Balancing Robots From Off-The-Shelf Parts

In this day and age, we are truly blessed as far as the electronics hobby is concerned. Advanced modules such as gyros and motor controllers are readily available, not just as individual parts, but as pre-soldered modules that can be wired together with a minimum of fuss and at low cost. This simple balancing robot is a great example of what can be done with such parts (Google Translate link).

The robot has an ESP32 running the show, which provides both the processing power required, as well as the WiFi interface used to control the ‘bot from a smartphone. This is achieved using an app from JJRobots, an open-source robotics teaching resource. Stepper motors are controlled by DRV8825 modules sourced from amazon, and an MPU6050 gyro rounds out the major components. Naturally, source code is available on GitHub for your reading pleasure.

It’s remarkable that in this day and age, it’s possible to build such a project with little to no soldering required at all. With a credit card and a healthy supply of patch leads, it’s possible to whip up complex digital projects quite quickly. We’ve seen a similar approach before, too. Video after the break.

[Thanks to Baldpower for the tip!]
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3000W Unicycle’s Only Limitation Is “Personal Courage”

Electric vehicles are fertile ground for innovation because the availability of suitable motors, controllers, and power sources makes experimentation accessible even to hobbyists. Even so, [John Dingley] has been working on such vehicles since about 2009, and his latest self-balancing electric unicycle really raises the bar by multiple notches. It sports a monstrous 3000 Watt brushless hub motor intended for an electric motorcycle, and [John] was able to add numerous touches such as voice feedback and 1950’s styling using surplus aircraft and motorcycle parts. To steer, the frame changes shape slightly with help of the handlebars to allow the driver’s center of gravity to shift towards one or the other outer rims of the wheel. In a test drive at a deserted beach, [John] tells us that the bike never went above 20% power; the device’s limitations are entirely by personal courage. Watch the video of the test, embedded below.

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A Robot That Can Still Keep Its Balance After A Night In The Pub

One of the star attractions at the recent bring-a-hack prior to our London unconference was [Dan]’s two-wheeled self-balancing robot. As the assorted masses of the Hackaday readership consumed much fine ale and oohed and ahhed over each others work, there it stood on a pub table, defying all attempts to topple it.

In a way a successful self-balancer can look surprisingly unexciting because it achieves the seemingly unimpressive task of just standing there and not doing much except trundling about, but to take such a superficial view belies the significant feat of engineering that gives the self-balancer its party trick. And it’s no mean achievement to create one from fairly basic hardware, so how has he done it?

The 3D-printed frame holds a pair of stepper motors to do the hard work, while a piece of stripboard acts as carrier for boards containing the MPU6050 accelerometer and DRV8825 stepper motor drivers. Meanwhile the brains of the whole show started as an Espruino Pico but has since been moved to an ESP32.

There is a linked GitHub repository with all the code, and if our description of seeing it in a London pub isn’t good enough for you then you can see it in action in the video below.

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Balancing Robot Needs Innovative Controller and Motor

A self-balancing robot is a great way to get introduced to control theory and robotics in general. The ability for a robot to sense its position and its current set of circumstances and then to make a proportional response to accomplish its goal is key to all robotics. While hobby robots might use cheap servos or brushed motors, for any more advanced balancing robot you might want to reach for a brushless DC motor and a new fully open-source controller.

The main problem with brushless DC motors is that they don’t perform very well at low velocities. To combat this downside, there are a large number of specialized controllers on the market that can help mitigate their behavior. Until now, all of these controllers have been locked down and proprietary. SmoothControl is looking to create a fully open source design for these motors, and they look like they have a pretty good start. The controller is designed to run on the ubiquitous ATmega32U4 with an open source 3-phase driver board. They are currently using these boards with two specific motors but plan to also support more motors as the project grows.

We’ve seen projects before that detail why brushless motors are difficult to deal with, so an open source driver for brushless DC motors that does the work for us seems appealing. There are lots of applications for brushless DC motors outside of robots where a controller like this could be useful as well, such as driving an airplane’s propeller.

[Nick Thatcher]’s Plan-B Is A Commuter Electric Unicycle

[Nick Thatcher] is a serial builder of self-balancing rides. His various Segway clones and unicycles have until now suffered from one significant problem, that of portability when not being ridden. Taking one on a train was a significant undertaking, hardly convenient in a personal transport machine.

His latest design, the Plan-B, is an electric unicycle designed to address this problem to create a truly portable piece of commuter transport. It has been designed to be as compact as possible with the ability to fold to fit in a confined space, and the weight has been reduced to a minimum.

Power comes from a 24V 350W geared motor kept on a leash through a Dimension Engineering motor controller by an Arduino with a gyro to maintain the unit’s stability The battery is an ULTRAMAX LiFePO4 , and the single wheel is an inexpensive plastic wheelbarrow part with chain drive from the motor.

The result is both rideable and portable, though with a 10mph top speed not the fastest of personal transport. He’s posted a video which you can see below the break, showing him taking it on a train journey and traversing the British urban landscape.

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3D Printed Electric Unicycle

Actually riding around at 30 km/h on a 3D printed means of transportation is pretty gnarly, if not foolhardy. So we were actually pleased when we dug deeper and discovered that [E-Mat]’s unicycle build is actually just a very nice cover and battery holder.

We say “just”, but a 3D-printed design takes a couple of cheap parts (the wheel and pedals) from the Far East and turns them into a very finished-looking finished product. Custom bits like this fulfill the 3D printing dream — nobody’s making it, so you make it yourself. And make it look pro.

It turns out that other people have noticed this motor/controller/pedal combo as well. Here’s some documentation to get you started.

It’s funny. Just four years ago, self-balancing powered unicycles were the realm of the insane hacker. Then came some hacker improvements, and now we’re at the point where you can mail-order all the parts and 3D print yourself a fancy enclosure.

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Reverse Engineering Hoverboard Motor Drive

The must-have toy of the moment last winter was the “Hoverboard”. We all probably secretly wished them to be the boards from the Back to the Future series of films made real, but the more achievable reality is a self-balancing scooter somewhat akin to a miniature Segway. It seemed every child wanted one, schools banned them, and there was a media frenzy over some of the cheaper models that lacked protection circuitry for their li-ion batteries and thus had a tendency for self-incineration.

[Drew Dibble] is interested in the Power Racing Series (PRS), in which toy electric cars are souped up for competition. Casting around for a source of cheap and relatively powerful motors he lit upon the self-balancing scooters, and waited on Craigslist for the inevitable cast-offs. His resulting purchase had two 350W brushless hub motors and all the associated circuit boards for motor control, gyroscope, and oddly a Bluetooth speaker. The motor control board received an unknown two-wire digital feed from the scooter’s control board, so he set to work investigating its protocol. His write-up of how he did it is an interesting primer in logic line detective work.

Hooking up his logic analyzer he was quickly able to rule out the possibility of the control signal being PWM because all signals followed the same timing. Both lines had data so he was able to rule out I2C, for in that case one line would carry a clock. He was therefore left with a serial line, and taking the 38 microsecond timing interval, he was able to calculate that it had a rather unusual bitrate of 26315 BPS. Each packet had a multiple of 9 bits so he either had 9-bit or 8-bit with parity, and trying all possible parity schemes resulted in parity errors. Therefore the boards used a highly unusual 9-bit non-standard bitrate serial port. Some experimentation led him to an Arduino library, and he was able to get some movement from his motors. Some clever timing detective work later and he could make them move at will, success!

All his code for the project is on GitHub, for his 9-bit SoftwareSerial library and a motor control sketch.

If you want a real Back to the Future hoverboard then you may have to wait a while longer. We have featured a replica made as an unrideable floating artwork though, and a working board that is more of a personal hovercraft.

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