How To Build a Self Balancing 2 Wheeled Scooter Inspired by the Segway
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Day 1 2nd October 2012
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Above is a short video of the scooter in action.
As always the idea of building something has to conform with a few basic rules which are to make it out of scrap & every day items that are easily found so anyone can build it & I would like to limit the whole project to $500 NZD.
OK, after a lot of googling around & checking specs & other peoples successes & failures I have enough information to give this project a go.
If you are following the daily progress of this project and making your own scooter then please read all 10 pages before starting. Because I have documented not just the successes but also the failures it means that what may have been a good idea early on in the project may have been removed later because it didn't work as well as expected. At least this way you can learn from my mistakes.
Here are the main points (as far as I know):
1/ Choosing & sourcing the motors
2/ Choosing & sourcing the wheels & gearing
3/ Choosing & sourcing an accelerometer (this helps with calculating the angle so the scooter can be controlled)
4/ Choosing & sourcing a gyro (the angle is needed so the scooter can be controlled)
5/ Choosing & sourcing a micro controller (this is what the gyro & accelerometer talk to)
6/ Choosing & sourcing a motor controller (this is what the micro controller talks to, so it can change the motor direction & speed)
7/ Wire all the bits up
8/ Program the micro controller
9/ Test what happens & make sure it all works before proceeding further
10/ Building a frame to support rider & wheel assembly
11/ Build a flat footplate to fit over frame
12/ Mount steering handle
13/ Mount batteries so the centre of gravity provides best performance
14/ Mount electronics & wiring
15/ More testing
16/ Build a steering mechanism for handle
17/ Test steering
18/ Maybe add lights & brake lights, reflectors etc
19/ Give it all a good coat of paint
This is day one & the first step in making a homemade DIY self balancing 2 wheeled scooter inspired by the Segway.
I can already see that even naming this project is going to be difficult, so I'm going to call this thing a scooter from now on until I can come up with something better.
I will be documenting & publishing each step, I am not able to work on this every day but I hope to get 3 days a week available for this project.
The Motors
There are many DC motors & many ways of connecting them to the wheels but as far as I can see wheelchair motors are perfect. They are designed for high torque & low revs but the best part is that they are already connected to the wheels, they have their own gearbox & the whole assembly is designed to be mounted easily. Why make a design difficult when you can bypass potential problems & use these motors.
Well there is one drawback, they can be expensive, if you look on Ebay then you will find many at between $50-$200 USD, $150 USD for a matched pair is fairly common. But if like me you need them shipped to another country then the shipping will cost a further $200.
I managed to pick up an almost complete wheelchair for $200 NZD in New Zealand but it took a lot of time & effort to find one. The chair is an Invacare PT2000 power chair.
As this project progresses we will find out if these motors are powerful enough to keep an adult balanced. The spec on each motor is 24v, 8A, & 120 RPM. This equates to almost 200 watts for each motor so lets hope it's enough.
Update March 2013. We've managed to source some motors & other electronics at a great price & have started to make up kits so you can make your own, check out the bottom of the Day 10 page.
Here's a video of how to check the motors, I added the video as it seemed that a lot of people had purchased wheelchair motors for different projects but found that each motor had 4 wires & they were not sure what to do with each wire. When I connect power to the electrical brake you can here it disengage with a click in the video, actually the wiring was loose so you can here it click a few times.
OK, after a lot of googling around & checking specs & other peoples successes & failures I have enough information to give this project a go.
If you are following the daily progress of this project and making your own scooter then please read all 10 pages before starting. Because I have documented not just the successes but also the failures it means that what may have been a good idea early on in the project may have been removed later because it didn't work as well as expected. At least this way you can learn from my mistakes.
Here are the main points (as far as I know):
1/ Choosing & sourcing the motors
2/ Choosing & sourcing the wheels & gearing
3/ Choosing & sourcing an accelerometer (this helps with calculating the angle so the scooter can be controlled)
4/ Choosing & sourcing a gyro (the angle is needed so the scooter can be controlled)
5/ Choosing & sourcing a micro controller (this is what the gyro & accelerometer talk to)
6/ Choosing & sourcing a motor controller (this is what the micro controller talks to, so it can change the motor direction & speed)
7/ Wire all the bits up
8/ Program the micro controller
9/ Test what happens & make sure it all works before proceeding further
10/ Building a frame to support rider & wheel assembly
11/ Build a flat footplate to fit over frame
12/ Mount steering handle
13/ Mount batteries so the centre of gravity provides best performance
14/ Mount electronics & wiring
15/ More testing
16/ Build a steering mechanism for handle
17/ Test steering
18/ Maybe add lights & brake lights, reflectors etc
19/ Give it all a good coat of paint
This is day one & the first step in making a homemade DIY self balancing 2 wheeled scooter inspired by the Segway.
I can already see that even naming this project is going to be difficult, so I'm going to call this thing a scooter from now on until I can come up with something better.
I will be documenting & publishing each step, I am not able to work on this every day but I hope to get 3 days a week available for this project.
The Motors
There are many DC motors & many ways of connecting them to the wheels but as far as I can see wheelchair motors are perfect. They are designed for high torque & low revs but the best part is that they are already connected to the wheels, they have their own gearbox & the whole assembly is designed to be mounted easily. Why make a design difficult when you can bypass potential problems & use these motors.
Well there is one drawback, they can be expensive, if you look on Ebay then you will find many at between $50-$200 USD, $150 USD for a matched pair is fairly common. But if like me you need them shipped to another country then the shipping will cost a further $200.
I managed to pick up an almost complete wheelchair for $200 NZD in New Zealand but it took a lot of time & effort to find one. The chair is an Invacare PT2000 power chair.
As this project progresses we will find out if these motors are powerful enough to keep an adult balanced. The spec on each motor is 24v, 8A, & 120 RPM. This equates to almost 200 watts for each motor so lets hope it's enough.
Update March 2013. We've managed to source some motors & other electronics at a great price & have started to make up kits so you can make your own, check out the bottom of the Day 10 page.
Here's a video of how to check the motors, I added the video as it seemed that a lot of people had purchased wheelchair motors for different projects but found that each motor had 4 wires & they were not sure what to do with each wire. When I connect power to the electrical brake you can here it disengage with a click in the video, actually the wiring was loose so you can here it click a few times.
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