take the QorminoQT1040-4GBSystem Module developed by Teledyne e2v as an example to illustrate how SWaP problems in UAV design are solved one by one. Qormino is an embedded computing system module of small size, low power consumption and powerful processing capability, which integrates QorIQ series microprocessor and 4GB DDR memory in a 44X26mm interposer, especially suitable for the design and development of military and civil UAVs. The performance characteristics of QorminoT1040-4GBSystem Module is shown in the following table:

Feature

Specification

Processor

NXP QorlQ T1040 four-core@1400MHz

Memory

4GB DDR4 SDRAM, with 8-digit ECC Protection

Size

44x26mm

Power Consumption

<7W

Range of working temperature

Military-level: -55°C- 125°C

Safety

Avionics DO-254

Applications

Aviation, Radar, Industrial, Scientific Research, Network Communications

Figure 3: Features of Qormino T1040-4GB

 

As for hardware and software development environment, the Qormino products benefit from the large software and tools available from NXP and 3rd party. Teledyne e2v’s Qormino supports in particular the mature Linux SDK of NXP and the main stream RTOS support in the industry through specific bootloader and BSP, making the development of high-performance and highly reliable applications such as UAV much easier and faster.

Figure 4: Complete S/W development platform that is compatible with Qormino (Source: Teledyne e2v)

In addition to supporting the NXP QorlQ T1040 PowerPC processor kernel mentioned above, the Qormino series of Common Computer Platform Solutions also exists with the NXP LS1046 processors based on the ARM Cortex-72 kernel according to customer’s requirements. For UAV design requirements that require different processor and memory solution, Teledyne e2v is able to develop dedicated solutions. In summary, Qormino series of flexible solutions is a suitable product for customers developping high-end UAVs.

 

Qormino QT1040-4GB embedded computing solution offers the following benefits for UAV design:

 

1.       Computing Acceleration

Innovative data path accelerating architecture (DPAA) technology can effectively manage data flow, balance computing load to specify core.

AltiVec technology uses complex algorithms to speed up processing of dense vector data, thereby significantly improve parallel processing performance of radar and imaging signal.

DDR4 4GB memory integrated in the board can support up to 1600MT/s of data transfer rate and effectively solve the memory interface separation and timing deviation problems.

 

2.       Hardware Virtualization

◦ Supports multiple OSs at the same time;

◦ 3 levels of instructions: user, supervisor and Hypervisor, to coordinate running of

Multiple virtual machines (VM);

◦ Processor partitions are made to ensure system redundancy.

 

3.       Advanced Communication Interconnection Support

◦ Multiple built-in peripheral interfaces required for aviation and military systems, including ARINC 429;

◦ Eight 5 Gbps Serdes buses support high-speed bidirectional links;

◦ Four v2.0 PCI express controllers can work with external ASIC or FPGA.

 

4.       High Reliability and Service Life Management

Proprietary semiconductor lifecycle management (SLiM) service can provide for up to 15 years of components supply guarantee for UAV developers;

Centralized management and safe supply of proven components of original plants;

Effectively prevent counterfeit of components, reduce the risk of system failure.

 

Other SWaP challenges: sensor, RF/microwave device and power management

Sensor

To achieve timely and effective sensing and avoid collision, UAV needs many sensors to collect flight data and provide timely operational feedback, including airflow sensor, inertial measurement sensor, tilt sensor, magnetic sensor and engine air inlet sensor. The bulky sensor not only increases the weight of the UAV, but also causes many problems such as flight imbalance and instability and its power consumption also has a negative impact on power supply and endurance. All of these problems have driven sensor vendors to develop sensors that are lower in power consumption, small and lightweight to address the challenge posed by UAV design.

 

Antenna arrays and RF/microwave devices

The wireless communication function of UAV design is mainly to send and receive information between UAV and ground control station, as well as to conduct safe navigation through satellite positioning and M2M communication with other flying objects in the air. The use of antenna arrays at both ends of the wireless channel helps in beam directional control, as well as reducing signal transmission power consumption, increasing data transmission rate and expanding communication range.

 

The strict requirements of UAV design for high performance, high efficiency and small size also drive the technical development of RF and microwave devices from traditional separated packaging to mixing with digital technologies, such as the development of GaN solid-state power amplifier and even the integration of diode switches, GaAs LNAs, GaN-on-Si PAs and other components on a package. To meet UAV customers' demands for SWaP and cost, some RF/microwave device suppliers have also developed RF BGA packaging devices.

 

Power management

As for UAV power management, designers are concerned with size (S), weight (W), power density (P), power weight ratio, efficiency, heat management, flexibility and complexity. Small size, light weight and high-power density (SWaP) allow UAV to carry more payload, to have a longer flight and complete more tasks. High flexibility and low complexity make power system design easier.

Depending on load requirements of subsystems, the UAV has several power sources to choose from, among which lithium-ion battery is a common power source. Due to its small size and low cost, it is an ideal choice for the 100W of UAV which can run for several days. For special purpose UAVs, consideration may also be given to the requirements of power package, service life, temperature range and working environment, etc.

 

Conclusion

Led by Amazon and DJI, leading UAV manufacturers have triggered the rapid development of civilian UAV market. Strong market demand and fierce competition also put forward high requirements for UAV design, which can be simply summarized as SWaP. In this paper, an embedded Common Computer Platform Solution, Qormino, developed by Teledyne e2v is used as an example to discuss how to deal with the SWaP challenges. Other UAV functional modules’ technical innovation dedicated to cope with SWaP are also briefly introduced. I hope this article will be helpful to UAV design engineers and enthusiasts. If you have any ideas or suggestions, please feel free to share with us.