Aerospace and Electronic Systems Magazine October 2017 - 43

Changey et al.
the gun, then GPS satellites are not
visible anymore). Spikes are again
measured at time t = 495.8 seconds,
due to the deployment of a parachute.
Then, the last spike on the barometer
data occurs when the GLMAV hits
the ground. One can notice than the
Kalman filter has a smoothing effect
on both the barometer spikes and on
the GPS altitude estimates. Data are
then grouped into shared memory to
be available to other tasks that need
it, mainly the main task that runs the
control laws.
The main task deals with running at a fixed frequency of 100 Hz
the control loop containing the algoFigure 6.
rithms for the stabilization and conSensor management and storage of data in memory.
trol of the drone. To do this, the task
has access to the sensor data and operator instructions. It also transmits
data for display on the ground station or for onboard recording. By the
use of the sensor data and operator
instructions, control algorithms calculate the speed and position instructions that are sent to the actuators.
The algorithms running in the control
loop were developed by the CRAN
and are summarized in [8].
The motherboard communicates
with the ground station computer
via the ZigBee protocol. It receives
the high-level commands from the
radio command or from the ground
station computer. These commands
and onboard data measurements
are transmitted to the ground station computer to be displayed or for
processing. Figure 9 shows a screenshot of the ground station computer.
The interface was developed by the
HEUDIASYC. The current selected
Figure 7.
tab depicts the evolution of the Euler
Digital filtering of the end speed of rotation of the gyroscope along the x-axis.
angles and the vehicle speeds providing the attitude of the GLMAV. More
information, such as motor speeds, vehicle position, tuning gains,
ELECTRONIC SYSTEM FOR MOTOR CONTROL
and the status of the drone, can be displayed. In the background,
the debug console also displays real-time data in raw form.
The GLMAV engines are brushless synchronous motors and conPresently, a commercial radio control is used for the commusist of permanent magnets on the rotor and coils on the stator.
nication between the ground station and the GLMAV. A specific
These coils are suitably fed by the control system to generate a
module was developed and added to the radio control that allows it
rotating field driving the rotor. Every moment, one of the three
to transmit with a 2.4-GHz ZigBee protocol. Aboard the GLMAV,
motor phases is not powered. This phase becomes the seat of a
a specific task is executed that acquires the status of radio control
counter-electromotive-induced voltage used by the electronic sysswitches and levers and transmits the corresponding instructions
tem to derive the rotor position and thereby adjust the control sigto the main task.
nals. This ensures the engine autopilot.
OCTOBER 2017

IEEE A&E SYSTEMS MAGAZINE

Table of Contents for the Digital Edition of Aerospace and Electronic Systems Magazine October 2017