An In-Depth Look At Dexter, The Robotic Arm

Dexter, a really great robot arm project, just won top honors in the 2018 Hackaday Prize, and walked away with $50,000 toward continuing their project. As a hat tip to Hackaday and the community, Haddington Dynamics, the company behind Dexter, agreed to open-source their newest version of Dexter as well. As James Newton said when accepting the trophy during the award ceremony, “because of your faith in us, because of this award, we have been moved to open-source the next generation of Dexter.” Some very clever work went into producing Dexter, and we can’t wait to see what further refinements have been made!

Dexter isn’t the only robotic arm in town, by any means. But in terms of hobbyist-level robotics, it’s by far the most complete robot arm that we’ve seen, and it includes a couple of design features that make both its positional accuracy and overall usability stand out above the rest. This is a robot arm with many of the bells and whistles of a hundred-thousand dollar robot, but on a couple-thousand dollar budget. Continue reading “An In-Depth Look At Dexter, The Robotic Arm”

A Peek At The Mesmerizing Action Of A Cycloidal Drive

Cycloidal drives are fascinating pieces of hardware, and we’ve seen them showing up in part due to their suitability for 3D printing. The open source robot arm makers [Haddington Dynamics] are among those playing with a cycloidal drive concept, and tucked away in their August 2018 newsletter was a link they shared to a short but mesmerizing video of a prototype, which we’ve embedded below.

A 10:1 Cycloidal Drive [Source: Wikipedia, image public domain]
A cycloidal drive has some similarities to both planetary gearing and strain-wave gears. In the image shown, the green shaft is the input and its rotation causes an eccentric motion in the yellow cycloidal disk. The cycloidal disk is geared to a stationary outer ring, represented in the animation by the outer ring of grey segments. Its motion is transferred to the purple output shaft via rollers or pins that interface to the holes in the disk. Like planetary gearing, the output shaft rotates in the opposite direction to the input shaft. Because the individual parts are well-suited to 3D printing, this opens the door to easily prototyping custom designs and gearing ratios.

[Haddington Dynamics] are the folks responsible for the open source robot arm Dexter (which will be competing in the Hackaday Prize finals this year), and their interest in a cycloidal drive design sounds extremely forward-thinking. Their prototype consists of 3D printed parts plus some added hardware, but the real magic is in the manufacturing concept of the design. The idea is for the whole assembly to be 3D printed, stopping the printer at five different times to insert hardware. With a robot working in tandem with the printer, coordinating the print pauses with automated insertion of the appropriate hardware, the result will be a finished transmission unit right off the print bed. It’s a lofty goal, and really interesting advancement for small-scale fabrication.

Continue reading “A Peek At The Mesmerizing Action Of A Cycloidal Drive”