Seeking ideal motor for a powered exoskeleton elbow joint

[Ikonoclasm]

Hey there,

I’m a senior computer engineering student, and I’ve decided to delve into the world of robotics design. While the electrical control and programming aspects are well within my wheelhouse, my mechanical engineering knowledge is limited to the basics.

Specifically, I am attempting to fulfill the ultimate nerd dream - an iron man suit, that is to say, a powered exoskeleton. I understand that this will be a long term, time consuming, expensive project. I’m starting small - the elbow joint, with sheaths around the forearm and upper arm.

Currently I’m using a 5202 Series Yellow Jacket Planetary Gear Motor to power a linear actuator connected to my prototype arm frame, which works-ish. I would like very much to switch to direct motor drive, but the yellow jacket is woefully inadequate for this.

Ideally I would like something that can rotate around 60 RPM and has a form factor that will fit around an elbow without being absolutely insane (I.E., either long and thin, for use with bevel gearing, or wide and flat, for directly attaching to the joint) and able to output as many Nm of torque as possible - 30 would be pretty solid, acting on my moment arm of about 30cm, but the more the better.

Any assistance you guys could provide would be greatly appreciated.

[Andre]

What about a hoverboard motor in direct drive mode? They are cheap, easy to get and with up to 400 Watts they have enough power

[towen]

I would probably use something like this:

Opentorque project - new design

Hello all, I wanted to share the new design of the opentorque project with you. The original version was created by Gabrael Levine, more info here. Skyentific had allready made some small improvements, so I started this redesign with his model. The original design uses a very expensive and hard to find cross roller bearing. This is the main reason for the new version, which now only uses cheap bearings. But eventually I have changed allmost every part in this design, and added improvements wh…

A direct-drive torque motor as @Andre suggested could be used, but they are quite difficult to control, and hoverboard motors only have Hall sensors. They are also quite large diameter for a given torque rating, which could be a problem for you. They are also designed for much higher speeds than you would need, so they could be potentially dangerous (break your arm and/or the exoskeleton itself)

So instead, I’d suggest to use a backdrivable gearbox e.g. the above 3D printed planetary.