RoboSavvy Forum

Open Ax12 Dynamixels

2011-01-17T02:57:10+01:00

Can anyone show with photos how to change axis inside Dynamixel mechanically ?

Statistics: Posted by MOHIT JINDAL — Mon Jan 17, 2011 2:57 am

axis range change

2011-01-16T23:58:42+01:00

Unfortunately the deadzone sector is dependent on the servo construction.

Yes the servo contains a DC motor and also a rotating variable resistor. In position hold the servo tries to keep the resistance of the variable resistor at a constant value to match the position value as set by the user.

One bad thing: This variable resistor may get a little noisy with servo age which would cause the servo to be a little jumpy. I think some user on this forum was once swapping out the variable resistor for a magnetic hall effect sensor and then placing a tiny magnet on the output shaft, this was all inside the servo and would give a solid state position encoder that would never wear out.

Statistics: Posted by Fraser — Sun Jan 16, 2011 11:58 pm

axis range change

2011-01-15T21:03:46+01:00

problem solved.. mechanically, but it is very interesting: can we move the deadzone, or it is dependent on servo construction?
just one more question: how servo can set the position? is in AX-12 some encoder?
sorry if that question is stupid, but i don't know a lot of electronics, just know that in ax-12 is some DC motor?
HOW DOES IT WORK?

Statistics: Posted by nodobra — Sat Jan 15, 2011 9:03 pm

axis range change

2011-01-15T19:59:28+01:00

Hi, The AX12 servo can be used in continuous rotate mode for wheeled robots. But the potentiometer has a "deadzone" where all readings are zero. So ordinary servo operation (where servo holds position) can only be used outside of this deadzone.

I have found that the deadzone for the potentiometer is only ~30 degrees. Which gives a real useable range of ~330 degrees. But I am not sure if you can access all 330 degrees with standard firmware?

Maybe the dynamixel specs quote 300 degrees as a conservative value that all servos are definitely capable of?

Statistics: Posted by Fraser — Sat Jan 15, 2011 7:59 pm

axis range change

2011-01-15T17:54:05+01:00

hello
is it possible to change range of ax-12?
i want to use also 300 degrees, but not in these positions, that we have as a firmware settings.
?

Statistics: Posted by nodobra — Sat Jan 15, 2011 5:54 pm