Replies to This Discussion

Permalink Reply by Michael Pursifull on June 24, 2012 at 7:06pm

ah.... no.

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Permalink Reply by Michael Pursifull on June 24, 2012 at 7:06pm

http://www.google.com/search?client=safari&rls=en&q=pwm+con...

This one is better. 

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Permalink Reply by James Printer on June 24, 2012 at 7:18pm

Ah wow thanks Mike. :)

Also currently trying the mod to make the servo into a simple continous rotation motor, with any luck running it directly from 6V could do the trick.

If I have a continous rotation servo, and run it off a PWM controller, would it maintain the same speed even if the battery runs down a little? I'm thinking it wouldn't, as the PWM tells it 'how much of maximum speed and which direction' to run.

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Permalink Reply by Michael Pursifull on June 24, 2012 at 7:26pm

There are three lines into a servo, not two.
Use a regulated power source.

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Permalink Reply by James Printer on June 24, 2012 at 7:47pm

I don't believe I said there were two.

Ok will look at regulated power sources.

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Permalink Reply by Fabien Bruning on June 27, 2012 at 8:11am

You can get relatively cheap optical encoders (about 30$) that give your Arduino the rotational speed. Simply take the desired speed, subtract the current speed and multiply that by some suitable constant. Output that to PWM and it should work. (the most basic PID controller is this)

If you want it really cool you could probably use some diodes and a voltage regulator to create a burshless power transmitter, but the slip ring would be a lot easier I think.

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Permalink Reply by Shyam Balasubramanian on November 3, 2012 at 7:41pm

Dear All,

I am using continuous rotation servo for 'Yaw' control of my camera gimbal. I am using it for stabilization around a setpoint/ target angle, using PID's.

If I give a target of say 60 degrees, the servo should adjust its speed in such a way as to make it to 60 degrees (in a circle of 360 degrees).

The AHRS system gives a DCM Yaw output from [-180 to 180], i.e. 0 to +180 degrees and sudden transition to -179 and goes to 0 in the reverse direction.

The problem I am facing is this transition around the boundary from +180 to -179. If my target angle is say 170 degrees, once it nears 170 degrees the servo speed reduces and when it reaches 170, the velocity becomes zero to a standstill. Having the same 'Target angle' if the orientation of board is such that yaw output is 180 and then a slight change in orientation cause a sudden change to -179 (This is a difference of almost 180 - (-179) ~= 360). The servo speed reverses from relatively slow to fast, due to this vast difference to compensate.

Is there a workaround? or a method to compensate for this problem? This is not there in the code. Any help is appreciated.

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