Altitude and Velocity Estimation of a Model Rocket

open_access
Open Access
Author:
Mohn, Lillie
Area of Honors:
Mechanical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
Matthew Brandon Rhudy, Thesis Supervisor
Bryan Wang, Thesis Honors Advisor
Cesar Martinez Garza, Faculty Reader
Keywords:
Engineering
Mechanical Engineering
Rocket
Model Rocket
Rocketry
Model Rocketry
High Power Rocketry
Altimeter
Altimetry
Sensor
Sensor Fusion
OpenRocket
Arduino
AdaFruit
JollyLogic
Estes
Low Power Rocketry
GPS
IMU
Barometer
Pressure Sensor
Unscented Kalman Filter
UKF
Kalman Filter
State Estimation
Abstract:
The goal of this project is to develop a low-cost rocket altitude sensor for students and beginner rocketeers. A sensor package consisting of a pressure sensor, a GPS, two inertial measurement units (IMUs), and a datalogger were tested on a high-power rocket. The sensors were coded using Arduino. Other measurements taken included altitude and speed using a JollyLogic AltimeterTwo and altitude using an Estes AltiTrak. Results from the custom sensor package were compared against the AltiTrak and OpenRocket simulation data. The AltimeterTwo did not produce a reading. Results were also run through an Unscented Kalman Filter (UKF) to estimate speed. From this flight, it was determined that the GPS was not a reliable altimeter, while the pressure sensor was more accurate and easier to use. Results from the two IMUs closely resembled one another. Speed estimation from the UKF somewhat matched the shape of the simulated speed curve, but more testing was required. Then, a smaller sensor package was made with just the datalogger, the pressure sensor, and the smaller of the IMUs. This streamlined sensor was tested in a series of low-power flights to resemble launch conditions of the target audience. Results were run through a UKF, and were compared against the OpenRocket simulations, the AltimeterTwo, and the AltiTrak. Altitude from the pressure sensor closely matched the simulated altitude, while the AltimeterTwo consistently read higher altitudes, and the AltiTrak consistently read lower altitudes. Speed estimation from the UKF was not reliable, and varied significantly between flights. Removing the IMU, which is not necessary for altimetry, the final sensor package costs $36.30. This is a significant price cut from the $79.95 cost of the JollyLogic. For simple altitude estimation, the sensor package developed in this work is a viable option for beginner rocketeers.