How does the UAV design of Amazon Prime Air respond to the SWaP challenge?

Article By : Steve Gu

 

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 3^rd 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.