Jose Maria Estevez's Discussions
Gyroscopes vs Acceleometers
Started this discussion. Last reply by Caleb Chamberlain Aug 14, 2009. 28 Replies 0 Likes
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Caleb Chamberlain replied to Jose Maria Estevez's discussion 'Gyroscopes vs Acceleometers'
Roy,
Yeah, we've had our eyes on these guys; they just won the International Aerial Robotics Competition (IARC) with the setup they describe in this paper.
We are a little behind them... we made the mistake of designing our own quadrotor, so…
Roy Brewer replied to Jose Maria Estevez's discussion 'Gyrospes vs Acceleometers'
Caleb,
Did you see this paper?
Autonomous Navigation and Exploration of a Quadrotor Helicopter in GPS-denied Indoor Environments, Markus Achtelik, Abraham Bachrach, Ruijie He, Samuel Prentice and Nicholas Roy
(found it using Google Scholar)
- Roy
Caleb Chamberlain replied to Jose Maria Estevez's discussion 'Gyrospes vs Acceleometers'
No; as long as there is enough upward force to keep the aircraft's altitude fairly constant, the acceleration of the body is independent of its mass (because heavier bodies require higher thrust to maintain altitude, which induces larger…
Roy Brewer replied to Jose Maria Estevez's discussion 'Gyrospes vs Acceleometers'
bGatti, Xander,
I don't think the physics supports what you're thinking. The thrust vector is always aligned with the body Z axis regardless of the mass properties or rotation rate.
One thought I had along those lines is that if the arms…
Xander replied to Jose Maria Estevez's discussion 'Gyrospes vs Acceleometers'
Yeah, inertia occurred to me too, but hadnt worked out the physics to back that up. Not sure momentum is really separate from the force equations we're already using.
bGatti replied to Jose Maria Estevez's discussion 'Gyrospes vs Acceleometers'
I'm beginning to think that the inertial framework of these devices has a lot to do with the response of the accels on angular movement; specifically, in the time it takes for the inertial moment to react to a change in thrust vector, the…
bGatti replied to Jose Maria Estevez's discussion 'Gyrospes vs Acceleometers'
A bit rich on jargon, but interesting:
I think what you're saying is that, like gravity, the sum of polar magnetism is largely constant, and with a multi-axis magnetometer, you should be able to detect the attitudinal (non-compass-axis) angle…
Caleb Chamberlain replied to Jose Maria Estevez's discussion 'Gyrospes vs Acceleometers'
It looks like we have a lot of material on how accels behave here where I am studying (Brigham Young University), but we haven't published any of it... so I guess I was wrong when I assumed papers had been published on it. I made the assumption…
Caleb Chamberlain replied to Jose Maria Estevez's discussion 'Gyrospes vs Acceleometers'
Your research, BTW, sounds really interesting. Have you published anything on it yet? I would be interested to read it.
Caleb Chamberlain replied to Jose Maria Estevez's discussion 'Gyrospes vs Acceleometers'
Roy,
Earlier, I was too quick to say "accels are basically worthless." They are "worthless" in the sense that they can't really be used in the way everyone seems to use them. But they CAN (as you mentioned) measure the…
Caleb Chamberlain replied to Jose Maria Estevez's discussion 'Gyrospes vs Acceleometers'
Yes, of course you can combine a variety of sensors using any number of algorithm, perhaps most commonly a KF. What I am saying is that near hover the only thing that the accels can't give us much information that can be used to correct gyro…
Roy Brewer replied to Jose Maria Estevez's discussion 'Gyrospes vs Acceleometers'
Caleb
Can you please post those papers that go into detail about this? Don't get me wrong - I believe you completely! But, all the academic papers I've seen on quads or other hovering vehicles seem to imply the accelerometers give a…
Gilberto Pin replied to Jose Maria Estevez's discussion 'Gyrospes vs Acceleometers'
Well. I partially disagree. The problem is that if you use only the accelerometers to estimate the attitude of the quad, then you have not enough information to estimate also linear accelerations, and, if the body accelerates, then the estimated…
Caleb Chamberlain replied to Jose Maria Estevez's discussion 'Gyrospes vs Acceleometers'
That could be. Maybe I'll do some testing and see what happens.
Xander replied to Jose Maria Estevez's discussion 'Gyrospes vs Acceleometers'
The only way I could see the accels actually functioning is if we're reaching steady state a lot sooner than you think. Experimentally, giving a quad a 5 degree tilt seems to have it going at a pretty steady speed after the initial…
Caleb Chamberlain replied to Jose Maria Estevez's discussion 'Gyrospes vs Acceleometers'
In most cases, I think that the upward for will not always be m*g; even if you have an altitude hold loop running, it may not respond quickly enough to update the force vector in the event of a disturbance. The effect would be that the accels…
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