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Author Topic: Using CMGs for model rocket guidance  (Read 31 times)

Cosmoneer

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Using CMGs for model rocket guidance
« on: 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

Quote
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


« Last Edit: November 08, 2017, 01:34:28 PM by Cosmoneer »