Engineering Commons^™

On-Board Orbit Determination And 3-Axis Attitude Determination For Picosatellite Applications, John Arthur Bowen

Master's Theses

This thesis outlines an orbit determination and 3-axis attitude determination system for use on orbit as applicable to 1U CubeSats and other picosatellites. The constraints imposed by the CubeSat form factor led to the need for a simple configuration and relaxed accuracy requirements. To design a system within the tight mass, volume, and power constraints inherent to CubeSats, a balance between hardware complexity, software complexity and accuracy is sought. The proposed solution consists of a simple orbit propagator, magnetometers with a magnetic field look-up table, Sun sensors with an analytic Sun direction model, and the TRIAD method to combine vector …

Attitude Determination Of A Student Satellite Using On-Orbit Magnetometer And Temperature Data, Jacob Daniel Dimiceli

Master's Theses

An extended Kalman filter is modified to support only magnetometer data as a measurement for spacecraft attitude information. Actual on-orbit data from a student satellite is used in the filter from three different time periods and varying data frequencies. The extended Kalman filter has a thermal model that utilizes external temperature data as a verification tool for filter convergence and for parameter tuning. It can capture the frequency of temperature changes and the correct side panel being lit by the sun as long as the filter converges properly, but not the magnitude of the temperature at a specific time. A …

Validation Of Linearized Flight Models Using Automated System-Identification, Keith Eric Rothman

Master's Theses

Optimization based flight control design tools depend on automatic linearization tools, such as Simulink®’s LINMOD, to extract linear models. In order to ensure the usefulness and correctness of the generated linear model, this linearization must be accurate. So a method of independently verifying the linearized model is needed. This thesis covers the automation of a system identification tool, CIFER®, for use as a verification tool integrated with CONDUIT®, an optimization based design tool. Several test cases are built up to demonstrate the accuracy of the verification tool with respect to analytical results and matches with LINMOD. Several common nonlinearities are …

Comparison And Design Of Simplified General Perturbation Models (Sgp4) And Code For Nasa Johnson Space Center, Orbital Debris Program Office, Nicholas Z. Miura

Master's Theses

This graduate project compares legacy simplified general perturbation model (SGP4) code developed by NASA Johnson Space Center, Orbital Debris Program Office, to a recent public release of SGP4 code by David Vallado. The legacy code is a subroutine in a larger program named PREDICT, which is used to predict the location of orbital debris in GEO. Direct comparison of the codes showed that the new code yields better results for GEO objects, which are more accurate by orders of magnitude (error in meters rather than kilometers). The public release of SGP4 also provides effective results for LEO and MEO objects …

A Flight Simulation Study Of The Simultaneous Non-Interfering Aircraft Approach, Brian H. Reel

Master's Theses

Using a new implementation of a NASA flight simulation of the Quiet Short-Haul Research Aircraft, autopilots were designed to be capable of flying both straight in (ILS) approaches, and circling (SNI) approaches. A standard glideslope coupler was sufficient for most conditions, but a standard Proportional-Integral-Derivative (PID) based localizer tracker was not sufficient for maintaining a lateral track on the SNI course. To track the SNI course, a feed-forward system, using GPS steering provided much better results.

NASA and the FAA embrace the concept of a Simultaneous, Non-Interfering (SNI) approach as a way to increase airport throughput while reducing the noise …

Design And Control Considerations For A Skid-To-Turn Unmanned Aerial Vehicle, Tanner Austin Sims

Master's Theses

The use of Unmanned Aerial Vehicles (UAVs) are rapidly expanding and taking on new roles in the military. In the area of training and targeting vehicles, control systems are expanding the functionality of UAVs beyond their initially designed purpose. Aeromech Engineering’s NXT UAV is a high speed target drone that is intended to simulate a small aircraft threat. However, in the interest of increasing functionality, enabling NXT to accomplish wings level skidding turns provides the basis for a UAV that can simulate a threat from a missile. Research was conducted to investigate the aerodynamic and performance characteristics of a winged …