British YouTuber James Bruton has plenty of experience with self-balancing technology and omnidirectional wheels, having already built a self-balancing bicycle using a sideways-mounted omni-wheel, as well as a heap of self-stabilizing robot projects.
Indeed, this isn't even his first crack at an omnidirectional motorcycle, having released a video some seven months ago showing how he'd put a large Omni-Wheel at either end of a frame and successfully built a self-balancing electric moto. Well, the self-balancing part was successful, and he was able to turn it around and move side to side without issue, but it wasn't capable of moving forward or backward.
And thus, the Screw Bike. For this latest iteration, Bruton moved from Omni Wheels to Mecanum-styled wheels – the difference being that the Omnis have their rollers mounted sideways, where a Mecanum wheel places them at diagonal angles.
While the rollers are free-spinning, the wheels themselves are driven. And a vehicle with four Mecanum wheels can, by controlling the speed and direction of these four wheels, move in any direction, or spin merrily on the spot.
Bruton built his own 360-mm (14.2-inch) diameter Mecanum wheels for the Screw Bike, 3D-printing many of the components – there was nothing this size available off the shelf, and even if he was willing to use something a full third smaller, the options were hideously expensive.
He mounted these four wheels sideways, since their primary job most of the time is to quickly self-balance the chassis. Each is driven by a toothed rubber belt, connected to an electric motor and thus capable of driving forward or backward as needs be.
A set of rigid handlebars, a bench seat and a charmingly dorky headlight later, the Screw Bike was up and running. Once turned on, it balances patiently in place, and with a rider on board it does much the same thing. Like a Segway, you can lean it left or right to initiate motion in either direction.
A twist throttle allows the bike to be driven forward, without cancelling out its self-balancing ability. A switch on the bars lets you put it in reverse and go backwards as desired, and a separate set of controls allow the rider to spin the bike in place.
"This feels amazing," said Bruton on his first indoor test ride, somehow managing not to crash into anything in his kitchen. He then takes it for a spin in a car park, clearly enjoying this unique machine's very odd capabilities as he spins and glides in all directions.
It doesn't look particularly fast – certainly not when it's moving forward or backward. It's got nothing in the way of suspension, and it'd clearly be a long shot to call this a practical design for mass manufacture. It does, however, look like a bunch of fun and a heck of an achievement for a backyard builder.
Bruton has open-sourced the CAD designs and code for the bike, so the intrepid can build their own Screw Bikes at will. Check it out in the video below!
Source: James Bruton
