Ninebot one - tear down to fix a puncture

The Ninebot one that we have, was lying idle for a couple of days due to a puncture in the tire. We are demoing the unicycle at Construkt fest here in Bangalore. So we decided to fix the puncture. 

Overall it took us close to 4hrs to fix the puncture. Apparently it seems we have to tear down the entire unicycle to repair a puncture. This was super painful. This time includes 2 trips to the puncture shop, tear down, putting it back and taking pictures in between. 

The picture above shows all the parts in Ninebot one teardown

Following are roughly our thoughts regarding the design of the Ninebot one - what we liked and what we did not. 

To get access to the wheel, the pedal needs to be removed. We had a lot of trouble removing the pedal. There is a pin that needs to be removed to remove the pedal. The pin was jammed on one side. That took us a lot of time to pull that out. 

There are a bunch of bolts that needs to be removed to remove the casing on one side. Those bolts were obvious except for one side. This one set was close to the pedal and hidden behind a pad that was glued to the plastic casing. The image above shows these sets of bolts that I am referring to. 

These set of bolts also came with a split washers as shown in the image above. They are 4 in number on each side. These split washers makes sense for this bolt as these bolts attach the body of the unicycle to the wheel axle. This is one of those critical joint where any loose connections on this joint would introduce errors in gyro readings and make the unicycle misbehave. 

The rest of the bolts are without split washer. Couple of things that we liked - 1) They are using bolts instead of screws. This means we can afford to remove and assemble the unicycle a number of times. 2) All structural bolts are allen bolts. Star screws are used for fasteing covering plastic members that adds aesthetic to the device. So if you are removing an allen bolt, you are most likely removing a structural bolt. You might definitely not want to loose these bolts. 

Once these bolts are removed, the casing on one side came of pretty easily. When one side, is removed it looks like the image above. 

Our guess is that for fixing the puncture, this should do. But since we are half way though a tear down, we decided to go all the way. Moreover this is the second trip that we are making to the puncture shop - was not in a mood to make a 3rd trip in case if this level of disassembly was not sufficient. 

So we removed everything, so that finally it was only the wheel assembly (tyre & hub motor). That we took to the puncture repair shop and got it fixed.

Couple of other observations made 

There was a ton of dust on the circuit board. We are super surprised to find this amount of dust on the circuit board. We are even more surprised that it still works. It looks like the Ninebot was not designed to work in the conditions in the farm/India. The typical places that we drive though has a lot of loose dust.

Weirdly there are 3 openings into the wheel cavity. You can see them in the image. This is where the dust in entering the circuit board cavity. When you drive though sandy/dusty area the wheel picks up a lot of dust, which eventually ends up here. 
The battery pack cover casing is biting into the battery pack. This is bad for the battery pack. If it punctures the battery pack, the battery pack will most likely catch fire. This is not good at all. For the time being we left it as it is. We should put a double sided tape at those points.

Firefly Developer Meetup at Maker's Asylum

This is a quick minutes of meeting of the Firefly developer meetup that we did at Maker's Asylum on 27th Jan, 2015. 

Talk on the open source electric unicycle project, Firefly Unicycle. 

Speaker: Alex JV Co-Founders, Makeystreet. 

What is an electric unicycle?
What is this project about? 
What are they trying to achieve with this project? 
How can they get involved? 

We bought an electric unicycle with us, so that people could try it out. We had roughly about 8-10 people who turned up. Looking forward to having the first build group for electric unicycle at the Maker's Asylum.

Prior Art / Setting bench marks

We are doing a prior art study to understand existing electric unicycles in the market. To do the study we have chosen 5 different unicycles based on various parameters. Our first internet based study showed that the primary variations are in motors capacity, diameter of the wheel, size and chemistry of the battery pack. Based on possible variations we have placed order for 5 unicycles as shown in the image above. Once we get the unicycles in our possession we will know first hand how does all these parameters feel like in real world. This will help us design our open source unicycle better. 

We have already got Freefeet in our possession. Playing with it now. We will be opening it up as soon as the holiday season is over. 

Best part - We now have a lot of unicycles to play with. Want to try them out? Come over to the Jaaga farm on Sarjapura road. 

Specs of the unicycle that we are getting:


48V 1000W motor, 122Wh LiFePO4 battery, 18" wheel

Detailed tech specs -

Freefeet unicycle

500w, 60v,3.5Ah, lithium-ion battery (130wh), 35cm diameter [ brand of battery is Samsung}

Gotway 14"

Image credits -

10.8kg, 14inch wheel, 60V 500W motor, 340Wh Panasonic Lithium-ion battery. Bluetooth connectivity. 

Gotway 18"

Image credits -

14.8kg, 18inch wheel, 60V 1000W motor, 700Wh Panasonic Lithium-ion battery, Bluetooth connectivity.

Ninebot one 

image credits -

12.8kg, 16 inch wheel, 1500W motor, 240 Wh Lithium ion batter, Bluetooth connectivity

We have five 800 Watt motors !

We now have five 800 Watt 48 V brushless motors. Thanks to BSA for sponsoring the motors and thanks to Ather Energy for getting it on our behalf. 

That leaves us with 5 motors that we know are really powerful but with no specs. Challenges ahead of us :
1. Get the motor to work
2. See if we can get data from the position encoders/hall effect sensors in the motor. Does the motor even have sensors?
3. Hopefully the motors does not have flywheels inside them and are bi-directional. We hear that some motors used in electric scooters are uni-directional. 
4. Find out how to attach wheels to this. Hopefully we should be able to get off the shelf wheels. 

We might be opening them up one of these days. Will post updates for the same. 


Firefly basics of self balancing - first workshop

We build a small robot to understand and implements the basics of self balancing. The robot works on the principles of self balancing. Here is a short video of it working. Since its a small robot, we are calling it Firefly Larvae :)

If you want to know the principles of how the self balancing robot works, check the documentation for the robot here -

Here is video of us testing the self balancing code - 

Other than the organizers we had 14 people turn up for the discussion. 10 people were present for the workshop. 

Check out the pictures from the day

The documentation for the entire project coming up very soon - Hold on tight. 

Firefly Unicycle at Reva

On 20th Nov, we went to meet the awesome people at Reva at their factory at Bommasandra Industrial Area here in Bangalore. We went their to introduce them to the electric unicycle. Nothing much, just show them the unicycle and possibly get some feedback on how we can take this forward as an open source hardware project. 

The response for the unicycle was immense. People were crowding around it. Here are some pictures of it. 

Team Reva seems excited. They mentioned that their engineers would love to answer questions that this hardware community would have. 

Firefly unicycle at Intel hackathon

On 22nd Nov, Intel conducted its hackathon in Bangalore as part of its roadshow. They were giving off a lot of free hardware. I totally wish I was a participant. 

We were there to demo the unicycle and get some developers interested. We did not get a lot of pictures but here are some of them. We had a lot of people try them out when they wanted to take a break from the hacking session. 

Above are some of the pictures taken at Intel Hackathon of people trying out the unicycle. 

First developer meet for Firefly Unicycle in Bangalore (minutes)

We had our first developer meetup in Bangalore at Jaaga. 

Quick minutes of meetup

1. Getting to know each other

We had 8 people who showed up and we were 3 organizers (Freeman, Numaan & Alex). So in total we had 11 people.

2. Intro to the project

Above is the presentation used for intro section 

Our objective is to build really a strong community of hardware hacker in India.

2. Understanding the overall technical architecture 

We had a discussion on the basics of the tech - Find the reference slide here.

Further the discussion was based on a bunch of youtube videos. Some of them include:

Inverted pendulum basics -

Stunts on a unicycle -

Electric unicycles are already popular in china -

Electric unicycles used offroad -

3. People got to try a Unicycle

We have one electric unicycle - Freeman's. The attendies got to try that and get a sense of how it works and feels like. We are planning to get a couple more of electric unicycles for testing and development purpose from China. 

4. Getting started 

The system design for the open source project will be hosted on Makeystreet -

If you were at the meetup, pick the subsystem that you are interested and let me know, will add you to that subsystem. 

If you were not at the meetup and would like to contribute to the subsystem, let me know when subsystem are you interested in and we will take it forward from there. 

5. Next steps

  • Getting a couple of self balancing cycles from China to open up
  • Doing an arduino based workshop on inverted pendulum at workbench project
  • Getting the first version of the unicycle up and running 
  • Setting up developer communities in other part of the city
  • Creating a video for the project

Alex (@alexjv89)