The following text is a compilation of almost all of the major design teams behind the SUTS satellite and where they have gotten up to until now, what they are currently, and will be working on in the near future.
General
The Strategic Upgrades Testing Satellite (SUTS) is rapidly approaching the final stages of engineering model development and assembly. With the mechanical body arriving at the start of March, the team is looking forward to the assembly process. The engineering model of SUTS will include most electronic components. An image of the internals of the engineering model is shown below:
After the assembly is complete, the team will focus on compiling documentation about the assembly process, the satellite’s individual components, subsystems, and the testing plan. SUTS will undergo unit testing, meaning that the team will test the satellite’s full functionality to confirm that everything works correctly. After that, the satellite will move on to environmental testing.
Electronics Team
Developing an engineering model for SUTS requires that all of the engineering model grade subsystems and payloads are also finalized. By the month of February most of the subsystems have been designed, but still need to be soldered and tested to verify that the main board works as intended. Furthermore, in order for the subsystems to be able to communicate with one another, we need connections between them. The first thought might be to use traditional wires, but due to the limited space onboard SUTS, and to make the assembly easier, we will use PCBs that have connectors on them. Another prominent example is the deployer plate (not pictured above to show internal components) that connects the satellites sensors, actuators and one of our payloads to the rest of the system. Fortunately these boards are simpler than the subsystem so designing them shouldn’t take much longer.
Mechanics Team
The mechanics team will conduct a series of physical tests to check for shock, performance, vibration resistance, etc, later this year. The team received guidance on metal production drawings from Limitless Machining (Special thank you to Alan from LM!) and placed its first order for metal parts, which will be received in March. At the same time we are preparing structural components for vibration and shock testing.
Additionally, we are also preparing SolidWorks simulations, meaning – the computer renders final results using the variables provided. Those results will be used to prepare for testing, and after, changes in the overall design may also occur.
Software Team
The Software team has been working on completing the engineering model as well. This involved defining the system architecture of SUTS and actually implementing it. And of course re-implementing when we saw issues with the initial design. During the month of February most of our time was spent finalizing the services, meaning fixing bugs, testing their functionality and updating the firmware layout. At the same time, we are also building tools to let us test outside communications with the satellite, such as using a radio link. Due to the lack of time and the still ongoing tests of the COM module, the radio communications will probably not be used for the engineering model and instead will be simulated by a serial connection to the computer.
ADCS Team
Over the past year, the ADCS team has been working on simulating satellite flight in orbit. We finalized the attitude control controllers B-dot, PID, and LQR (Proportional-Integral-Derivative & Linear Quadratic Regulator), simulated the actuators (reaction wheels and magnetorquers), and modeled the sensors (Sun sensors and magnetometers). The simulations progressed from early implementation tests to a full orbit simulation, including detumbling, nadir pointing (which is when the satellite points the onboard instruments perpendicular to the surface of the earth.), and ground station tracking, which is needed for the overall maneuvering of the satellite when it is in orbit. Over the past month, we focused on implementing the attitude determination part of the simulation. This involved building observers that use simulated sensor readings together with the satellite dynamics to better estimate the satellite’s orientation and position. At this point, we have a complete attitude control and determination simulation that begins with detumbling, then initializes the attitude using sensor data, and continues with successful nadir pointing and ground station tracking.
While simulations got us closer to the real in flight algorithms, the SUTS engineering model deadline was also approaching. The ADCS team then made the final decisions of which actuators and sensors to use. We were able to test and eliminate previously chosen magnetometers and with the help from the electronics team we got an overview of the magnetorquers capabilities. Once the sun sensors arrive, we will proceed with testing and characterizing them and once the ADCS mainboard is ready, we will be able to do a few rotations with the reaction wheels.
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