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Author Topic: Arduino Quadcopter  (Read 18508 times)
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sbright33, the ENC-03R has a maximum angular velocity of about 300 degrees per second, at 50Hz.  So you can query the sensor 50 times a second to get an angle.  That's plenty of time to correct the vehicle's attitude without human input.
« Last Edit: February 12, 2012, 07:54:32 pm by KirAsh4 » Logged

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You're correct it can measure fast rotation.  That's about 6 deg in a Hertz!  ;-)  Sorry 6 degrees in 1/50 sec.  So we can stop it from rotating violently.  Let's talk about Yaw for now.  If it is spinning slowly, say 30 deg / minute, the ENC-033r will not be able to measure it.  It will return a zero value.  If we can't measure it, how can we stop it from happening?  MarkT said this sensor is for short term control only.  So we need another sensor.  But some copters don't have another sensor.  Am I correct?
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I don't know about other copters and their sensors or lack thereof.  So I can't answer that question.  Ask the makers of said quad, look over their code, see how they are doing it.
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My "theory" is that a Quad requires either an accellerometer or human input to keep from flipping.  Any other possibilities?
The IR sensor only works in some environments.
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My "theory" is that a Quad requires either an accellerometer or human input to keep from flipping.  Any other possibilities?
The IR sensor only works in some environments.
I'm pretty sure that at some point an accelerometer (or accel/gyro combo) is needed to tell the copter to balance itself. I haven't seen any IR ones before (only ones iv seen were built by a couple friends of mine in college). Guess if you really wanted to get pointless though you could make them balance off the signals of a few rangefinders (pointed at teh ground on different spots of your copter). But now thats just me being idiotic.

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You're correct it can measure fast rotation.  That's about 6 deg in a Hertz!  ;-)  Sorry 6 degrees in 1/50 sec.  So we can stop it from rotating violently.  Let's talk about Yaw for now.  If it is spinning slowly, say 30 deg / minute, the ENC-033r will not be able to measure it.  It will return a zero value.  If we can't measure it, how can we stop it from happening?  MarkT said this sensor is for short term control only.  So we need another sensor.  But some copters don't have another sensor.  Am I correct?

You might end up needing a second more accurate sensor to operate when the copter isn't moving around to keep it in line.
Yes this is total suck because it means you need another one (or few) of your ports on your arduino(or other controller) to accomplish the same task, or you could build a circuit to amplify the output of the gyro at its lower sensing range (basic instrumentation and controls), and have a digital port control when the "high speed low accuracy", and "low speed high accuracy" circuits are turned on. (when HSLA starts to get low switches over until an input is given or if the LSHA signal starts to get too high)
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If there's a human they can act as the drift-correction signal - either way (automated or manual) you need to combine the two signals (fast but with drift, slow but without drift) correctly.  Normally the gyro signal is a rotation matrix (DCM) or quarternion and the accelerometer signal is just a vector, so they aren't directly comparable.  If you don't grok 3D vector geometry it will be hard to code up the necessary algorithm.
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If you don't grok 3D vector geometry it will be hard to code up the necessary algorithm.

I thought coding was the process of implementation of an algorithm(s) ?

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So does everyone agree 3 cheap gyros alone will not keep a craft up for long without human input?
For the reasons mentioned above...
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This site has loads of information.

http://aeroquad.com/

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Thanks!  Reading...
Realized a cheap GPS will keep it from slowly drifting in 2 axes (tilting), compass in the 3rd, pressure in the 4th.
Not position that WILL drift over a 100' circle, but angle, even a slight tilt angle will make a measurable movement in GPS data.


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