Robot writes with its feet


Last week it was demonstrated how naminukas can act as 4DOF pick and place arm. This week I finished making a detachable tool mechanism. Goal was to allow robot arm to use different tools without adding any additional actuators to minimise complexity. Idea was to exploit the fact that in many cases robot arms don't utilise their full possible workspace. Putting tools in these "unused" areas allows robot arm itself to be used as actuator to attach/detach tool to arm.

I experimented with various sliding, snapping and magnetic ways to attach tool to arm and came up with a hybrid sliding and magnetic design. Here is a demonstration of mechanism in action:

While detachable tool mechanism was made specifically for naminukas it is generic enough to be applied to any robot arm so I will explain in more details how it works:

All parts were printed in PLA. Magnets used are 4x4x15mm. They are held in place by friction by precise sizing of the holes. As mentioned above pins are made of random screws laying around the house:


Getting arm/foot to pick and return tool reliably took quite a few trial and error cycles. These are all 3D printed parts which didn't work as expected:

Failed attempts
4DOF pick and place arm
Read next:
Hanging from the ceiling