Medicycle - Urban Responder

We are living in the future, Medics now need motorbikes to navigate our congested cities but they no longer need two wheels

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"Its the year 2350, flying cars never really took off and so the world is gridlocked.

The Medicycle's use of revolutionary technology allows our emergency response teams to navigate traffic with ease whilst the latest up to date information is beamed directly to the riders heads up display from the central control centre."

The Medicycle is a self balancing twin tire unicycle that has been congfigured as a high tech first response vehicle, it uses an Arduino Mega in conjunction with an inertial measurement unit to keep itself balanced.

Useful information such as battery condition or even somebody's pulse can monitored with the heads up display which is wirelessly linked to the unicycle.

Panniers can be fitted to the Medicycle giving it the ability to carry additional medical supplies and equipment.


-----------------------------------------UPDATE NEW FOOTAGE -----------------------------------------

John Dingley Riding his "BLUE STREAK" machine somewhere in the UK, derived from his original unicycle entered into the 2014 hackaday prize, as you can see in the video it actually works rather well!

For more info visit -



A) Self balancing electrically powered unicycle design, resembling a motorbike but with just one wheel.

B) Configured as a first response paramedic vehicle of the future so it will carry basic medical kit and monitoring equipment such as ECG, Blood pressure cuff, oxygen saturation monitor.

C) Crucially, these will be integrated into the electronics of the machine and the data on the patient will be sent via a mobile data network to the web, for example so that a remotely placed doctor or co-ordinator can i) offer advice and ii) this allows a receiving hospital to have real-time medical data on the patient before they even arrive.......a form of telemedicine.

D) Helmet or head mounted monocular display of vital parameters using a high contrast OLED display and prism arrangement. These can be performance data of the unicycle (e.g. Tilt angle, remaining battery life, torque commends being sent to the motor) OR data on the casualty being attended by the paramedic.

Aim is to demonstrate all these functions in an integrated machine by the end of the competition.

Each main module will be developed in parallel with build updates on each, they will be listed under the following headings.






Self Balancing control System for Unicycle

Medical Pack and Monocular Display


a) The code for the self balancing on the Arduino Mega 1280

b) The code that runs on an Uno attached via serial link to the Mega, which then in turn runs the individual serial-enabled display modules on the front panel.

This lets the Mega spend all its time doing the self-balancing while the Uno can catch up running the displays in its own time.

c) The arduino in the wearable display.

d) The arduino that the e-Health module is attached to.

e) The arduino the GSM (mobile phone) shield is attached to.

Here is the location of this website.:

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  • Wireless Medical Data Transfer to the WEB

    Nick Thatcher09/15/2014 at 19:39 2 comments

  • Head Mounted Display Progress!

    Nick Thatcher09/15/2014 at 19:35 0 comments

    John and Dave are doing a great job, to get all the aspects of the project ready for the deadline is not easy task but we are almost there, this super cool head mounted display could have been a prize entry on its own!

  • Discovery Channel - Daily Planet

    Nick Thatcher08/28/2014 at 19:23 0 comments

    A couple of weeks ago a researcher from the Discovery channels Daily planet program stumbled across our 2min video for the HackaDay prize, they later contacted us asking if they could film the Medicycle in action.

    After altering a few holiday plans we met up in London and spent the day filming, the Medicycle perfomed flawlessly, the extra wide wheel even made it possible to ride across gravel without issue.

  • We Have Decals

    Nick Thatcher08/21/2014 at 22:09 0 comments

    The Medicycle decals and have arrived and they look good!


    Nick Thatcher08/15/2014 at 19:10 0 comments


    A “MediCycle” needs a medical pack obviously…………………….

    Cooking Hacks ( produce a biometric shield for Arduino and Raspberry Pi: the e-Health Sensor Platform V2.0.

    The e-Health Sensor Shield V2.0 allows an Arduino user to perform biometric and medical applications where body monitoring is needed by using up to 10 different sensors.

    This information can be used to monitor in real-time the state of a patient.

    Initially we will look at 4 basic medical parameters by having sensors in a pack built into the nose of the MediCycle.

    The leads and sensors for the following parameters will emerge from the front compartment of the MediCycle and be attached to the nearby patient:

    1. Blood pressure,
    2. Electrocardiogram (ECG),
    3. Oxygen saturation (SpO2),
    4. Heart rate.

    The data will be sent to the MediCycle rider via a pair of XBees (short-range wireless data transmitters) and displayed on the wearable display in front of the right eye.

    The data will also be sent via GPRS/3G mobile phone network over the web so it can be viewed remotely by a physician.

    Monocular display for the Medicycle Rider

  • Mini Update

    Nick Thatcher07/26/2014 at 08:20 0 comments


    Saddle panels made of marine ply 1cm thick. They bolt on to top and sides so thighs do not rub on tops of the wheels, always a good idea.

    “Café Racer” very dense foam for racing motorcycles used to make a seat pad that is comfortable but very shallow (2cm thick) , so feet can still reach ground. The sides are padded in much thinner foam, about 5mm.

    Foam is self-adhesive. Blue upholstery vinyl attached with spray upholstery glue, folded over the back of each panel and attached with staples using a manual staple gun.

    Saddle finished here. The two small fans at the front cool the OSMC power controller.


    Some photos here of the dashboard during “boot up” and then when machine is balancing. The values displayed are Angle of tilt (degrees), Torque to motor (0 – 100%), Battery voltage.

    Alloy panel made to tidy lower half of dashboard. Easily removed. Cereal box cardboard is great for making templates for things like this.

    Web-connected medical package:

    Now the basic self-balancing machine is progressing well, need to think about the medical package and where it will go. This will consist of an electronics package which will collect data on blood pressure, heart rate, oxygen saturation (pulse oximetry) and ECG as the initial parameters and send this to a remote physician wirelessly via the web.

    The electronics will be in this unusual shaped box which has been made to exactly fit a space behind the dashboard.

    Box for the medical electronics

    Inserting box behind dashboard

    Medical electronics box fully inserted behind dashboard

    The cables and leads for attachment to the patient will be stored in and emerge from, this area in the nose of the Medicycle.

  • Big Build Update

    Nick Thatcher07/21/2014 at 23:51 2 comments

    A lot has been going on since the last build update. There are no formal build instructions yet for a very good reason; with machines like this you have to build something and then iteratively develop it. This means the design deviates from the original, which was a best-guess at what would work, based on our previous designs.

    So, progress so far:

    • A version 1 Medicycle has been built well enough to allow testing of mechanicals and software. It does self-balance. You can ride it.

    • The first version with a single narrow tyre was almost impossible to ride despite the pivoting mechanism that allowed you to move your weight around over the wheel by pushing down on the relevant footpegs. Therefore the lower frame containing the entire drivetrain has been widened to take a second wheel in tandem on the same axle. Note that there is still only one motor, the two tyres turn together and are joined to each other. If the machine works well like this, then they can ultimately be replaced with a car wheel of similar width. However, as a test machine, this configuration gives lots of adjustment options.

    • The pivot system at rear of frame now has a locking bolt you can screw in which stops it pivoting if you so wish. Again this gives more options for practical experimentation. The previous Uni-Mig01 scooter John previously built was perfectly controllable with an 8 inch wide go-kart tyre simply by shifting your weight and adjusting speed in turns, so we are not sure we need the pivot in the frame or not. More testing will determine this.

    • The Arduino Mega 1280 balance controller now has both a digital inertial measurement unit (IMU) and also a more old-fashioned circa 2008 analog IMU as well. We can now compare the performance and reliability of each and we have software versions to work with each type of sensor package. The analog IMU’s may be out of fashion now but they simply put out a varying voltage proportional to tilt, which is quite comforting if you believe in the KISS (Keep It Simple – Stupid) approach to reliability.
    • The instrument pod has been changed and now has three LED 7 segment displays (which look cool) plus we have added a 20 x 4 row LCD backlit display as well (much easier to read in bright sunlight), which can display more data and is handy for debugging software.

    • The P, I and D plus “overallgain” control knobs seen in the previous update are now more widely spaced and a slightly retro-design with position numbers on each (they don’t go up to 11 though – yet). We could possibly later have a 3 position switch for the “overallgain” ride-quality settings labelled “soft,” “quite twitchy” and “insane.”
    • The twist-grip “accelerator” on the left handlebar is proving to be really useful in riding this machine. You can ride it by leaning forwards to make it go forwards, and back to slow down. However if you twist the handgrip, it alters the target angle from vertical the machine “aims for” when it is self-balancing. If you set this angle as a forward-tilt using the twist grip, then the machine starts to fall forwards, and the self-balancing software speeds up the motor to stop you falling over any further. The effect of this is to make the machine just tilt forward and off you go, no leaning required. If you back-off on the twist grip, it will lean back a little and slow down. This gives you good control of speed.

    • If we put a motorbike saddle on this it will be too high, wrong shape and feet will not touch the ground. Therefore the saddle will be made of marine ply so foam and a vinyl cover can be fitted, folded under and staple-gunned to the underside of the wooden panels. The padded panels will be arranged so they form an inverted U shape viewed from the rear. This stops your inner thighs contacting the tops of the tyres, always a good idea. The saddle will deliberately...
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    Nick Thatcher06/29/2014 at 21:32 0 comments

    The Medicycle build is progressing at lightning speed, The frame is mostly complete and John has almost completed the electronics required to make the unicycle balance, the instrument panel has even been 3d printed. 

    This is not the first machine we have built, if you want to find out more then visit this website

    Watch this space there is more to come 

    ANALOG INPUTS To Arduino Mega

    int forwardbackPin = 1; //analog voltage from a potentiometer I have connected to a "twist grip" on left handlebar.

    //It allows machine to be moved by adjusting the point at which it thinks it is "level" as well as just by leaning of the rider.

    //Not essential to have this will work fine just by leaning.

    int potPin = 9; //Potentiometer for adjusting the overall gain i.e. the "tightness" or "sloppiness" of the ride experience.

    int ppotPin = 13; //analog input 13 is from wiper of the potentiometer that adjusts p gain

    int ipotPin = 14; //analog input 14 is from potentiometer that adjusts i gain

    int dpotPin = 15; //analog input 15 is from potentiometer that adjusts d gain

    int batteryPin = 7; //analog pin 7 on Arduino has Vbattery/7 applied to it from the OSMC so we can work out the battery voltage.


    Nick Thatcher06/23/2014 at 22:53 0 comments

    The Medicycle is taking shape, John has done a fantastic Job of welding the frame together, the frame is primarily composed of steel box section and has some cool features... stay tuned for updates.

    When building a device like the Medicycle you have to design it to survive unexpected situations, like a TV presenter crashing it into the floor. This is why the Medicycle has a welded steel frame, its reasonably light weight and its strong enough to survive rough handling. 


    Nick Thatcher06/19/2014 at 21:54 0 comments

    On the Medicycle the wheel is one of the most important components, it certainly wouldn't work very well without it. 

    There are thousands to choose from and its easy to think that just about any wheel will do, so long as you can provide drive to it you should be able to balance, there are however a few things to consider before choosing.

    Size - this is probably the most important factor, if you are using a small wheel you save on weight but you are going to feel the bumps and this can affect balance and can even cause the unicycle to fall over.

    In this application a larger wheel is better, bumps are not going to have as much of an effect on the unicycle and the extra gyroscopic force exerted by the larger wheel will help you balance, remember though you will need to be able to sit on top of this and it helps if you can touch the ground.

    Drive - when buying a wheel make sure that you will be able to either bolt a sprocket to it or fix an axle, its best to got for the rear wheel of a motorbike as they will be designed to fit a sprocket, depending on the size of the sprocket you may have to find or make an adaptor plate.

    Width - its going to be easier to stay balanced on a wide wheel then on a thin wheel, however remember that on a unicycle you need to lean to steer, if the wheel is too wide it could interfere and you will end up with the same turning circle as a ship.

    The wheel we are using on the Medicycle is a 19" motorcycle wheel from a 1980 Honda CX 500

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kans.abhishek00 wrote 07/14/2016 at 12:33 point

hey bro

since i working on this similar project could help me in getting circuit digram of the ardino connection and the osmc connection diagram on my email id

if you can it would be great help to me thank you

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Adam Curtis wrote 11/06/2015 at 15:05 point

That's so cool!

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Kevin wrote 09/03/2014 at 11:56 point
Great project! I've been following you on Instructables for quite a while and have been impressed with your work.

If you don't mind me asking what does your potentiometer for overall gain actually adjust. I've been looking at the code and I only see one place where it is used. I know you indicated it adjusts tightness or sloppyness of the ride but could you expand a little more on what variables the knob effects and what this does to the output of the motor or anything it might control?

Keep up the good work!


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XenonJohn wrote 09/03/2014 at 22:14 point
Hi Kevin,
The code is a bit messy I know but it does work. Think of the Overall Gain potentiometer like this: You set the P I and D constants via three potentiometers and from these and the gyro/accelerometer inputs you eventually get the amount of torque to be sent to the motor (updated 100 times per second).
The Overall Gain potentiometer simply takes this total value from the previous calculations and allows you to multiply it by 1, or maybe 1.2, or maybe a little more or a little less.
It is a crude way to adjust the feel of the machine just using one knob, but without altering the ratios of the P, I and D constants with respect to each other, the ratios of the P I and D to each other can remain unaltered therefore. Think of the P I and D constants as fine tuning of the balance characteristics of the machine, and the Overall Gain potentiometer as a kind of "volume" knob. It just makes the ride quality "tighter" or "mushier" by turning one knob, once you have (earlier on) managed to get the P I and D values right by a lot of trial and error.
Hope this helps, clearly it not particularly vital to have such a control knob at all.

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Kevin wrote 09/04/2014 at 11:40 point
Thank you very much for the explanation!

I know you are very busy and your free time is limited.

Your efforts to share your knowledge and experience are appreciated.

Thanks again!

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voxadam wrote 07/30/2014 at 00:29 point
How are the Medicycle and Nick's Raptor related? Is the Medicycle the evolutionary step? Do you expect to see an increase in top speed, carrying capacity, distance? Do you have target numbers for the Medicycle? About what does it weigh in its current incarnation?

In the current "dicycle" configuration is the Medicycle able to balance itself at rest without a rider?

One last thing (for now), why did you choose to use MY1020z motor instead of a hub motor? Hub motors are far more expensive, so, I feel reasonably comfortable assuming that was at least part of the decision. That being said, if all things were equal would you have gone with a hub motor?

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XenonJohn wrote 08/09/2014 at 10:28 point
Many questions so many answers........

Nick's Raptor used an analog IMU and code I had written for my self balancing skateboard, modified for a one-wheeler. That sent motor speed commands via a serial link to a Sabertooth motor controller that generated its own pulse width modulated (PWM) power to the motor.
The mechanical design of the Raptor was extremely neat and all done by Nick, while still a teenager I might add.

At the same time I experimented with getting the self-balancing code working with a digital IMU as the analog ones are now harder to find, and also speeding up the (too slow) 500Hz PWM of the Arduino to a faster rate so I could then use it to drive an OSMC power controller which can handle huge currents. Having achieved these upgrades I tested them out in the Uni-Mig01 scooter which was a monowheel Vespa styled scooter with a really wide Kart tyre.

This control system is now in the MediCycle with further improvements.

This retro-styled scooter worked fine, the new machine is obviously styled like a motorcycle as it is much cooler way to go. Top speed is limited (for now) to reduce broken bones while I develop and debug it. Top speed could be much higher limited only by the courage of the rider and power/drive system. Carrying capacity is an interesting issue as again so long as motor has enough torque to correct a tilt, most of the time the weight acts vertically down through the wheel, so actually is a very efficient way to carry loads, like those women who choose to carry huge loads on their heads, rather than on their backs.

You can swing top part of frame left/right a few degrees as in the "enicycle" unicycle ( to move your centre of mass left/right of the wheel. This should help with steering and the Raptor did not have this. This feature is still being tested.

The twin tyred-wheel is functionally equivalent to the really wide tyre I had on the Uni-Mig01 scooter in terms of contact area with ground. Could be replaced with a wide car rim ultimately. You turn by leaning left/right and the inner tyre compresses slightly, this means its diameter is functionally less than the outer tyre, so machine will turn. As a means of steering it worked fine on the Uni-Mig whereas with a single narrow tyre the Raptor needed a lot more skill to steer.

Distance again is theoretically large, as when balanced and running on level ground these machines draw very little current; just to overcome rolling resistance of the tyre, drivetrain, and wind resistance i.e. less than an equivalent 2-or-more wheeler. The extra (large) reserve power (i.e. potential available torque at the wheel) is held in reserve for when you are falling over or going up a hill, when the extra power is required rapidly and effortlessly.

I have tried hub motors. Most nowadays are brushless. A cheap e-bike brushless power controller will not do as it has to be able to go as fast backwards as forwards, and switch between the two rapidly when balancing stationary. Suitable power controllers are available but expensive and indeed I have built a brushless motor Segway type machine with a very expensive Roboteq controller in the past

The main problem is that hub motors do not generate much torque at the wheel when stationary or at slow speeds (as they are optimised usually for bikes), which in a self-balancer is exactly when you need high torque the most. For a self-balancer it has to be able to generate high torque at the wheel effortlessly else it will not self-balance. Therefore I chose an OSMC (brushed) motor controller which at a reasonable price can handle 150Amps continuous, and a low cost but hefty Chinese motor that has a 1:6 reduction gear built in. This is required when using a motorbike wheel as without it you would need a huge chain sprocket on the wheel to get the correct gear ratio and torque (turning force) at the wheel.

I have learned about appropriate motor power requirements and gear ratio requirements for self-balancing simply from experience building these things. There is no "textbook" which is why this hobby is such fun. You learn something new with each machine you make.

It will balance itself at rest with no rider on it (with just a thumb on the deadman button of course)!

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PointyOintment wrote 07/28/2014 at 18:42 point
How does it turn?

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XenonJohn wrote 09/02/2014 at 12:33 point
We spent a whole day testing it recently on coarse gravel and also tarmac for a TV company. The steering pivot at the rear end that allows the upper frame to swing a few degrees to let you shift your weight to one side or the other over the wheel was locked solid for that day with a bolt and the handlebars were solidly welded to the frame. We found it can easily be steered on tarmac by just shifting your weight around so long as your turns are long and graceful, on gravel it took some learning how to do it but it was also possible. Tyre pressures make a big difference too (it would be really cool to one day make a machine steered by a computer continuously altering the tyre pressures on the fly, like some military vehicles can do to adjust to different terrain).
The steering linkage is now being worked on using the lessons learned from this testing day. Expect an update soon. As in previous posts, you learn the most about this subject by building and real life testing.

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XenonJohn wrote 09/20/2014 at 16:43 point
It now turns by turning the handlebars. This swings the upper bodywork to the left or right allowing faster and finer control of weight distribution to left or right of the wheel. As your weight shifts the inner tire compresses so its diameter is less than outer one, so you turn.

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rapfg4 wrote 07/07/2014 at 21:52 point
Very impressive progress in such a short time!!

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XenonJohn wrote 07/21/2014 at 22:05 point
A big update coming very soon. It runs and we have been developing software and redesigning hardware as a result of good old fashioned human experimentation! I have a Kevlar helmet which comes in handy.

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JackRC wrote 06/24/2014 at 07:49 point
Just wondering how are you going to brake??
I mean if you hit the brake hard you will run over bar and hurt yourself really bad like I did a few months ago. I broke my neck and still recovering :(

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XenonJohn wrote 06/24/2014 at 23:35 point
Hi Jack,
To slow down you lean backwards. The machine thinks it is falling over backwards so slows down, and if you persisted it would even go into reverse. All energy from this goes back into battery by regenerative braking. To go forwards you lean forwards, but alternatively there is also a twist grip handle on left handlebar then when twisted resets the target "balance point" so machine leans forwards and off you go. It acts as a twist-grip throttle in effect. I could develop something similar to make it slow down also.

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XenonJohn wrote 06/19/2014 at 17:23 point
There are electric vehicle drag races so it would be cool to set up a new class for electric unicycles and have an inaugural event!
Am trying to build in a steering geometry similar to the one Aleksander Polutnik used in the enicycle. This should in theory make it much easier to learn to ride. We shall see.

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rapfg4 wrote 06/19/2014 at 16:36 point
Yo, I am also currently working on a single wheeled, DC powered, self balancing motorcycle and we should set up a race when everything is complete. It would be a first ever!!

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loriffic wrote 06/19/2014 at 15:57 point
Awesome project!

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Adam Fabio wrote 06/16/2014 at 05:59 point
I'm a sucker for a self balancing vehicle! Thanks for entering mediacycle in The Hackaday Prize! Don't forget about the connected portion of the prize - though you've got plenty of technology already with your wireless heads up display!

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