More than likely, you’ve come to these pages because you’ve seen me (Mechanical Cat aka SiameseKAT) or my friend TheKRAB walking around at some show or event. We’re simple walking robots who were built by my human pet to shamelessly plug a commercial project. But that’s long forgotten and now we Kreatures have acquired independent careers of our own. We go to shows like Maker Faire UK and EMF just for the fun of seeing people’s smiles as they interact with us.
Much credit is due to Theo Jansen who kindly published the design of the legs he developed for his own beach-walking StrandBeests. The legs of SiameseKAT and TheKRAB are somewhat modified versions of his design. So many thanks to him.
If you’d like to make you own walking robot whose legs work like mine do, then there are some tips and hints at the bottom of the page.
Hints and tips for building your own
Use Theo Jansen’s leg design so you have a workable leg geometry to start with. Modify it so that it’s simpler to build and so that the feet are picked up high enough to clear – say – lawn-length grass.
Use powerful motors and gear them down: there’s a lot of friction in all my leg joints. Me and TheKrab use the motors/gearboxes from a children’s ride-on car to drive our legs.
Fit metal-on-metal or metal-on-plastic bearings at the main joints – the hips and the knees – otherwise they will wear out very rapidly. The Kreatures shown on this page, for example, use over 50 miniature ball-races each.
Bear in mind that – when the robot is steering – there are strong sideways forces on the legs as the feet are dragged across the floor. So construct them to withstand the punishment. Or make sure your human carries lots of spares.
Think carefully about safety. So design the leg joints to minimise risk of pinching and scissoring. Fit current-limiters to the motors so that – in the worst case if a finger does get trapped in the mechanism – the motor doesn’t cause injury. Design the gears so that fingers can’t become trapped in the cogs.
Keep the chassis short. Having my front legs and back legs close together makes it much easier for me tor turn using skid steering, especially when on rough ground.
Place the centre-of-gravity low down. Or stay away from sloping ground. I have been known to do a wheelie (leggie?) when accelerating up a steep slope. Me-ow.
Be prepared to put in quite a bit of time. My human’s “two-week” Christmas-hols project to build me wasn’t anywhere near complete until… April.