Team Rocket
Design and Development of a CubeSat Attitude Control Test Assembly
From left: Brialyn, Yosef, Jonah, Mars
Mission Statement
Design and build a testing assembly, enabling the Hawaii Space Flight Lab to test and validate the Attitude Determination and Control Subsystem of their upcoming NEUTRON-1 3U CubeSat mission.
Project Summary
CubeSats are a category of nanosatellites; nine orders of magnitude smaller than a standard satellite. This small size makes them cheaper, and faster to produce, allowing for a design that enables testing of more recent technological advancements as opposed to a standard satellite. CubeSats feature an Attitude Determination and Control System (ADCS) that is used to correct rotation of the CubeSat body upon deployment, and allows for subsequent orientation control. The ADCS is controlled by an onboard computer and is able to provide attitude control using actuators that will move or rotate the CubeSat body. The functionality of the satellite ADCS is vital to the success of the satellite mission and is therefore required to be properly tested and verified prior to launch.
The motivation for this project was to assist the Hawai’i Space Flight Laboratory (HSFL) in updating their satellite testing facility to be able to accommodate the smaller size of a CubeSat. This requires simulation of spacecraft dynamics on Earth to enable HSFL to test and validate the ADCS actuators of their upcoming NEUTRON-1 3U CubeSat mission. The resulting approach was to design and construct an assembly for testing and validation of the ADCS actuators of a 3U CubeSat whilst matching the moments of inertia to accurately simulate the rotational dynamics experienced in space.
ME 482 Gantt Chart
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ME 481 Gantt Chart
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Our final estimated budget is as follows:
Team Contribution: Most parts have been acquired online from ServoCity, Sparkfun, and McMaster-Carr.
HSFL Contribution: HSFL ordered the air bearing and built a pedestal in house.
The team’s concrete deliverables are as follows:
- A design trade study to select the rotational platform.
- CubeSat support table which will interface with the selected rotational platform, also supporting a mechanism that achieves a neutral balance of less than 1 deg/min of movement.
- 3D printed housing structure of a 3U CubeSat to accommodate the required components.
5APR2017:
The balancing mechanism design has been completed and assembled, which includes a system of manual coarse mass trimming mechanisms and motorized fine mass trimming mechanisms. The balancing mechanism co-locates the center of mass with the kinematically defined center of rotation of the air bearing hemisphere to within 1 micron.
A prototype of the CubeSat support table has been 3D printed, and the assembly is currently being tested in the HSFL clean room prior to making final design modifications and 3D printing the final prototype.
11Jan2017:
The design trade study has been completed and the rotational platform, a 100 mm spherical air bearing, has been chosen and purchased by HSFL per the team’s recommendation. The air bearing arrived during the winter holiday break.
The CubeSat housing has been 3D printed and is being prepared for testing.
- To meet the requirements for the testing assembly, a housing design with the same geometry as that of a standard 3U CubeSat dimensions was chosen.
- A modified 3U CubeSat structure was the chosen design since it can perfectly house all the components in their proper locations with respect to one another.
Our main focus at this time is the mass trimming system and support table.
The mass trimming system is important to obtain a neutral balance of the test platform on top of the air bearing. In order to create a proper mass trim system, the Team will:
- Procure stepper motors of minimal size and mass to drive the balance masses.
- Ascertain the correct size of the balance masses needed by the system.
- Craft a system for each of the primary XYZ axes.
- Connect all 3 systems via motor controllers to a Teensy Arduino.
- Program the Teensy Arduino to accept inputs from a remote control station to move the balance masses as desired.
Our main focus for this semester was the trade study for determining proper air bearing size.
SolidWorks was utilized to create the models of a CubeSat and the various sizes of hemispheres for spherical air bearings to obtain mass and moment of inertia (MOI) values. These values were then fed into a MATLAB Simulink program and used to choose the best size spherical air bearing.
27Nov2016:
09Nov2016:
06Oct2016:
Team has been brainstorming different designs in addition to the two provided designs by HSFL. Determining how the Trade Study will be conducted is at the top of our minds; that is, we need to first determine exactly *what* we need to know before we determine the *how*.
We 3D printed a 1U CubeSat in order to have a hands on idea of the scale of what we’re working with.
25Sep2016:
HSFL has given us two possible solutions regarding coincidence of Center of Mass and Center of Rotation, with as close a match for Moment of Inertia as is possible. The first design is to take a standard air bearing hemisphere and trim the top rim down, as the kinematic center of the sphere will not change, but will allow the CubeSat to be mounted lower, achieving coincidence. Bonus is being able to support 1U and 2U CubeSats in addition to a 3U. The second involves a much smaller hemisphere for the air bearing, mounted inside the test CubeSat itself, instantly achieving coincidence and having minimal inertial differences.
The Team
- Brialyn Onodera – Project Lead
- Yosef Ben Gershom – Systems Integrator
- Mars, Laird Rayno – Financial Advisor
- Jonah Ang
Hawaii Space Flight Lab Mentor
Senior Design Advisor
Contact Information
You can reach us via email at HSFLWorkerBees@gmail.com!
