Starglider: Eco-Friendly and Easy Motorization for Wheelchairs

Imagine what you would do if, from one day to the next, you were no longer able to walk and move around freely. Faced with this handicap, many constraints arise, and climbing a slope becomes as hard as climbing a mountain.

In my high school, there was a lady working in the administration who was in a wheelchair. What's more, as part of the Engineering Science specialization, we had to carry out a project using the knowledge and skills acquired during the year. So I came up with the idea of developing a universal system for motorizing all types of wheelchair, without the need for difficult or time-consuming installation. I've called it the Starglider.

One of my wishes for this project was also to emphasise the eco-responsible aspect. So I'll let you discover how this project combines technology, social and eco-responsibility.

Hardware :

1. Motor Brushless (6374, 170KV, 2800W, 24V/36V), buy here
2. Batterie Lipo 2S 3000mAh, buy here
3. ESC and programmation board, buy here
4. Seeeduino Lotus board, buy here
5. Slide Potentiometer
6. Wires

Production equipment :

1. 3d printer
2. Some screws ans nuts
3. An aluminum axle (12mm of diameter)
4. Inserts
5. Your hands and your mind

The first phase consisted in selecting the electronic components. For the electronics, I recommend using a large brushless motor, as this is a motor capable of turning quite fast while maintaining high torque. The motor is powered by a rechargeable lipo battery. To control the Starglider, you'll also need a Seeduino board, an ESC capable of translating the analog signal from a potentiometer into a sinusoidal signal usable by the motor, and a potentiometer.

Then I started thinking about different ideas for the engine's supporting structure. The challenge was to make a strong, lightweight structure out of PLA, which is a bio-sourced material. 2 main ideas stood out:

1. create a 3rd wheel that attaches to the wheel axle
2. create a backpack-like structure, which would attach to the back of the wheelchair on the bar that normally pushes the wheelchair user up slopes.

The first solution had the advantage of guaranteeing optimum stability and thus safety on slopes, by preventing the wheelchair from tipping forward. However, this solution had to be abandoned, as it did not allow the user to turn around in narrower spaces.

I therefore opted for the second solution, which was certainly the best compromise between stability and mobility, while allowing the user to remove and reattach the system quickly and easily at will. This was very useful for my user, for example, as she had to fold and unfold her chair every time she took her car. This solution is universal and adapts to all types of wheelchairs, making the system more versatile and adaptable. Moreover, the components used are standard and easy to find anywhere.

Nevertheless, it might be worthwhile opting for the first solution, depending on the user's constraints.

To ensure the user's safety and comfort, it's important to consider the wheelchair's balance when the system is in place, and how easy it is for the user to put the system on and take it off.

To attach the system to the wheelchair, we again had 2 solutions to choose from.

1. a box containing the system, which slides onto an aluminum rail screwed securely to the back of the wheelchair
2. a hook-shaped structure which attaches to the bar on the back of the chair and is secured by a pin.

But as mentioned, it was crucial that the system could be easily dismantled. For more regular use, I'd still recommend the first solution.

In order to guarantee the system's high resistance and avoid any risk, numerous simulations and optimizations were carried out, until we arrived at the final system. The part resists various types of shock and deformation due to the weight and rotation of the motor. I used, for example, the principle of composite materials, cutting the part into 2 parts and connecting them with a single long metal screw. This will also help you during printing, as it requires no support.

For the link between the motor and the wheelchair wheels, I chose to connect the motor to an aluminum axle using pulleys and belts that can be 3D printed or ordered from the HPC website. The ratio I recommend is ... Rotation is then transmitted by transmission rollers attached to the end of the shaft.

Once the system had been correctly modeled, it was time to move on to the programming phase. The value read by the potentiometer must be linked to the motor speed. This allows the user to control the speed.

Paste this link in Preference in your Arduino windows : https://raw.githubusercontent.com/Seeed-Studio/Seeed_Platform/master/package_legacy_seeeduino_boards_index.json (see media) and choose "Seeduino Lotus" in Select Board (see media). Then plug in the card without it connected to the battery, to prevent it from shutting down your computer, then upload.

For safety reasons, I first made a LEGO model, in order to check that the project was feasible and that everything was functional. My prototype is only in Lego but I've designed for you the real pieces, so that you can do it for real.

Each part can then be 3D printed without support in PLA. Personally, I bought a belt (RPP5/180/9 on HPCeurope), in order to guarantee a good connection between the 2 belts. However, the strap for the LEGO miniature model has been printed in 95A TPU. So it is also surely possible to do this for the full-size belt.

IMPORTANT : Print "Transmission Roller" twice !

To finish, all we had to do was assemble and test everything. To assemble all this, we will need our hands, screws, nuts and screwdrivers.

1. Add inserts in all the holes that will accommodate screws, so that our part is as strong as possible
2. Attach the largest of the belts to the axle
3. Assemble the 2 main parts "StarGlider V2 - P1" and "StarGlider V2 - P2" like a puzzle around the aluminum axle and secure this with a 70mm long and 4mm diameter screw, then a nut. We attach the motor to the intended location using the 4 screws supplied with the motor
4. Attach the second small pulley to the motor axle. I strongly advise you to secure this by aiming through the inserts
5. In the same way that the pulleys were fixed, attach the transmission rollers to the end of the axle, previously cut according to the width of your wheelchair
6. Discreetly fix the rest of the electronic components in the back of the chair, apart from the potentiometer, which must remain accessible

Take advantage of it now to rest during the slopes, I hope that this Instructables will have been useful to you, either personally or by helping those around you.

Tips : For better adhesion between the transmission rollers and the wheels, you can glue pieces of punctured inner tube around the rollers.

Once again, I wanted to emphasize the sustainable development aspect of this project, because it is something that is close to my heart. Indeed, this notion can be divided into 3 pillars: Social, Economic and Environment.

The project enhances mobility for people with reduced mobility while being easy to assemble and use, which improves the daily lives of wheelchair users by providing them with greater mobility. The idea of ​​this system is to help those who need it and this is also what I am trying to do by writing this Instructable. I sincerely hope that it can be useful to you. In addition, creating this system allows you to make great savings and all my work is Open-source (According to my estimates, you save more than €3000). Finally, many measures have been taken to take into account our impact on the environment. Of course, plastic pollutes, but we have chosen a bio-sourced and degradable plastic. In addition, all the components are replaceable in the event of a breakdown, because they are available on the market, just like the screws. And finally, everyone can do it themselves without importing too much material from China, etc.

If you've read this far, you're almost perfect. If you want to support me, just leave a like or a comment and you'll be absolutely perfect ;)

I'll be curious to see your own real system ! Text me if you did it !