Learning the Basics:
Attitude Determination and Control
HERE!
With the CubeSat whipping around at 8km/s, the role of the attitude determination and control system is to ensure the correct orientation at all times.
To put it in perspective, if the Earth is right here, then we are controlling our satellite which is... (wait for it...)
What is Attitude
Determination and Control?
An attitude determination and control system (ADCS) controls a satellite's orientation in space.
With sensors and other mechanisms, the same side of the satellite can always face the Earth.
ANY QUESTIONS?
Magnetism At Work
Feel free to ask any of the volunteers!
The magnetorquers have magnetic fields that pull on the Earth's (much larger) magnetic field. This causes the CubeSat to align with the Earth, allowing the satellite to correctly point itself in space.
ADCS Components
Ex-Alta 1 has two components that control its position.
Magnetorquers: electromagnets that align the satellite with Earth's magnetic field.
Reaction wheel: a rotating flywheel that counters the movement of the satellite in two directions.
Rate Gyroscopes
Rate Gyroscopes measure the rate of rotation - the speed at which the satellite is orbiting
Magnetorquers
Current
These are electromagnets - wire with an electric current flowing through, resulting in a magnetic field.
S N
Since they provide useful torque (a force that spins the CubeSat around), they are also called torque coils.
Magnetorquer Experiment
Watch as we hang a model of Ex-Alta 1 in the centre of an electromagnet and turn it on... the satellite will align itself to the magnetic field just like in space!
Nadir Sensors
Nadir Sensors work like a camera. They sense when the earth is below Ex-Alta 1. This tells us if the CubeSat is spinning or oscillating.
Reaction Wheel
Since there is nothing to push off of in space, a reaction wheel can be used to prevent unwanted spinning.
Like the moon, the same side of the CubeSat will face the Earth at all times. This makes communication much easier!
Magnetometers
Magnetometers measure magnetic field strength on our satellite. Magnetometers also measure the Earth's magnetic field and the direction the field is traveling, allowing us to find the latitude of the satellite.
Wheel Goes Round and Round
An electric motor powers a flywheel, which causes the CubeSat to spin about its centre of mass,.
fixing the orientation of the satellite,except in the direction of the wheel's axis.
Sun Sensors
Reaction Wheel Experiment
When the spinning wheel is tilted, the boy on the rotating platform spins! Angular momentum must be conserved in the closed system.
Sun sensors use a photodiode (which produces voltage in the presence of light) to tell us where the satellite is with respect to the sun and how fast the satellite in rotating.
Sensors
Sensors for determining Location:
Sun Sensors
Magnetometers
Rate Gyroscopes
Nadir Sensors