Microgravity Testing Platform: Controls Team

The NASA Microgravity Project consists of Mechanical Engineering Senior Design projects that aim to develop a new process for testing CubeSats in a microgravity environment below 10−3G. To accomplish this, five senior design teams are working on various aspects of a small drop package, released from a weather balloon, to test CubeSats by simulating microgravity conditions in freefall. The monocoque will fall from 100,000 feet during which the testing platform will experience about 20 seconds of quality microgravity. The goal of the Controls Team is to develop a proof of concept control system that corrects for any perturbations during the fall; this prolongs the period of acceptable microgravity. Implementing a reaction wheel system within the drop package achieves this goal. The system consists of a flywheel driven by a DC motor that applies a corrective torque to the monocoque. An inertial sensor determines the absolute orientation of the package using a 3-axis accelerometer, gyroscope, and magnetometer. An Arduino Uno running a Proportional Integral Derivative control loop outputs appropriate commands to the motor. This control system allows for responsive attitude control of the monocoque during freefall and maintains the microgravity environment throughout the CubeSat test.