Espritmodel.com Telemetry Radio
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Old Nov 23, 2012, 07:37 AM
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Another thing I noticed about the pan response is that it seems very heavily damped, it seems to take several seconds to respond then several more to drift back to the neutral position.

A.
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Old Nov 23, 2012, 07:53 AM
Oxford Panic
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If I move a magnet past the fixed sensor the magnetometer seems to move the servo signal without drifting back but is still heavily damped. This leads me to believe the problem is with the accelerometer or the gyro, I'm suspecting the gyro right now.

Have I missed any important posts in this thread which gives some resolution to all this.

A.
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Old Nov 23, 2012, 09:36 AM
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Quote:
Originally Posted by AndyOne View Post
If I move a magnet past the fixed sensor the magnetometer seems to move the servo signal without drifting back but is still heavily damped. This leads me to believe the problem is with the accelerometer or the gyro, I'm suspecting the gyro right now.

Have I missed any important posts in this thread which gives some resolution to all this.

A.
If you set too high throw than your radio will center it not HT.

Try decrease it.

Also i think you should do the acelero calibration also.

I don't have other idea at the moment.
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Old Nov 23, 2012, 09:47 AM
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I decreased the gain on pan tilt and roll to 100 each but it's still the same. What do the other adjustments do...

End-> and End<-

And how do the centering controls do anything different to resetting the Arduino on the reset button.

There's a lot I don't understand about this project, this is becoming more and more obvious, may be I should read through the entire thread again to see if there's anything different I can do.
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Old Nov 23, 2012, 10:51 AM
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Quote:
Originally Posted by AndyOne View Post
I decreased the gain on pan tilt and roll to 100 each but it's still the same. What do the other adjustments do...

End-> and End<-

And how do the centering controls do anything different to resetting the Arduino on the reset button.

There's a lot I don't understand about this project, this is becoming more and more obvious, may be I should read through the entire thread again to see if there's anything different I can do.
I meant end points.

Yes you can use rest to center it , but Dennis made a fast switch for that.

Also don't forget to press "set offset to 0" button before recalibrating.

I am kind of new to this just as you.

There must be someone more exprianced here to help you out.

My HT worked for the first time, so i did not go deep....

Did you read help, in the config tools?

Gábor
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Old Nov 23, 2012, 11:44 AM
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Sorry guys, I have been crazy busy lately and also have a few other projects, that I would love to get done.

It seems like the calibration-procedure and faulty hardware have been causing some problems.

A few notes...
- The calibration don't have to be done in any specific order
- Magnetometer calibration should be more or less self-explaining from the pictures. It's a bit misleading that the headtracker is turned upside-down on the pictures, but it doesn't matter for the purpose of calibration. It's recommended to keep a good distance from anything metal (mobile-phones are also a bad idea to have nearby), but as it only accounts for offset with this procedure, it shouldn't matter too much (the gain as calibrated with some self-test)
- The accelerometer calibration is different from the magnetometer-calibration. The procedure is found in "Help -> How to" (year, it's well hidden)..

Now, for the sake of calibration. When doing a new calibration, it's important to press "Set offset to 0". Make the necessary measurements, and press save. When this is done, you can check the calibration-data. Don't press "set offset to 0", but just repeat the measurements. The result should be very close to x, y and x offset at 0. If this is true - the offset have been set right

Quick GUI explanation

PPM channel
Controls the channel that pan, tilt and roll is assigned to.

Servo
Center:
Sets the center-position of the servo.

End ->
Left (or right) servo end position

End ->
Right (or left) servo end position

Gain
Controls the necessary head-movement to control the servo. The default should be close to 1:1, but most people probably like a little higher gain to get more servo-movement with less head-movement.

Reverse:
Simply check the box to reverse servo-movement for the channel.

Advanced settings
Most people don't have to adjust any of the advance settings, but they do give some more options if needed...

LP filter at tilt/roll/pan
The software includes a lowpass-filter to remove noise etc. As the headtracker uses quite high update-rate, the default 75 % value is almost not noticeably. Low value will give very smooth movement, but very slow response.

Gyro weight.
This value describes how much we thrust the measurement from the gyro. The best sensor to measure head-movements is the gyro, but unfortunately it drifts. To account for the drift we use magnetometer for pan, and accelerometer for roll and tilt. The value is simply a weight-factor describing how much we thrust the gyro. The default 98% means 98% of the next position estimation is calculated based on gyro, and the last 2% is used from accelerometer or magnetometer to account for drift.

Servo parameters...
Servo-center describes the pulse-width in the unit uS/2. Travel adjust min and max describes how much the pulse can vary from the center-position. Be aware that the normal settings will keep a maximum and minimum pulse-time, while these settings will allow anything.
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Old Nov 23, 2012, 11:53 AM
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Originally Posted by AndyOne View Post
I received the Gyro and Arduino nano yesterday and just put it together on the breadboard all seems to work OK.

One question, If I want to use the gyro board vertically can I just swap the roll and pan functions. This looks OK on the scope but I have yet to link it to the Tx and try it using actual servos.

A.
No, the sensorboard must be orientated with the components up. Never got the software updated to support other orientations.

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Originally Posted by don9f View Post
Mine came from DealExtreme and I also had the Pan drifting back to centre until I set the Pan Weight to 100.....then it worked fine. I've just been out for a flight on this gorgeous morning and the HT was working well. Not sure if being set to 100 is right, but it works for me.

I've ordered more parts from the same supplier as yours to make another, this time putting the sensor board on top of the Arduino, to experiment a bit. At the moment my sensor is on my goggles and linked to the Arduino in my pocket with its 6v battery.....want to improve on that.

Cheers Don
By setting pan-weight to 100 it only relies on the gyro for pan and not magnetometer to account for drift. If that works for you - perfect. If you have problems with anything else, that means it's your magnetometer that makes trouble for some reason. If you set pan-weight to 0 (or 1, can't remember), your pan will only use magnetometer. Will give a good indication on what the magnetometer tries to do

Quote:
Originally Posted by AndyOne View Post
If I move a magnet past the fixed sensor the magnetometer seems to move the servo signal without drifting back but is still heavily damped. This leads me to believe the problem is with the accelerometer or the gyro, I'm suspecting the gyro right now.

Have I missed any important posts in this thread which gives some resolution to all this.

A.
If all LP settings is above 50 (in advanced settings) you shouldn't notice any damping/delay. If you turn the headtracker upside-down you might see some weird behaviour like this, as gyro and magnetometer tries to turn different ways.
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Old Nov 23, 2012, 12:28 PM
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Did I read somewhere that the sensor board should have the components at the top.
I have my board mounted as in the picture in the magnetometer cal screen, I assumed this to be OK but it seems at odds with original statement as it clearly shows the top (component side) of the sensor board as at the bottom.

A.
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Old Nov 23, 2012, 01:40 PM
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Unfortunately the sensorboard must be placed in the right orientation. If you can please try and see if this solves the problem.
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Old Nov 23, 2012, 02:03 PM
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Already done and it seems like success, that's all it was, I was confused by the pictures.

Many thanks,

Andy.
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Old Nov 23, 2012, 02:39 PM
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OK I think I have it now these are the settings I ended up with. I figured out what Don9f meant by setting the pan weight to 100% and this also works for me it's much more consistent than a setting of 98%.

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Old Nov 23, 2012, 02:40 PM
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Quote:
Originally Posted by AndyOne View Post
OK I think I have it now these are the settings I ended up with. I figured out what Don9f meant by setting the pan weight to 100% and this also works for me it's much more consistent than a setting of 98%.

A.
Have you checked the drift on pan with gyro-weight at 100%?
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Old Nov 23, 2012, 03:01 PM
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Dennis,

It does drift a bit but only after some movement, if I leave it still it has zero drift, would it be better to take it back down to 98%.

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Old Nov 23, 2012, 03:12 PM
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Im glad these last few posts have appeared, as I understand things a bit better now.....I knew I'd read somewhere about the implication of setting the 100% value but couldn't just find it earlier.

Cheers Don
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Old Nov 23, 2012, 03:13 PM
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It seems to be a bit of a trade off between some cross talk between pan and tilt at the lower settings and drift at the higher settings. I'll try 99%.

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