Date of Award

7-2026

Degree Name

MS in Aerospace Engineering

Department/Program

Aerospace Engineering

College

College of Engineering

Advisor

Eric Mehiel

Advisor Department

Aerospace Engineering

Advisor College

College of Engineering

Abstract

The Cal Poly Spacecraft Attitude Dynamics Simulator (SADS) is an ongoing project that seeks to enable the simulation and validation of sensors, actuators, and control logic related to spacecraft attitude control. The SADS platform rests atop a spher- ical air-bearing device which allows for nearly frictionless rotation in all three axes. The orientation of the platform is controlled by four reaction wheels arranged in a pyramidal configuration. Over the past few years, there have been significant updates to the reaction wheel subsystem, as well as requests for a more capable central com- puter. Therefore, a new system architecture for the SADS platform was proposed. The design was made to closely replicate the distributed command architecture of a satellite, with modular subsystems and primarily digital interfaces.

A new Linux-based Raspberry Pi 5 computer has been chosen as the new main control unit (MCU) due to its rapid software iteration compared to the previous STM32 microcontroller, native support for wireless control, and greater computational ability. The MCU is responsible for reading attitude data from the Inertial Measurement Unit (IMU), reading reaction wheel speeds, computing and commanding torques to the reaction wheels, and posting telemetry to the ground station for visualization and analysis. A custom Printed Circuit Board (PCB) was designed to control each of the four reaction wheel Brushless DC motors. Any PC or remote device can connect to the MCU via Raspberry Pi Connect, which enables the display of telemetry data in real-time.

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