Balancing Robot

This is a very simple robot that uses a simple switch as a sensor and stands on only two wheels with inverted pendulum mechanism.
When the robot is going to fall the motor starts and moves the robot to the direction it is going to fall, so the motor torque about the center of gravity that is higher than the motor makes the robot balanced.

Step 1 Things you need

To make this robot you need following parts and tools:
small electric motor
some gears
(or a motor with gearbox)
a shaft
two wheels
some sheets of plastic to make bearings and the robot neck
two battery holders
4 AA batteries
one button cell
one SPDT (single pole double throw) switch with a metal lever
one toggle switch for the on/off switchs
one nail
some wire
soldering iron
some glue

Comments

[David97]

I built one of these and my one doesn't tip over. It is about 11 cm in height. Also mounting the switch out further from the axel helps it is 1.5 cm from axel from the cloest edge on switch. Hope this helps to get your one working well.
Aso it is a good idea to have the hight of switch adjustable. As I spent 2 hours adjusting the hight.

[vahid_you2004]

Good idea, by an adjustable switch you can make robot standing on a steep too.
Could you upload a video of your robot, it would be very helpful for ones who want to make one.

[AlKaswa]

where would i find a single pole double throw switch

[vahid_you2004]

Electronic devices shop

[milsorgen]

 aka radioshack

ive also pulled one out of a computer, and several other interesting looking switches. mostly out of the optical drives, front panels and a somewhat of floppy drives, but if you keep your eyes open...

[ben_xman]

I've also noticed that radioshack has accelerometers. I wonder if you could use those too? Might be more arduino based than BEAM though....

[Chowmix12]

try the buttons from mouses. they are conveniently SPDT, (not needed) but they have no lever, i've been able to fashion ones from paperclips and other simple materials.

[TigrisLi]

Where did you get the wheel with the shaft??

[vahid_you2004]

A toy!

[TigrisLi]

ok, thanks!

[ladieslilman98]

Add a second sensor, the motor wont work as hard, and it will stay balanced longer.

[tobyscool]

i made the hugest mistake i shorted the batteries EPIC FAIL so my battery bursted

[Exocetid]

This robot is great and I really like how you did the position sensor, extremely clever and what "Instructables" is all about. That said, you might want to change the switch on your sensor, which basically just gives you "Bang-Bang" control and hence the instability, to a potentiometer or variable resistor. That may involve putting an amplifier in there, but we EE's have been allowing ME's to use electronics for quite some time now ;-) (mechatronics)

[vahid_you2004]

Good idea. I like mechatronics a lot.

[ForgetMyProfile]

It seems to me that the center of gravity is high which causes the robot to have to react faster than it is capable of due to the circuitry delays, inefficiency of the wheels to move as quickly as needed.

I have two Segways (a blast, by the way) and they stand up on their own. It's fun to watch them "dance"..

I literally had to go to the factory in NH to take a class on how to ride these models. Yes, long time ago.

What they suggested this: to stabilize my units when first riding it, add some weights to the saddle bags on either side. It not only helped me when learning, it helped the Segway stay upright without excess movement

So what I'll seggest (lol) to you is this: get the center of gravity lower by moving the batteries down or adding weight to the bottom of the plastic. That should allow the bot to stay upright without falling over.

LET ME KNOW HOW THAT WORKS.

Robb
Grand Rapids, MI

[iMakeItHappen]

 Thats really cool and a good idea, and i have an alarm clock like that, it has a very dense material on the bottom with a rounded edge, so to turn it off u just push it back, then it pops back up.

but why do u have 2 segways, its pretty cool, i just dont understand y u have them.

[ForgetMyProfile]

Originally, I bought the two Segways for advertising purposes.

My intention was to hire good looking college gals to ride them around with our company logo on the side of the saddle bags, answering questions about our business and handing out literature.

Great marketing idea, but have not had enough time to devote to the project.

[Robot Lover]

  I like this. Reminds me of my youth, building a line following robot with a car battery and two window regulator motors from an old Lincoln.
  It would be interesting to try it with tilt switchs (**MERCURY is BAD kids**) and perhaps make two stages of power, voltage divider between cells for those times when it tilts beyond a certain range the additional voltage is switched on.
  Also would be neat to try a magnetic pendulem with reed switchs.

Good Job.

[Chowmix12]

but you would need a spdt tilt switch... i think this switch is better because of its immediate response and its adjustable. You can't adjust the force of gravity on the tilt sensor...

[stephenniall]

Mercury is Cool !

[l33tm4s73r]

lolz

[Robot Lover]

it's true.

[ratgod]

Thats pretty good considering their is no microcontroller doing the balancing, its a neat simplistic design.

excellent instructable.

[lothartje]

nice music :)

[godscountry]

this is interesting,another way to balance on one or two wheels without the high cost,if perfected,it might make for some fun toys.

[cupnoodles2]

its pretty nice i made one myself but its not working that great lol
i think its because i only used two gears one on the motor and another one on the driver shaft so there's no mechanical income but im not sure if its that or it is just that the batterries are not fresh enought :O

thanks for the instructable and i apologize for my bad english

[cupnoodles2]

honestly i know that there's not enought torq lol since i didnt used a third gear well im remaking it xD

[dingo27]

This is awesome! So simple, but i wouldnt reccomend soldering a battery, it may explode 

[Mikishiwa]

will it be possible to make this robot drive straight without balancing in one spot continuously? For example using this www.instructables.com/id/Tilt_Sensor_cheap_easy_nontoxic/ as a switch, so it will be able to balance in two directions an maybe drive 2-5 metres without falling.

[vahid_you2004]

To move this robot you need more complicated controlling system than a simple switch, you must also have some motor sensors and a microcontroller to measure motor speed and control its torque and speed.
For more info search "balancing robot" on internet.

[chengtianzheng]

Here, the best design!

[chengtianzheng]

nice working,thank you!

[ewiemers]

The problem isn't the center of gravity, it's stability. The switch will work as a measurement device so long as the robot is VERY close to vertical. If you get much past that narrow threshold, the robot doesn't add more torque to the motor to compensate. If you want it to be more stable, you'll have to use some analog device to measure the tilt-angle and another circuit to control motor torque through input voltage. A simple sensor would be a multi-turn potentiometer.

[vahid_you2004]

You're right.

High CG object has high moment of inertia, so it needs more moment to move and has more stabillity. Because of these you must choose the longest robot and consider your motor power.

The more complex controlling system, the more stabillity. but the most important feature of this robot is that it is simple (according to the the others comments)

[Binary Ninja]

For a future robot you may want to put the weight lower so it has a lower center of gravity.

[rimar2000]

No, the center of gravity must be higher. You played to hold a stick upright in the palm of your hand? The longer, is easier to keep it vertical.

[TwistedmindZ]

well the higher the weight is the more torque it creates for the motor to overcome to stay balanced. When you are holding a stick upright torque isn't a problem relative to your size. So i too think lower center of gravity would make it more stable.

[vahid_you2004]

Making the neck longer or putting the weight higher both of them raises the CG. Balancing a high CG object is easier than a low CG object but It need more power to balance a high CG object than a low CG object because a high CG object has more moment of inertia.

[rimar2000]

I don't agree with you. Sorry I can not do the test, but I am sure.

[rimar2000]

Well, but, have you tried?