Thermal Flow Sensors for Man-Potable Vehicles Applications
Man-portable air vehicles (UAVs) or micro air vehicles (MAVs)
can be used in
many dangerous civil and military missions without any risk
to human life, and they also have many potential industrial applications such
as plant supervision, power line and construction site inspection, pollution
and weather monitoring, forest fire and disaster control, etc.
All these vehicles operate
exclusively within the atmospheric boundary layer,
which typically extends up to 5 km above ground level
depending on surface heating, climatic conditions, and terrain. The flow in the
atmospheric boundary layer is dominated by horizontal transport of atmospheric
properties. As air travels over buildings and various obstacles, there will be
a local increase in wind speed. It has been shown that mean wind speeds above a
certain threshold can make the air speed vary substantially. When a steady 4.6 m/s magnitude wind is
presented it is inability of an MAV to reach its pre-programmed waypoints. This
degradation in performance puts the aircraft at risk and often leaves the MAV
unable to complete its mission.
In order to improve the performance
of the air vehicles a powerful onboard
sensing system is required. This sensing system can detect
individual air speeds in a turbulent boundary layer. Once detected, the
turbulent influence can be suppressed or eliminated by an action of micro
electromechanical devices.
As shown in figure 1, POSIFA
thermal flow sensors are ideal for the onboard
sensing system. These thermal flow sensors have the benefits
of miniature size, low power dissipation and fast response time, which is
essential for detecting turbulent flow. The miniature size allows for their installation
in small spaces without significantly interfering with the flow and consequently
altering its behaviour.
These thermal flow sensors can be
used for detecting the surface velocity
distribution over critical locations of the wing area, such
as the points of flow transition, reversal, or separation.
POSIFA thermal flow sensors can be
used to determine three flight parameters: air
speed, angle of attack and angle of sideslip. As shown in
figure 2, so as to do so an array of thermal flow sensors is installed over
critical locations of the wing area, such as the points of flow transition,
reversal, or separation. The signal of each thermal flow sensor is send to a
microcontroller through wireless communication. The microcontroller will act
the micro electromechanical device for suppressing or eliminating the turbulent
influence.
These thermal flow sensors can be
used for detecting the surface velocity
distribution over critical locations of the wing area, such
as the points of flow transition, reversal, or separation.
POSIFA thermal flow sensors can be
used to determine three flight parameters: air
speed, angle of attack and angle of sideslip. As shown in
figure 2, in order to do so an array of thermal flow sensors is installed over
critical locations of the wing area, such as the points of flow transition,
reversal, or separation. The signal of each thermal flow sensor is send to a
microcontroller through wireless communication. The microcontroller will act
the micro electromechanical device for suppressing or eliminating the turbulent
influence.
Figure 2. An Unmanned air vehicle equipped with a POSIFA
thermal flow sensor array controlled by a microcontroller.
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