Annin Robotics AR4, open plan low cost 6DOF desktop industrial robot | Hacker News Reader

Annin Robotics AR4, open plan low cost 6DOF desktop industrial robot

anninrobotics.com

18 pointsdanboarder4 comments

It's stepper motor drive. Limited force feedback, so no doing "cobot" stuff.

Motors remain a headache in low-cost robotics. The good ones with good encoders and controllers cost too much. Steppers don't provide force feedback. Actuators based on R/C servos are too wimpy, usually lack good bearings, and have too much gear reduction.

This isn't fundamental. Brushless drone motors are really good 3-phase motors with good controllers and great power to weight ratios, and don't cost too much. But there's more volume in drones than in low-cost robot arms.

Take a look at what you can get on Alibaba for $3000 to $6000. The Annin thing costs somewhere about $3000, when you add up all the parts kits and consider the cost of 3D printing.

Brushless drone motors suffer from too high a kV (~operating RPM), needing a lot of gear reduction for this kind of application, but I take your point about volume.

Gimbal motors (also in drones) are closer to what is needed, and often come with encoders and centre pass through holes for cables.

Some manufacturers now make larger versions [1] with gearing and a built in motor controller, originally more for robot dogs than robot arms so backlash etc is worse, but the low gear ratio lends itself to cobot type.

For more conventional robot arms (high precision and stiffness) the harmonic drive gearbox patents have expired so there are some [2] of those coming out of china. This offers a really high reduction and very low backlash.

[1] https://www.myactuator.com/product-page/rmd-x8-pro

[2] https://www.myactuator.com/rh-14details

The drone motors are also missing gearboxes, harmonic drives are being knocked off now and coming down in price, that's the real cost difference here, the gearboxes

This is a really cool project, I have been meaning to build one of Annin's arms for a while. They appear to be well engineered and easy to work on, and I really appreciate the fact that many components are available in either a printed version or an aluminum version for when you want to be slightly more professional. I do wish he'd put the code and designs on Github but that's honestly such a minor complaint.

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