How can I design a basic guidance system for my model rocket?

[veganode]

I'm building a model rocket from scratch; I'm now in the phase of designing a simple guidance system:

* Radio transmitter (From ground), Receiver on the rocket to get the basic orders Up, Down, Right, Left

* A gyroscope on the rocket to get the real position of the rocket and to update the steering orders depending on the rocket position

Can you provide me with some resources on how to do this?

 

[chroot]

Well, veganode, you're attacking an absolutely formidable problem, one that took decades of work by thousands of people to accomplish.

1) The thrust phase of a model rocket motor is only a couple of seconds long, and you'll only have active control during that time. You could conceivably add some movable control surfaces to the rocket, so you could control it during its descent, but control surfaces small enough to not interfere with the ascent won't really be able to have much effect.

2) The gimbals needed to adjust the thrust angle on a rocket motor are formidable. You will need quite good machining skills to make such devices.

3) You won't need just one gyroscope; you'll need three, one for each axis. You'll also need three linear accelerometers, plus the electronics to decode the sensor values and solve a complex set of differential equations to give you the position of the vehicle. You're looking at microprocessor-level electronics, probably a StrongARM or 286 or better. It took tens of thousands of man-hours of work to make an inertial guidance system that could fit in a cubic foot; you simply will not be able to accomplish it by yourself. Here's a document on the history of inertial guidance systems: http://www.imar-navigation.de/download/inertial_navigation_introduction.pdf

4) You can purchase a variety of off-the-shelf radio control equipment from a hobby shop. You can buy the transmitter and receiver units, plus servos and other equipment.

My honest advice? Scrap the idea of building an inertial guidance system. Scrap the idea of gimballing a rocket motor. Go to a hobby shop, buy a pre-made model airplane body and radio equipment, and start small. Once you're an expert on radio controlled airplanes, then you can start strapping rate gyros and microcontrollers in them to start learning guidance. It's a very, very long road ahead.

- Warren

 

[FredGarvin]

Holy crud...what kind of rocket are you building that you need a guidance system on? Like Chroot said...good luck. I have seen missile guidance systems and they are very complex.

 

[veganode]

Thanks, I really Appriciate your help

 

[russ_watters]

My honest advice? Scrap the idea of building an inertial guidance system. Scrap the idea of gimballing a rocket motor. Go to a hobby shop, buy a pre-made model airplane body and radio equipment, and start small. Once you're an expert on radio controlled airplanes, then you can start strapping rate gyros and microcontrollers in them to start learning guidance. It's a very, very long road ahead.

As an example, my senior year in college, one team took on autonomous guidance of an RC plane as their project. I don't know if they got it to work or not, but either way, its a complicated thing that was the subject of a year-long project for about-to-graduate mechanical and electrical engineers.