The Flying Squirrels team is composed of PhD and MSc students
from ISAE SUPAERO/ONERA (France). It was selected by ESA (European Space
Agency) for the Fly Your Thesis! 2017 program to carry out an experiment
in a parabolic flight campaign. This experiment consists in testing an
innovative system to control the attitude (orientation in space) of small
satellites (nanosatellites). The attitude control system is composed of a
new configuration of control moment gyro actuators (see video
below) and of a new steering law to control nanosatellites, adapted
for future space missions.
The Fly Your Thesis! programme
The European Space Agency (ESA) Education Programme has the
objective to inspire and motivate young people to enhance their
literacy and competence in science, technology, engineering and
mathematics (STEM disciplines), and to pursue a career in these
fields, in the space domain in particular. To this end, it offers a
number of exciting activities that range from training and
classroom activities that use space as a teaching and learning
context for school teachers and pupils, to real space projects for
university students.
The Fly Your Thesis! (FYT) programme gives master and PhD
candidates the opportunity to fly their scientific experiment or
technological research in microgravity conditions. The experiments
can be related to fluid physics, chemistry, biology, material
sciences, heat transfer and astrophysics. The parabolic flight
campaign takes place on the Airbus A310 Zero-G, which is operated
by Novespace from Bordeaux, France. Each campaign consists of a
series of three flights of 30 parabolas each. These will provide
about 20s of microgravity each.
Flying Squirrels team, from left
to right: Antoine
Brunet, Hélène Evain, Thomas
Solatges and Adrien Dias Ribeiro.
Our team is composed of:
Daniel Alazard is our endorsing
professor from ISAE SUPAERO.
Hélène Evain is a French PhD
student, funded by ONERA (the French aerospace lab) in the
DCSD department and CNES (the French Space Agency) in
Toulouse (France), and academically affiliated with ISAE
SUPAERO. Her PhD topic is the study of new configurations
of Control Moment Gyro clusters and design of the steering
and attitude control laws. Therefore, this experiment is
integrated in her PhD. She is the team leader of this
project, defines the scientific objectives, and develops
the control laws and the maneuvers to be tested. After the
campaign, she will analyse the experimental data and
publish with the teams the results in journals and
conferences.
Thomas Solatges is a French PhD
student at SITIA company (Nantes, France) and affiliated
with ISAE SUPAERO and ONERA. He works on the design,
building and control of a large scale and highly dynamic
flexible robotic arm intended to launch and recover small
fixed wing planes (5kg to 10kg) from a moving ship. He
has designed and built many systems such as fixed wing and
multirotor drones. He handles the mechanical design,
system design of the nanosatellite and builds the
prototypes. He is the technical leader of the team.
Antoine Brunet is a French PhD
student, funded by ONERA (the French aerospace lab) in the
DESP department and CNES (the French Space Agency) in
Toulouse (France), and academically affiliated with ISAE
SUPAERO. His PhD topic is the study of new multiscale
numerical schemes to simulate the impact of solar
generators on the electrostatic charging of a satellite.
In this team, he is in charge of the software development,
both for the embedded computer and the monitoring system.
He is also in charge of the experiment operations.
Adrien Dias Ribeiro is a French
MSc student, studying at EI.CESI Toulouse and University
Paul Sabatier. He is studying electrical engineering,
embedded systems and robotics at the university. He is
also an apprentice at ONERA (The French Aerospace Lab) in
the DESP department, he is working on the automation of
test bench (vacuum chambers) for space applications. On
this project, he is doing the electronics of the system.
He will design electronics board for power conversion,
communication and electrical safety. He is also in charge
of project management.
Our experiment design
The main objective of the experiment is to test a new attitude
control system (system to control the orientation) for small
satellites (nanosatellites). This system includes a Control Moment
Gyro cluster composed of six actuators, and a new in-house steering
law that controls the actuators.
The nanosatellites have more and more needs for agility and
accurate pointing, and Control Moment Gyro clusters have proven to
be very power-efficient and have more torque capabilities than
other attitude actuators for the same mass and electrical power in
satellites. For micro-satellites, their use is not common because
of the complexity of steering a cluster, and few technologies are
available in the market. We therefore propose a new mechanical
design of a CMG cluster, fitting in a nanosatellite, with equipment
available in the market, and to test in microgravity the
performance of the new steering law by carrying out typical
maneuvers a nanosatellite may have to perform, with tests of
reliability in case of actuators failures.
The Control Moment Gyro cluster contains six identical CMGs.
Each CMG has two actuators: one flywheel motor will rotate the
flywheel at a high constant velocity, and one gimbal motor will be
controlled to provide the required gyroscopic moments.
The main controller of the nanosat is a Raspberry Pi 3 with a
PCB shield holding electronic components and connections to sensors
and other electronic systems such as one I2C IMU.
Planned maneuvers
During the flights, the cubesat will perform several different
maneuvers to assess the performance of the CMG cluster and of its
control law.
At the beginning of each parabola, one maneuver will be asked to
the nanosat, and it will have to perform it during the 20 seconds
of microgravity. The three types of maneuvers are:
Fixed pointing: the nanosat will have to stay fixed in a
given orientation despite the external perturbations during
the whole parabola. This simulates a mode where a satellite
in space has to keep its solar panels fixed towards the Sun
to charge its batteries, or when a satellite needs to keep
its antennas fixed towards the Earth to communicate with
the ground stations.
The goal is to remain pointed in a fixed direction, by
rejecting the outside perturbations.
Rapid large reorientations of the nanosatellite : the
nanosatellite will have to rapidly turn around itself to
point in a different orientation.
Follow a target: it models a space debris inspection
mission where a nanosatellite has to keep its camera fixed
relatively to a moving object. To do so, a camera will be
placed inside the nanosat that will track a target (for our
experiment, probably a ball of foam).
Each maneuver will also be tested with simulated failures of one
or two actuators switched-off during these parabolas.