Cosmos Forum
High Powered Rocketry Guidance Systems => Inertial Guidance => : Cosmoneer November 08, 2017, 01:18:11 PM
-
A question regarding usage of Cosmoneer CMGs (or larger versions) for model rocket guidance was submitted. This led to further emails and some questions on my part as to the legality and safety regarding guided rockets. Given the high-powered nature of the top end of the hobby, I expect safety to be paramount.
My fears aside, I continued to look around the internet for others who had attempted guided rockets. Most solutions are fin-based, followed by gimbaled motors or reaction control thrusters. At the bottom end you may have reaction wheels to control spin, but I have not yet found where a CMG design was used to control a rocket's attitude.
This forum section was create to give those who are curious or want to participate in the design of a hobby sized vertical stabilization system a place to share their ideas and struggles.
Below is a list of links to other projects for guided hobby rockets. If you have a link that is not listed, please let me know!
http://www.ibiblio.org/pub/archives/rec.models.rockets/ARTICLES/guidanceFAQ.txt
2nd Gyro torquing
Finally, there is a technique for controlling rocket attitude without fins,
gimballed motors or any outher external affectations. In fact, it's very
close to the presumed ideal of a gyro that "resists" external forces all by
itself. The technique was originally used to stabilize ocean liners along
their roll axis but is now used in some spacecraft to do attitude control
without the use of gas jets.
The first thing you need is a reference platform to tell you which way is
"up". This can be a small mechanical gyro with encoders on the gimbal axes
like we've been discussing, or even a non-gyro system like horizon sensors
(this is the way satellites do it) or a "target" sensor like sun guidance.
The second part is the control gyro. It must be fairly massive and positioned
somewhere around the rocket's CG. Actuators are placed on the gimbal axes so
that when the reference platform detects an error, say on the yaw axis, the
actuator twists the gyro's pitch axis which forces it to precess in yaw. If
you've got the signs hooked up right, this will counter the disturbing yaw
and put you back on track.
While the theory is good and has been proven out on real spacecraft (such as
the "Magellan" Venus orbiter) it all seems quite involved for a hobby rocket.
I'm sure someone out there will try it for just that reason :^)
http://psas.pdx.edu/
http://linuxdevices.linuxgizmos.com/ldfiles/article039/psas.html
https://www.scribd.com/document/118511360/lv2-avionics-design-pdf
http://www.ukrocketman.com/rocketry/gimbal.shtml
Forum threads where the topic was discussed:
https://forum.ausrocketry.com/viewtopic.php?t=1185
http://www.rocketryforum.com/showthread.php?132881-Blackbird-Project-Arduino-controlled-high-power-carbon-fiber-rocket