How to disencumber servos?

mechanics
english
Tags: #<Tag:0x00007fae8a546560> #<Tag:0x00007fae8a546330>

#1

Hey!

I made a robotic arm using 4 Dynamixel AX-12A servos.
During operating it, I noticed sometimes it gets a little cranky, loses fluid movement and starts stepping instead.
My setup looks like this:

I understand that the stepping is because of the lever arm, probably over a longer period of time the force applied to the first horizontally aligned servo (this is the one making cranky movements sometimes) causes it to overheat a little, thus the stepping effect. I use the servos with 30% speed so the movement is a bit more precise, I also lowered torque a little bit (but I can’t make it lower because the servo needs to apply force at the end of the finger).

My question therefore is a little more generic: how can you lower the encumbrance on the servo? I want to eliminate this stepping. I thought of building something similar to a plastic exoskeleton, a couple of frames, but I have no idea how to shift the applied forces at least partially to the frame.


#2

Hi,
I think it is a common issue with AX-12, and as far as I know nobody on Poppy team took time to investigate on that.


#3

Update:

For anyone who might be interested in this topic, I made a quick research in the forums of their USA reseller, and came up with an idea how to dampen this effect. I’m using counterbalancing now, it smoothens out the movement just the amount I needed, and it seemingly doesn’t put far more stress on the servos, they work more reliably than before (touching them feels like it doesn’t heat them that much more).

As you can see, in my case, counterbalancing means that I cable tied a spring to the side of the servo in the direction of the movement (quality engineering, ikr), this way the spring will be extended (would work with compressing it in the other direction too, if I had the tools to precisely fix the spring in position). The movement itself isn’t smoother that much, but the precision is at least increased by a great deal, as the spring always forces the servo to stick to one side of the wiggling.