Do-it-yourself self-balancing...things...have been around almost as long as commercial self-balancing things. Obviously the homemade versions are not as smooth, reliable, or failsafe as the real thing, but they are still pretty captivating. And they make great mechanical/electrical builds with some interesting control theory mixed in. In the final step, I provide a few references to good DIY self-balancing...whatever...builds.

In 2007, I helped with this other self-balancing scooter build at the MIT Edgerton Center, and since then we've gotten many interesting questions by email about how it works. Baseline self-balancing functionality is actually surprisingly simple, and maybe the purpose of this Instructable is to take this simplicity to the extreme. To that end, I present: Seg...stick.

Segstick is a self-balancing...well, literally some kind of broomstick I found in the MITERS workshop. It is powered directly by two DeWalt cordless drills chucked to two 6" wheels. The controller is an Arduino. Additional supporting devices include an Inertial Measurement Unit (IMU) from Sparkfun and two motor drivers from Pololu.

Is it the best DIY self-balancing vehicle ever? No, not even close. But it only took about two days to build, and it is stripped down to the bare necessities. Thus, I hope to point out the modules and concepts involved in making any self-balancing vehicle rather than the specifics of this one. To start with, some physics...

Step 1: Physics says it's easier to build a full-size self-balancing thing.

One question we get a lot is: Can this work on some kind of miniature self-balancing robot? Yes, but, the laws of physics make it harder to control a small inverted pendulum bot than a full-sized rideable self-balancing vehicle. 

For one, the mechanical time constant of a small self-balancing robot is faster. Imagine the difference between trying to balance a broomstick on your finger and trying to balance a pencil on your finger. The controller for a small robot has to be that much faster to keep up with the physical system.

Additionally, a human rider takes some of the burden off the electronic controller, since the human mind is a pretty good controller too. For example, the accelerometers used on self-balancing platforms can't distinguish between standing still and moving at a constant velocity, but a human rider can. The human rider can adjust by leaning forwards or backwards to speed up or slow down.

So, this Instructable focuses on a full-size vehicle, albeit a relatively small one. In the final step, there are some links to balancing robots.
<p>great and thanx for share...</p>
<p>Nice one...</p>
<p>Awesome work</p>
<p>Great One</p>
Great project
<p>Awesome job.</p>
<p>Wow...Its really awesome</p>
<p>Qu&eacute; buena idea! Cool!!</p>
<p>I'd love one of these around our campus.</p>
<p>Great idea</p>
<p>lovely, creative</p>
amazing.i am going follow your instructions to make one.but i know nothing about programing and electrions.so dont think my questions are simple and stupid.i really dont know.<br>1.Can i use different motor driver?<br>2.Can alter the structures of the car(eg distance between two wheels,size of standing board....)<br>if these changes will effect the program to run smoothly?<br>thanks
answer, please! what is the function of steering pot? How it affects on the controlling of ballancing robot?
The steering pot applies a differential command to the motors, after all the balancing calculations. It adds some amount to one motor and subtracts some amount from the other motor, which causes the platform to turn. The amount it adds and subtracts is set by the steering gain, KS.
<p>You can make it if you follow the instructions</p>
<p>Yeah, can we make it together?</p>
<p>This Segstick really very good?</p><p>I want it too...))</p>
<p>Just a note to let you know I have added this to the collection: Cordless Drills Hacking for Other Uses !</p><p>&gt;&gt; <a href="http://www.instructables.com/id/Cordless-Drills-Hacking-for-Other-Uses/" rel="nofollow">http://www.instructables.com/id/Cordless-Drills-Hacking-for-Other-Uses/</a></p><p>Take a look at a bunch of project involving odd uses of drills.</p><p>and for even more drill info</p><p>&gt;&gt; <a href="http://www.instructables.com/id/Cordless-Drills-A-Collection-of-Collections/" rel="nofollow">http://www.instructables.com/id/Cordless-Drills-A-Collection-of-Collections/</a></p>
<p>Regarding Step 10,</p><p>I've seen accelerometers with specs that say 'capable of measuring accelerations with output data rates from 1 Hz to 10 kHz'.</p><p>If the motion will be under 10khz, do you think a gyro is still needed? Or will the readings be so noisy that even when operating under 10khz, the accelerometer data will still need to be filtered with gyro data?</p>

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