Self-balancing Arduino Does It Without An IMU

September 26, 2013 by Mike Szczys 15 Comments

The miniscule size of this self-balancing robot makes it a cool project. It actually uses the motor and wheels from a small toy car. But when you look into how the balancing act is performed it gets way more interesting. The larger versions of this trick pretty much all use Inertial Measurement Units (IMUs) which are usually made up of an accelerometer and a gyroscopic sensor. This has neither.

The black PCB seen to the right of the robot is an IR reflectance sensor. It shines an IR led at the floor and picks up what reflects back. [Sean] added this hack because the gyro sensor he ordered hasn’t arrived yet. The board has a trimpot which is used to adjust the sensitivity. You have to tweak it until it stands on its own. See for yourself after the break.

Self balancing robot builds are a great way to teach yourself about Proportional-Integral-Derivate (PID) algorithms used in a lot of these projects.

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Salvaging Parts From Broken Roomba Robots

July 8, 2013 by Mike Szczys 11 Comments

salvaging-parts-from-broken-roombas

The great thing about hacking on Roombas is that iRobot used quality parts to build them. [Jason] got his hands on a broken 5XX series Roomba and posted an article about how he reused the salvaged parts.

What you see above is one of the results of his work. This little bot takes commands from an IR television remote control. But he also used the setup to make a self-balancing bot. The two motors from the Roomba have magnetic rotary encoders with 8-bit resolution. Pair this with a well-tuned PID algorithm and you’re in business. The video below shows him testing a motor with his PID code.

You don’t get very much info on the guts of the donor robot. If that’s what you’re looking for you need to look at [Dino’s] Roomba 4000 teardown.

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Kalman Filter Keeps Your Bot Balanced

September 10, 2012 by Mike Szczys 19 Comments

If you’re looking to improve the stability of your self balancing robot you might use a ~~simple~~ horrifying equation like this one. It’s part of the journey [Lauszus] took when developing a sensor filtering algorithm for his balancing robot. He’s not breaking ground on new mathematical ideas, but trying to make it a bit easier for the next guy to use a Kalman filter. It’s one method of suppressing noise and averaging data from the sensors commonly used in robotic applications.

His robot uses a gyroscope and accelerometer to keep itself upright on just two wheels. The combination of these sensors presents an interesting problem in that accelerometer input is most accurate when sampled over longer periods, and a gyroscope is the opposite. This filter takes those quirks into account, while also factoring out sensor noise. Despite the daunting diagram above, [Lauszus] did a pretty go job of breaking down the larger function and showing us where to get the data and how to use it in microcontroller code.

Self Balancing Robot With Wii Parts

January 5, 2012 by Kevin Dady 8 Comments

[Moser] is looking to build a quadrocopter sometime in the future, without plunking down a good chunk of change for a kit model. Looking for a good place to start he figured why not work on the control system. Thinking that the balance of the flying platform of doom would be similar to working out a self balancing robot he spent a couple days and made his self balancing robot.

Armed with a plan, and a logic analyzer, he went out and got a Wii Motion Plus, which is an inexpensive three axis gyroscope, and a nunchuck which features an accelerometer which both can be found in just about any strip mall. After fiddling for a day getting the Wii nunchuck and motion plus to play nice all it took was a little more time to code up the self balancing routines.

And while its not perfect, all its going to take is a little tweaking and maybe some faster servo motors to get things up to top notch.

Join us after the break for a couple quick videos.

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