Simple 3D Printed Robotic Arm Uses Compliant Mechanism

Learning through play is effective for humans of all ages, and since 2016 [slantconcepts] has been designing STEM kits that help teach kids to build their future overlords. They are launching version 3 of their LittleArm robotic arm, and the progression from version 1 is an interesting study in simplification and parts count reduction without sacrificing functionality.

In all of the LittleArm versions the main mechanical components are 3D printed, and driven by 3 servos for motion plus one additional servo to run the gripper. These kits are specifically intended to be built and disassembled repeatedly, and classrooms are a great place for small screws to easily disappear, so reducing the number of screws was a big goal for v3. The gripper/forearm shows the most dramatic improvement from the previous versions, being simplified from 8 separate components to a single 3D printed part by using a compliant mechanism — that squiggly pattern that allows the gripper to flex into place. The gripper tips also feature a simple “cutout” that allow it more easily grasp horizontal objects.

An Arduino Nano based expansion board is used to control the arm, with a HC-06 Bluetooth module to allow it to be controlled via a smart phone app. Various sensors can also be added to expand the kit’s capabilities. Unfortunately the mechanical design is not open source, but it can still be a source of inspiration for your own design projects.

Hopefully this kit will inspire some future hackers to build a more advanced 3D printed version, or even a giant hydraulic powered arm.

5 thoughts on “Simple 3D Printed Robotic Arm Uses Compliant Mechanism

  1. I had hopes that “compliant” meant they found a cheap actuator (servo) that could be overpowered without damage. Replacing a hinge with a soft bit of plastic is a disapointment, by comparison.

  2. Very cool little robot. It looks like a lot of work was put into making construction simple but still having a capable robot for kids to learn on. Is the smart phone control only for Android? I don’t think iPhones will pair with the older profile used by HC-06.

Leave a Reply to Grumble Cancel reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.