Tech Briefs Magazine - May 2021 - 32

Aeronautics
Hinge Design Helps Quadrotors Climb
The new hinge is the key to get loadbearing, large quadrotors to climb a few dozen feet
in seconds.
Army Research Laboratory, Aberdeen Proving Ground, Maryland

esearchers invented a hinge that
improves how quickly a quadrotor
the size of a king-sized mattress can ascend from the ground to the rooftop of
a two-story building, particularly with
large payloads. The hinge is located at
the root of the quadrotor blade next to
the hub so that the blade pitch changes
with rotor speed.
As quadrotors and similar aircraft are
scaled up, the extra inertia of the rotor
blade slows them down. It can take a

long time for lightweight electric motors
to change the rotor speed and thrust,
which ultimately impacts the vehicle's
speed, range, and flight stability. With
the new coupling, the thrust becomes
more sensitive to changes in rotation per
minute (RPM).
The difference is that large quadrotors carrying these loads could climb
roughly 25 feet in as little as two seconds
with the hinge, instead of three or four
seconds without it.

The new hinge enables loadbearing, large quadrotors to climb a few dozen feet in seconds. (U.S.
Army graphic)

Increasing the thrust sensitivity to
changes in the RPM will allow for greater
control authority and more agility. Helicopters with four rotors, commonly referred to as quadrotors or quadcopters,
are part of a family of unmanned aircraft
systems that have two pairs of counterrotating rotors and propellers. These
vehicles can hover, fly forward, and perform vertical takeoffs and landings, similar to helicopters.
Common requirements for Army
quadcopters include speed, flexibility,
adaptability, providing real-time surveillance and carrying payloads. This invention will likely improve agility without
fully committing to a swashplate and the
weight penalties associated with it.
Designs usually are made around the
issues of responsiveness in one of two
ways. A swashplate is added to actively
control the blade pitch or smaller rotors
are put on the aircraft like an octacopter.
Both of these solutions weigh more,
which means the aircraft can't carry as
much gear, cameras, or batteries.
For more information, contact DEVCOM,
Army Research Laboratory Public Affairs at
703-693-6477.

System Helps Drones Detect and Avoid Power Lines
This technology provides drones sufficient time and distance to react, avoid wires, and
navigate follow-on maneuvers.
Army Research Laboratory, Adelphi, Maryland

esearchers developed a sensor and
software application to detect and
avoid energized power lines in the vicinity of unmanned aerial systems (UAS).
The goal is to provide drones sufficient
time and distance to react, avoid wires,
and navigate follow-on maneuvers.
The approach uses a unique configuration of field and 3D sensors in conjunction with low-power processing methods.
This resulted in detecting power lines
and informing the device's autopilot to

prevent collision with the wires. Power
lines generate large fields that can be
easily detected with low-power, low-cost,
passive electric- and magnetic-field sensors. This method allows UAS equipped
with the sensors to use smaller, lowerpower, and lower-cost sensors to detect
the location and Poynting vector (i.e. the
directional energy flux density) of nearby power lines. This allows the UAS to
autonomously avoid or navigate alongside the detected power lines.

www.techbriefs.com

Cov

ToC

While existing wire-detection and
wire-avoidance technologies that use
radar and/or optical sensors have had
commercial success, they are known to
be expensive, bulky, and power-intensive
with technical limitations. The detection
algorithm will result in size, weight,
power, and cost reduction. By combining both sensing modalities in one sensor, the researchers estimated the direction of power flow, something no traditional sensor can do.
Tech Briefs, May 2021

http://www.techbriefs.com http://www.abpi.net/ntbpdfclicks/l.php?202105TBNAV

Tech Briefs Magazine - May 2021

Table of Contents for the Digital Edition of Tech Briefs Magazine - May 2021