Yet Another Self-Balancing Unicycle

unicycleScitech

No one has time to hone their balancing skills these days, and if building your own Segway doesn’t generate enough head-turning for you, then the self-balancing unicycle from the guys at [Scitech] should. Their build is chain-driven, using easy-to-find salvaged Razor scooter parts. Throw in a motor controller, 5DOF IMU and some batteries and it’s almost ready to burn up the sidewalks in hipster-tech style.

Some of the previous unicycle builds we’ve seen are a little on the bulky side, but the [Scitech] cycle aims for simplicity with its square tube steel framing and footrests. As always, unicycle builds like these take some effort on behalf of the rider: shifting your weight controls steering and throttle. The [Scitech] gang also discovered that it’s usually best when you don’t accidentally wire the motors up to the controller backwards. We recommend that you find a helmet and watch the video after the break.

Too-cool-for-unicycle hackers can build a dangerously fast e-skateboard instead.

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IMU boards as next-gen motion capture suit?

imu-boards-motion-capture-suit

This guy takes a drink and so does the virtual wooden mannequin. Well, its arm takes a drink because that’s all the researchers implemented during this summer project. But the demo really makes us think that suits full of IMU boards are the next generation of motion capture. Not because this is the first time we’ve seen it (the idea has been floating around for a couple of years) but because the sensor chips have gained incredible precision while dropping to bargain basement prices. We can pretty much thank the smartphone industry for that, right?

Check out the test subject’s wrist. That’s an elastic bandage which holds the board in place. There’s another one on this upper arm that is obscured by his shirt sleeve. The two of these are enough to provide accurate position feedback in order to make the virtual model move. In this case the sensor data is streamed to a computer over Bluetooth where a Processing script maps it to the virtual model. But we’ve seen similar 9-axis sensors in projects like this BeagleBone sensor cape. It makes us think it would be easy to have an embedded system like that on the back of a suit which collects data from sensor boards all over the test subject’s body.

Oh who are we kidding? [James Cameron's] probably already been using this for years.

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Prosthetic spines become musical instruments

spine

[Joseph] and [Ian] have been working on a project that turns physical objects into bendable, snake-like controllers

This build is the culmination of an earlier project that digitally modeled a flexible object with accelerometers, gyroscopes, and IMUs. When we first saw this build, we wondered what it could actually be used for, but it seems [Joseph] and [Ian] came up with a pretty cool use for it: turning prosthetic spines and ribs into musical instruments.

These flexible devices are loaded up with sensors along their joints and are connected to a microcontroller with a Zigbee radio transceiver. The positioning data from these devices is transmitted to a computer where it’s turned into audio, effectively turning a dancer into a musical instrument.

For an art piece, it’s pretty cool, but as a new means of interacting with a computer, we’re thinking this might be a game changer. Imagine a gauntlet loaded up with IMUs being turned into a waldo, or precisely controlling virtual objects naturally with your hand.

Clean and minimal self-balancing robot

vertibot-self-balancer

The VertiBOT is a self balancing robot project taken on for the purpose of exploring how the sensors work in conjunction with some PID algorithms.

[Miguel] didn’t roll any extras into the build. But you have to admit that makes it look interesting. There’s almost nothing to it and yet, as you can see in the clip after the break, he accomplished everything he set out to.

The body and wheels are 3D printed, with black bands for tires to help give it some traction. Note the connection in the center of the body which allowed him to make a longer part by printing in two stages. On the electronic side of things he’s using an Arduino Nano. A level converter lets it communicate with the 6 DOF IMU board which is used to detect movement. Three potentiometers provide a way for him to tweak the PID loop without having to bother with reflashing any code. And of course there’s an option to control it remotely thanks to a Bluetooth module also in the mix.

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Self-balancing unicycle using Arduino and Sparkfun IMU

Raptor-Bike-self-balancing-unicycle

Here’s proof that you can build cool stuff with simple tools. This self-balancing unicycle uses an Arduino and a five degree of freedom IMU from Sparkfun to keep the rider upright. Well, it’ll keep you upright as long as you have good side-to-side balance. But that’s true of any unicycle, right?

The Raptor was built by [Nick Thatcker] who is no stranger to self-balancing transportation. A few years back he built a Segway clone and the same type of geared motor used in that project also went into this one. I connects to the wheel with a chain, allowing him to keep the motor hidden in the saddle. He gets between 90 and 120 minutes of used on one charge with a top speed of 10 MPH. The motor could move you along faster but he has limited this in firmware to ensure it has enough power to ‘catch up’ if you lean too far forward.

Don’t miss the demo after the break. If you like this unicycle there are several others worth looking at.

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Wii Nunchuck controlled robot exhibits rock solid balancing

[Willy Wampa] is showing off his self-balancing robot. What strikes us about the build is how well tuned his feedback loop seems to be. In the video after the break you will see that there is absolutely no visible oscillation used to keep its balance.

The parts used are quite easy to obtain. The acrylic mounting plates are his wife’s design and were custom cut through the Pololu service. They were also the source of the gear motors. He’s using a SparkFun IMU with an Arduino and a motor shield. He first posted about the build about a month ago, but the new revision switches to a Pololu motor driver shield which he says works much better, and adds control via a wireless Wii Nunchuck.

The PID loop which gives it that remarkably solid upright stance is from a library written by [Brett Beauregard]. Once again the concept of open source lets us build great things by standing on the shoulders of others.

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Tutorial explains the concepts behind an IMU

[Anilm3] wrote in to share the IMU tutorial series he is working on. An Inertial Measurement Unit is most often found in self-balancing robots and quadcopters, providing enough high-speed sensor data to keep up with the effects of gravity.  He previously used some all-in-one IMU devices in school which did most of the work for him. But he wanted to grind down and look at what each sensor spits out and how those measurements are used. The first installment deals with the accelerometer, using its data to calculate pitch and roll. For these demonstrations [Anilm3] is using this ADXL345 sensor board, an Arduino, and some processing sketches for testing.

Whenever working with sensors you need to take noise into consideration. The post shows how to implement a low-pass filter in the code which will help smooth out the readings. The filtered data is then fed to a couple of mostly-painless formulas which calculate the movement of the accelerometer in degrees. The demonstration sketch is mapped to a 3D cube to give you an idea of how accurate the accelerometer is. There’s a little bit of lag which would let a self-balancing robot have a nasty fall. The solution to this issue will be discussed in upcoming parts of the series. The next installment tackles the gyroscope sensor.

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