http://www.instructables.com/id/SciChair-Balancing-Electric-Chair/

Food      Living       Outside        Play        Technology       Workshop

SciChair (Balancing Electric Chair)by ScitechWA on July 27, 2011

Table of Contents

SciChair (Balancing Electric Chair) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Intro:   SciChair (Balancing Electric Chair) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Step 1:   Details about the build . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Step 2:   Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Step 3:   Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Step 4:   The frame . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Step 5:   Motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Step 6:   Electronics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Step 7:   The Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Related Instructables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

http://www.instructables.com/id/SciChair-Balancing-Electric-Chair/

Intro:  SciChair (Balancing Electric Chair)One day at work we decided we would build something cool.So there was only one place to look to get some ideas. Instructables!

We had a criteria of that it had to be driven by an Arduino!Searching through the vast amounts of really cool projects we found XenonJohn's Balancing Electric Skateboard   http://www.instructables.com/id/Easy-build-self-balancing-skateboardrobotsegway-/

We thought we should build a stand on Balancing scooter. And so we did but that's another instructable for another day.

But we needed something original. What about a Balancing chair my boss said. Now that's cool!

We happened to have a Carbon Fibre Racing chair just sitting around not being used so we started with that.Because of the cool look of course!

We previously ordered a couple of geared down 250W scooter motors and some wheels to suit.Now to order the electronics!

Now reinventing the wheel is a waste of time.XenonJohn has already spent the time developing the code and the hardware to use.

So we ordered exactly what he recommended.

Now power! We use Makita drill batteries for most of our travelling exhibits as they are easy to get, to charge and we have a few batteries laying around for just such apurpose.

Here is a short video of the chair being driven around. Note the 3rd build Balancing scooter too doing a drive through.

http://www.instructables.com/id/SciChair-Balancing-Electric-Chair/

http://www.instructables.com/id/SciChair-Balancing-Electric-Chair/

Step 1: Details about the buildOk I'm going to go through this build a little bit in reverse as we built the chair fairly quickly and forgot to take build photos.

I'm not going to go into detail about the balancing software or how it works as XenonJohn has already described this so well.I will give you details on how we built ours and what you will need to do to build your own.

The electronics is exactly what XenonJohn used on his skateboard and the code is the same too!I will describe the slight tweeks we have done and there is a complete new code coming at a later date to drive it completely with a joystick.

Step 2: PartsOk your going to need some parts.eBay can be your friend here. Parts Needed:

Chair - Any type will do. Something comfortable that you can lay back into.Arduino UNO - Check your local suppliers or eBay.Sabertooth 2x52 Motor Controller- www.dimensionengineering.com or a local supplier.5 DOF accelometer - http://www.sparkfun.com/products/9268 http://littlebirdelectronics.com2 scooter motors - I would recommend 200w and up. www.oatleyelectronics.com or eBay. Have a look around your area.Batteries - SLA batteries are good and cheap, Power drills can be quite inexpensive too.Wheels - Larger wheels are better for bumps. Get one with the same sprocket chain type as the motors if possible.We got our wheels from www.oatleyelectronics.comShielded multi core cable for the accelometer and heavy power cable for the motorsDeadman switchToggle switch for turning. A joystick is good for this.Toggle switch for adjusting balance poisition.DC connector for Arduino.10k resistorsDIL pins to suit ArduinoDouble sides tapeScrews etc 

 

http://www.instructables.com/id/SciChair-Balancing-Electric-Chair/

Step 3: ToolsYour going to need some tools.Other than the normal bits you will need somebody with a welder and can weld to make the frame.

Some other tools you will need:

Drill and drill bitsSoldering iron and solderWire cutter and wire strippersHeat shrink and hot air gun to shrink it

Step 4: The frameHere are the picture for the design of the frame.As you can see it's quite basic.

A U shape over each wheel to bolt the wheel to and to hold the motors.A bar between these as the main member.We first off didn't have the gusets in there (Triangle shape next to the wheel)The bottom bar started bending, so make sure that the main member is heavy duty and have reinforcing to the wheel U shape.

We added a centre tube for the two removable skids.I do recommend adding skids. They stop a lot of breakages and accidentsWe made the seat mounts adjustable for a balance point. Not needed.Just mount your seat in the middle.

We used a Carbon Fibre Racing Chair we just had sitting around, but most people don't have them gathering dust in the corner.So a school seat, car seat or what ever you can find that's comfortable and probably has a long back with head rest if possible.

http://www.instructables.com/id/SciChair-Balancing-Electric-Chair/

http://www.instructables.com/id/SciChair-Balancing-Electric-Chair/

http://www.instructables.com/id/SciChair-Balancing-Electric-Chair/

Step 5: MotorsThe motors we used are geared 250W 24V brushed motors from www.oatleyelectronics.comMotor RPM is about 320 RPM.

The wheels were purchased from the same place.The fine tooth gear was removed from the wheel and a BMX gear was fitted on the thread.The pitch of the BMX gear was the same as the motor 12.7mm.

All though this works ok, you do get a bit of chain stretch and the keyway on the motor gear will wear out evenually.It is better to use toothed belts here if possible. The cost does go up when using these!

A plate was made to hold the motors and it bolts to a piece of metal welded to the frame.The piece of metal has two slots cut into it to allow the motor to slide up/down to take up the chain slack.There are different ways of doing this. Something like how a car altinator mounts might be another way.Open the bonnet of your car and see how it's done.

 

http://www.instructables.com/id/SciChair-Balancing-Electric-Chair/

http://www.instructables.com/id/SciChair-Balancing-Electric-Chair/

Step 6: ElectronicsThe electronics is basically three things.The motor controller 2x25 Sabertooth http://www.dimensionengineering.com/sabertooth2x25.htmThe arduino Uno and the accelerometer.

Mount the motor controller and ardunio somewhere where they won't get damaged when you crash!Yes you will crash!!!!!!!!!

The Acceleromoter needs to be mounted preferably axle height and vertical.We used double sided tape as it's a good insulator and sticky!!!!!!!Make sure it's in a nice waterproof area and maybe even heat shrink it water tight.A glue coated heatshrink is good for this.

We used shield cable for the wiring as it will stop any added noise getting into the system.

Make sure it is held on tight. If not you will have a bucking bull chair! Believe me I know about this!

The unit has a few switches to add.

The dead man switch. The big red button that has to be held at all times to make the unit work.1.Main Power. Cuts power to everything. Ours was built into the battery holder.2.Joystick. Allows you to turn left/right and drive forward in up coming code.3.Tilt Adjustment. Allows you to adjust your balance point4.

Find a good safe, easy to use spot to mount these.Connect all units together and wire these up as per the wiring diagram.The wiring is the same as Xenonjohn's Skate board.

See here as he has a detailed instruction on this.http://www.instructables.com/id/Easy-build-self-balancing-skateboardrobotsegway-/step19/Electronics/

I have added 2 extra wires and resistors for a later code change to be able to drive it forward with the joystick.

 

http://www.instructables.com/id/SciChair-Balancing-Electric-Chair/

http://www.instructables.com/id/SciChair-Balancing-Electric-Chair/

http://www.instructables.com/id/SciChair-Balancing-Electric-Chair/

Step 7: The CodeThe main code I use is XenonJohns code off his skate board. I used the rocker steering!

Start herehttp://www.instructables.com/id/Easy-build-self-balancing-skateboardrobotsegway-/step42/IMU-testing-sketch/Go through the process as he says to test your unit.

There will be new code soon that has a few extra features.One of these will be proportional steering and forward/back movement.

Coming Soon!

Related Instructables

Easy build selfbalancingelectricskateboard byXenonJohn Seg...stick. by

scolton

Self balancingone wheeledelectricskateboard byXenonJohn

Anglemeasurementusing gyro,accelerometerand Arduino byotaviousp

Fun Electric 3Wheel ScooterSegwayknockoff under$100 (video) byprabbit22m

TransitionElectricScooter. by saul

Comments

2 comments Add Comment

 kelseymh says:  Aug 11, 2011. 9:39 PM  REPLYA technical comment. This is an awesome chair. If a real wheelchair user wanted to use it, they would have to have some way to support their legs. Youmight think about how you could add a lightweight frame (some bent tubing and footpads) while still maintaining the balance and stability, for version 2.

 kelseymh says:  Aug 11, 2011. 9:37 PM  REPLYThis is so close to being a Featured I'ble!

You need to add pictures to the three steps which don't have them. Please, please, add a set of photos of the components to Step 2 (your own photos for thebig stuff, steal some obvious clip art for the little things (resistors, tape, blah blah blah) and of the tools you used to Step 3. On the final step, you could add apicture of the chair in action.