Monowheels are nothing new, first being patented in the middle of the 19th century, but never really went mainstream due to, well, quite a lot of obvious issues. We’ve got problems with forward visibility, stability, steering, especially at speed, and the hilariously-named ‘gerbiling’ where the rider can spin around inside the wheel akin to a gerbil in a wheel. Fun times! But obviously that didn’t stop [The Q] from adding to the monowheel corpus by building one out of wood.
Sometimes people take on these projects simply for a laugh, like this bright orange one we covered a while back. Sometimes they’re powered by a motor, be it electric or internal combustion. Some are hand-cranked, some are pedal-powered, its all been tried.
[The Q] is no stranger to interesting wooden builds, and this video from a year ago shows him building a very simple direct-pedal-drive monowheel. The vast majority of the structure is wood, glued and screwed the old-fashioned way, with a bit of metalwork where necessary. We particularly like the simple counterweight solution which doubles up as a parking brake. It may look a little ungainly, but we can’t think of a simpler solution that would make much sense.
The build video after the break is six and half minutes of well executed videography for your viewing pleasure.
Self-balancing robots have become a common hobby project, and they usually require two wheels to work. [James Bruton] has managed to single wheel balancing robot by adding gyroscopic stabilization.
[James] has done other self-balancing robots, like his Sonic robot, but recently started experimenting with gyroscopic stabilization. In that project, he proposed the idea of combining the two stabilization methods to create a monowheel robot, and he followed through on that idea. The wheel is powered by a brushless motor and is stabilized conventionally around the wheel’s axis. Side to side balancing is achieved using a phenomenon known as gyroscopic precession, by tilting a pair of heavy spinning wheels. This is not to be confused with reaction wheels, which use rotational inertia for control. It appears the actuating the gyroscopes also affects the front-to-back stabilization, so at the moment the robots won’t stay on one spot. [James] plans to implement a second observation controller in software to solve this.
Another challenge with this robot is that it cannot turn at the moment. The gyroscopes are not in the correct orientation to effect rotation around the vertical axis, and changing their orientation would cause other problems. A fan, which works like a helicopter’s tail rotor is one option, and a reaction wheel on top might also work. We’re partial to the reaction wheel idea. Having a different mechanical control mechanism for each axis would make it quite an interesting robot.
Multirotor aircraft enjoy many intrinsic advantages, but as machines that fight gravity with brute force, energy efficiency is not considered among them. In the interest of stretching range, several air-ground hybrid designs have been explored. Flying cars, basically, to run on the ground when it isn’t strictly necessary to be airborne. But they all share the same challenge: components that make a car work well on the ground are range-sapping dead weight while in the air. [Youming Qin et al.] explored cutting that dead weight as much as possible and came up with Hybrid Aerial-Ground Locomotion with a Single Passive Wheel.
As the paper’s title made clear, they went full minimalist with this design. Gone are the driveshaft, brakes, steering, even other wheels. All that remained is a single unpowered wheel bolted to the bottom of their dual-rotor flying machine. Minimizing the impact on flight characteristics is great, but how would that work on the ground? As a tradeoff, these rotors have to keep spinning even while in “ground mode”. They are responsible for keeping the machine upright, and they also have to handle tasks like steering. These and other control algorithm problems had to be sorted out before evaluating whether such a compromised ground vehicle is worth the trouble.
Happily, the result is a resounding “yes”. Even though the rotors have to continue running to do different jobs while on the ground, that was still far less effort than hovering in the air. Power consumption measurements indicate savings of up to 77%, and there are a lot of potential venues for tuning still awaiting future exploration. Among them is to better understand interaction with ground effect, which is something we’ve seen enable novel designs. This isn’t exactly the flying car we were promised, but its development will still be interesting to watch among all the other neat ideas under development to keep multirotors in the air longer.
Since Back To The Future II first screened back in 1989, people have been waiting for hoverboards to become reality. Instead, we got a dangerous two-wheeled contraption going by the same name. Wanting something a little cooler, [Bartek Plonek] decided to convert his to a one-wheel design. (Video, embedded below.)
The hack starts by machining the hub motors of the hoverboard. They’re bolted together, and used as the hub of a single larger wheel. Care is necessary to avoid cracking the motor housing during this process, as [Bartek] found during his first attempt. The wheel is then fitted to the centre of a steel frame, upon which two halves of a skateboard are attached to act as a footplate. The original hoverboard controller is still used; we’d love to know if firmware modification was required to work with the new motor configuration.
There will always be those of us who yearn for an iron steed and the wind through your hair. (Or over your helmet, if you value the contents of your skull.) If having fun and turning heads is more important to you than speed or practicality, [Make it Extreme] has just the bike for you. Using mostly scrapyard parts, they built a monotrack motorcycle — no wheels, just a single rubber track.
[Make it Extreme] are definitely not newcomers to building crazy contraptions, and as usual the entire design and build is a series of ingenious hacks complimented by some impressive fabrication skills. The track is simply a car tyre with the sidewalls cut away. It fits over a steel frame that can be adjusted to tension the track over a drive wheel and a series of rollers which are all part of the suspension system.
Power is provided by a 2-stroke 100cc scooter engine, and transmitted to the track through a drive wheel made from an old scuba tank. What puts this build over the top is that all of this is neatly located inside the circumference of the track. Only the seat, handlebars and fuel tank are on the outside of the track. The foot pegs are as far forward as possible, which helps keep your center of gravity when stopping. It’s not nearly as bad as those self-balancing electric monocycles, but planning stops well in advance is advisable.
While it’s by no means the fastest bike out there it definitely looks like a ton of fun. Build plans are available to patrons of [Make it Extreme], but good luck licensing one as your daily driver. If that’s your goal, you might want to consider adding a cover over the track between the seat and handlebars to prevent your khakis from getting caught on your way to the cubicle farm.
Monowheels are a singular form of transport. Like electric scooters and the Segway, they are remarkably impractical for getting from point A to point B, are expensive to build or buy, and make you look faintly silly as you ride them down the street. However, we’d be hard pressed to find a member of the Hackaday team that wouldn’t at least want a go on one for half an hour. [MakeItExtreme] felt the same way, and built one of their own.
The build starts with a tube bender, used to form 40mm tubing into a continuous circle to form the main wheel. Teflon is then turned to produce several rollers that interface the main wheel to the inner frame. Several small motorbike tyres were cut apart to create the tread to provide some decent grip. Power comes courtesy of a 110cc four stroke engine, allowing this thing to go just fast enough to get the rider seriously injured in the event of an accident. The team reports stability is poor at low speed, but remarkably good once above 30 km/h.
[Jason]’s at it again. This time the LEGO maestro is working on a LEGO BB-8 droid. As a first step he’s made a motorized monowheel that not only races along hallways and through living rooms at the peril of any passing people, but turns as well.
To drive it forward there’s an axle that runs across the center of the wheel and a motor that rotates that axle. He’s also included some weight bricks. Without the mass of those bricks for the rotation to work against, the motor and axle would just spin in place while the friction of the floor keeps the wheel from rotating. If you’ve seen the DIYer’s guide to making BB-8 drive systems, you’ll know that this is classified as an axle drive system.
For steering the monowheel left or right he has another mass located just above the axle. Shifting the mass to the left causes the monowheel to lean and move in that direction. Shifting the mass to the right makes the wheel move to the right in the same fashion. Being ever efficient, [Jason] has the motor that shifts the mass doubling as the mass itself.
As with any proof-of-concept, there are still some issues to work out. When turning the wheel left or right it can tip onto its side. Ridges on both sides of the wheel’s circumference reduce the chances of that happening but don’t eliminate it altogether. Also, the steering mass/motor doesn’t yet have a self-centering mechanism; after a turn it’s up to the person holding the remote control to find center. If the mass isn’t correctly centered after a turn, there tends to be some wobble.
As always, we’re looking forward to seeing how [Jason] solves those issues but first he’ll have to put it back together since, as you can see from the video below, it didn’t quite pass the stair test.