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Dynamixels And Herkulex.Again

Love digging up a horse and beating it again? Well fellas I'm here to help you out!

Lets start another up to date discussion about the use of, and the support of, Dynamixels and the HerkuleX line of professional servos. I'm moving up a level with some upcoming projects and steering away from the hobby style servos. I've spent days researching, using geared stepper motors, geared DC motors as servos and have come back full circle to serial servos. Due in part, by all the unknowns and unreliability associated with creating a servo from scratch.

Tell me about your success and failures of using the Dynamixel and HerkuleX servos with EZB. Please be detailed in your experience and add something to what is already written in the prior threads about subject. What needs to change/improve for better support? Perhaps this is adding to existing plugins or writing new ones? Speaking of plug ins (this is probably another topic), but i wonder if there would be more incentive to create plug ins if there was a pay for development? Like how the app store works? Just a thought there.

I really believe in everything EZ robot and want to continue using the products, because well its so EZ and the results are amazing. I'm well aware the majority of sales is in the education market for EZ Robot and therefore guides their company. But, how can we work together as a group to build support for the next level of servos and professional robotics? And ask ourselves what is the motivation to do so?

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PRO
Synthiam
#111  
Correct - the IoTiny does not have a hardware uart.

The plugin can be modified to use one of the digital pins, however. The only limitation would be the max baud of 115,200. That baud should not be a problem, as it's still considerable Fast and actually will be more reliable than the default 1,000,000bps of some dynamixel servos. The 1mbps actually has quite a bit of frame errors in my testing IF data lines are routed near devices causing electrostatic interference (i.e. Motors and high frequency CPUs or power supplies).
PRO
USA
#112  
Got it, thanks DJ!
PRO
USA
#113  
One request, now that I'm dealing in 4096 positions, any chance you can create an additional input (ARC, not the plug in) to go with the arrow and drop down for inputting min and max positions. Just to type in the position in a field?
#114  
One thing I noticed, and it is no fault of ez robot, is .. that due to these servos not having a physical stop in them it sometimes makes " homing" very difficult. What I think is happening is that the servos want to go to there " home" position without regard to direction. For example my init script tells both elbows to rotate home, and up so the arms don't get run over by its treads. During power down the arms fall to the ground. If the elbows rotate outside of the tread ,the next time powering up the elbow tries to spin backwards effectively trying to beat himself. So basically I just make sure both arms are in a " parked" position where gravity can not affect position during power off.
PRO
USA
#115  
Interesting. That could make for some serious accidents in some cases. How are you keeping your arms in a certain position in power off? Do these servos roll back with no power under load? Like your arms slumping down. How much load are on them?
#116  
Yes exactly arms slumping down. What I did was change the angle of the shoulder joint forward so when elbow joint is in it's up position the lower arm rests on top of the upper arm, kind of.
PRO
USA
#117  
Got it. I'll have to do some testing on that. Could be dangerous the bigger my servos get.. watch the video from trossen where they break chicken bones with dynamixels.
#118  
Hahaha...don't be a chicken and post the link!

Great to hear you got some cool stuff to come in 2017!
Looking forward to see what you are up to...

I am waiting for my 3D printer being shipped to get stuff going...
*superexcited*:D
PRO
Synthiam
#120  
That's disgusting. I modified your post so it doesn't show up as a preview video in the news feed.
PRO
USA
#122  
@Dj, good idea.

But does demonstrate the importance of how powerful these servos are! Use caution to keep from maiming yourself !
#123  
@fxrtst - so how did your Dynamixel project work out?
PRO
USA
#124  
It's still n progress. It will develop over the next couple of months. But so far I love the high resolution. Even without the feedback, it's a superior servo for large projects.
PRO
USA
#125  
@dj,

I don't want to create another thread as this is still on topic. Do virtual servos support invert direction? I can seem to get a dynamixel to invert on the camera panel.
PRO
Synthiam
#126  
I don't think so. I'll have to look at the plugin code and see
PRO
USA
#128  
Couple of things. Just got my MX 64ATs and updated to the newest version of ARC. Now not sure if it's coincidence but I can't get the dynamixels to move anymore. Could anyone one with this set up confirm the plug in is still working. I'm up to date with the plug in as well. Tried with both my new dynamixels and my mx28. Nothing at all.

So many variables in this set up want to rule out broken plug in first before I run down thru the list.
PRO
Synthiam
#129  
Check baud rate on servos.
PRO
USA
#130  
Yeah I did thanks. Was actually computer wasn't updating comm ports and using a burnt up a dynamixel (ouch! $$$$)! So a perfect storm of issues..

I switched laptops and new dynamixel and working again!

Also dynamixels do invert direction as talked about above thread! Yay.