Expectation
The project met most of our expectations. Although the launch demo did not meet our expectation, we were able to successfully demonstrate that the accelerometers and rate gyro sensor can accurately determine our location, as shown with in-lab tests and demos. The ejection charge fire, which verified that the sensor system was able to determine apogee. The secondary ejection charge fired at 9 sec, which was completely isolated from our system. We were able to hear and see two different ejection charges firing during the launch. The stepper motor also turned when we moved around in the lab. We were never able to verify the steerability of the parachute because it didn’t successfully deploy during the launch and drop in Duffield is not high enough to verify if the motor actually turn the parachute. However, when we tie on end of the parachute an inch shorter than the other, we did see the spinning and rotation about that point during the Duffield drop test.
Possible Improvements
If we could improve this project we would first use a more powerful micro controller. This problem is computationally intensive and we need to be able to do more calculations faster. Fixed point would not help on our processor since it can only shift one bit at a time which makes multiplication is not much faster than floating point. We would also use only digital accelerometers (with at least 12 bits of accuracy) through SPI and double precision for more accuracy. Finally we would implement the 3 gyro system for more accurate determination of orientation relative to our stationary axis.
Ethics
As electrical and computer engineers we follow the IEEE code of ethics as listed on http://www.ieee.org/web/membership/ethics/code_ethics.html . We understand that building a rocket poses a danger to the safety public in the event of a failure. We choose to launch on private property, while following all FAA regulations. We believe that this would keep the public safe since everyone on the private property knew about the launch. Furthermore there were no perceived conflicts of interest. While working in the lab, we only brought the avionics section. The ejection charge test was completed with a fuse or ammeter. No igniter or black powder was ever lit indoors. The residue from the launch left on the rocket would not pose any danger.
This project also required a lot of common sense. For example, when we were doing drop test. We had a long rope tied so that the item drop will never actually touch the ground (for the case of complete parachute failure). We also always had someone on the ground to clear the way before. We usually have one person dropping, one person filming/operating camera, and at least one spotter on the ground.
Before launch we discussed the reality of important safety measures going off properly during flight. We included a triple redundant parachute deployment system using the best data we had available to time them correctly. We used a simulation of the launch along with the engine datasheets in order to determine what we believed were safe numbers to prevent the rocket from becoming a projectile. No attempt of bribery occurred so this was not an issue.
In the launch conclusion section we acknowledge errors associated with the launch. Once again we would like thank Professor Land and all the TAs for help helping us overcome problems and errors. Also we would like to thank Analog Devices, Freescale, Linear Technologies, and ST Microelectronics for giving us samples which made this project possible. We attempted to improve technology by attempting to design a cheap inertial navigation system for rockets. We hope that people will use what we have done and expand upon this so that it may one day be applied to applications that benefit society. Potential applications include delivering supplies and landing in hard to get to places. As rocketry is a dangerous activity, one member of the team is certified Level I rocketry NAR member.
Intellectual Property Consideration
We used some of Professor Land’s code and modified it for the ADC. We used the same circuit as those found in a previous ECE 4760 project – Wall of Pong (Spring 2007) for the stepper motor and stepper motor diagram.
Interference
We did not use RF or create noises or disturbances that could interfere with other peoples projects around us.
Credits
Vendors
We
would like to thank all the vendors that provided us with parts,
samples, and technical support to make this project possible.
·
Analog Devices
·
Freescale
· Linear Technology
Technical References/Reports
1.
Federal Aviation Regulations Part 101,
Section A, Model Rockets,
www.access.gpo.gov
2.
National Association of Rocketry (NAR) Model Rocket Safety Code,
www.nar.org/NARmrsc.html
3.
27 CFR
55.1, BATF (Bureau of Alcohol, Tobacco, and Firearms) regulations,
www.access.gpo.gov/nara/cfr/waisidex_02/27cfr55_02.html
4.
D.
Levin and Z. Shpund, Canopy Geometry Effect on the Aerodynamic Behavior
of Parachutes, Journal of Aircraft, Vol 23, No. 5, September 2007
5.
Hogue,
Jeffry. Applying parachute canopy control and guidance methodology to
Advanced Precision Airborne Delivery Systems. AIAA Aerodynamic
Decelerator Systems Technology Conference, 13th,
6.
A.
Taylor, Mars guided parachute system. The Boeing Company. AIA-2006-7430.
7.
Glen
Brown, The Affordable Guided Airdrop System (AGAS), The Boeing Company,
Professors and TAs
We would like to thank all the professors and TAs for assisting us with this project. Professor Bruce Land assisted us with all phases of the project – design, test, and debugging. Professor Mark Campbell assisted us with more of the high level conceptual design stuff. He teaches the feedback control system course at Cornell. The TAs were always around in the lab to help us debug the project and provide ideas when we faced problems.