Behold The Mega-Wheelie, A Huge One-Wheeled Electric Skateboard

DIY electric personal vehicles are a field where even hobbyists can meaningfully innovate, and that’s demonstrated by the Mega-Wheelie, a self-balancing one-wheeled skateboard constructed as an experiment in traversing off-road conditions.

[John Dingley] and [Nick Thatcher] have been building and testing self-balancing electric vehicles since 2008, with a beach being a common testing ground. They suspected that a larger wheel was the key to working better on rough ground and dry sand and tested this idea by creating a skateboard with a single wheel. A very big, very wide wheel, in fact.

The Mega-Wheelie houses a 24V LiFePO4 battery pack, 450 W gearmotor with chain and sprocket drive, SyRen motor controller from Dimension Engineering, Arduino microcontroller, and an inertial measurement unit to enable the self-balancing function. Steering is done by leaning, and the handheld controller is just a dead man’s switch that disables the vehicle if the person piloting it lets go.

Design-wise, a device like this has a few challenging constraints. A big wheel is essential for performance but takes up space that could otherwise be used for things like batteries. Also, the platform upon which the pilot stands needs to be as low to the ground as possible for maximum stability. Otherwise, it’s too easy to fall sideways. On the other hand, one must balance this against the need for sufficient ground clearance.

Beaches are rarely covered in perfectly smooth and firm sand, making them a good test area.

In the end, how well did it work? Well enough to warrant a future version, says [John]. We can’t wait to see what that looks like, considering their past 3000 W unicycle’s only limitation was “personal courage” and featured a slick mechanism that shifted the pilot’s weight subtly to aid steering. A video of the Mega-Wheelie (and a more recent unicycle design) is embedded just below the page break.

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Homebrew Biped Bot Shows Off Some Impressive Moves

We’ve seen enough DIY robotic platforms here on Hackaday to know that most of them take the literal and figurative path of least resistance. That is, they tend to be some type of wheeled rover. But of course, there are plenty of other forms of locomotion, should you want to take on something a bit more challenging.

This biped robot from [Tast’s Robots] is a perfect example. While it’s still technically wheeled, its self-balancing nature makes things quite a bit more complex. It doesn’t just stand upright either, it also has a unique ability to crouch down by rotating its motorized knees and hips. As demonstrated in the video below, it can even navigate relatively uneven terrain — pulling off such a smooth transition between hardwood and carpet is no easy feat for a self-balancing bot like this.

But the best part? It isn’t just fully open source, it’s also designed to be built with only the tools and capabilities available to the average home gamer. That means 3D printed components, wooden dowels, and RC car parts. Even the power supply, a Ryobi 18 V tool battery, is easy to source and relatively hacker friendly.

Just as impressive as the hardware is the suite of software packages developed to handle things like balancing, locomotion, and reverse kinematics. Each one is maintained and documented as their own individual Apache-licensed projects, making them far easier to utilize than they would be if it was all implemented as one monolithic system.

If you really want to ditch the wheels, we’ve seen a few biped walkers in the past. But frankly, none of them can compare to the capabilities and scope of this project.

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Can You Cheat At Tightrope Walking?

Tightrope walking is no mean feat — it takes years to master (even with a balance rod) — but that’s too much like hard work for [James Bruton]. Obviously, the solution is just a matter of the application of some electronically-controlled balancing technology, and [James] is just the guy for the job. Bearing a passing resemblance to a cross between a prop from Ghostbusters and a medieval torture device, this weighty balancing cheat device almost kind of works!

On a slightly more serious note, bipedal balance is a complex problem to solve. You have multiple limb sections, which can move independently in many ways, as well as the upper body also contributing to shifting around the center of gravity in a hard-to-predict way. So it’s no great surprise that a simple torque reaction device strapped to the torso doesn’t help a great deal, but it sure is fun to watch him trying. The bottom line is this — our bodies are pretty heavy, and the amount of force needed to correct tilt in the plane of interest is hard to generate without the reaction wheel itself being really heavy, and that extra mass doesn’t exactly help with the overall balancing problem. We reckon the overall concept is sound, it’s just that all those extra limbs flopping around make this simplistic sensing and compensation strategy only partly effective.

Stabilizing small robots is probably a bit easier than a human, such as this gyroscopically-stabilized monowheel, but sometimes you don’t even need the gyroscope, as you can control the driving wheels directly.

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Self Balancing Robot Needs A Little Work

A self-balancing robot isn’t a new idea, but we liked the aesthetics of [Maker ATOM’s] build. The use of a breadboard and a printed bracket looks good, as you can see in the video, below.

Like most first-time projects, though, there were some lessons learned. The power supply needs a little work and the range of balance compliance didn’t meet expectations. But those problems are soluble and, as usual, you often learn more from working through issues like these.

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A Self-Driving Bicycle Is Something To Marvel At

One of the most annoying things about bicycles is that they don’t stay up on their own, especially when they’re stationary. That’s why they come with stands, after all. That said, if you had plenty of advanced electronic and mechanical equipment fitted to one, you could do something about that, and that’s just what [稚晖君] did.

The video of the project comes without subtitles or any translation, but the gist of it is this. A reaction wheel is fitted to the seat tube, along with a motor which can turn the handlebars via a linkage attached to the head stem. There’s also a motor to drive the bicycle forward via a friction drive to the rear wheel. Combine these with an inertial measurement unit and suitable control system, and you have a bike that can balance while standing perfectly still.

The performance of the system is impressive, and is even able to hold the bike perfectly upright while balanced on a fence rail. Thanks to an onboard camera and LIDAR system, the bike can also drive itself around with no rider on board, which is quite a spooky image. Find a way to do the same while hiding the extra mechanics and you’d have one hell of a Halloween display.

Similar projects have been attempted in the past; we featured a self-balancing bike built as a university project back in the distant past of 2012. Video after the break.

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Building D-O, The Cone Face Droid

For many of us, movies are a great source of inspiration for projects, and the Star Wars films are a gift that just keeps giving. The D-O droid featured and the Rise of Skywalker is the equivalent of an abandoned puppy, and with the help of 3D printing, [Matt Denton] has brought it to life. (Video, embedded below.)

D-O is effectively a two-wheeled self-balancing robot, with two thin drive wheels on the outer edges of the main body. A wide flexible tire covers the space between the two wheels, where the electronics are housed, without actually forming part of the drive mechanism. The main drive motors are a pair of geared DC motors with encoders to allow closed-loop control down to very slow speeds. The brains of the operation is an Arduino MKR-W1010 GET on a stack that consists of a motor driver, shield, IMU shields, and prototyping shield. [Matt] did discover a design error on the motor driver board, which caused the main power switching MOSFET to burst into flames from excessive gate voltage. Fortunately he was able to work around this by simply removing the blown MOSFET and bridging the connection with a wire.

The head-on D-O is very expressive and [Matt] used four servos to control its motion, with another three to animate the three antennas on the back of its head. Getting all the mechanics to move smoothly without any slop took a few iterations to get right, and the end result looks and moves very well. Continue reading “Building D-O, The Cone Face Droid”

Pop A Wheelie With Your Electric Skateboard, The Hacker Way

Using a bit of tech to make up for a lack of skill is a time-honoured tradition, otherwise known as cheating among those who acquired the skill the hard way. Learning to wheelie manual a skateboard is usually paid for in bruises, but [blezalex] got around that by letting his electric skateboard handle the balancing act.

At first glance the board looks and rides like an average DIY electric skateboard, with an off-the-shelf  a dual hub motor truck, VESC speed controllers and a wireless throttle. The party trick appears when the front wheel is popped off the ground, which activates the secret self-balancing mode. At this point a STM32F401 dev board and MPU-6050 IMU take over control of the motors, which is in turn controlled by leaning forward or backwards, like a hoverboard. The remote throttle turns into a dead man switch, which cuts power to the motors when released.

[blezalex] says he has had less that an hour of skateboard time in his life before getting on this one, which is a good testament of just how well it works. The biggest challenge was in getting the board to turn while on two wheels, which was solved by sensing side-to-side tilt of the board with the IMU and applying proportional differential torque to the wheels. With a bit of practice it’s also possible to smoothly shift between riding modes while moving.

We think this is a really elegant cheat, now we need to build one of our own. Fortunately the STM32 firmware and instructions are all up on GitHub. Building your own electric skateboard has become really simple with the availability of off-the-shelf components. We’ve also seen a bicycle with a wheelie cheat device to prevent you falling on your back