Klann Linkage Crab

Klann Linkages are designed to emulate ambulatory systems from nature. They are driven by a single motor and generate a gate that can be used to make a robotic walker. I first came across these several years ago (2012 I think) and I found them fascinating. Following some living hinge design work at Ekso I decided to design my own little walker. Though originally designed to be a modular leg system I believe I've gotten it as far as I needed to satisfy my curiosity.

A little rough layout work allowed me to get the motion I wanted. Which is sort of a tarantula gait. Now it was time to figure out how to make a modular robot with living hinges for this. I opted for a single piece leg design shown below. This allowed me to make the legs rather thin and eliminate the need for bearings or bushings. I overlaid this with the pin joint version to visualize my idea.

The black component rides in two bearings which are shown in a light gray. This part has a groove for an o-ring style belt that would drive the two legs nearest it with pins in single shear. So in total we have something like 15 parts per module (2 legs). Two leg plates, two pins to drive them, two small bushings for those pins to ride in, the central wheel, two bearings for that wheel, the main plate that separates the legs, two sheet metal or acrylic plates on the ends to sandwich it all and three screws. Not bad for two five bar mechanisms, eh? Next up is figuring out how to machine them and check for clearances around the hinges.