[Irene Sans] and [Alvaro Ferrán Cifuentes] feel that electric wheelchairs are still too expensive. On top of that, as each person’s needs are a little different, usually don’t exactly fit the problems a wheelchair user might face. To this end they’ve begun the process of creating an open wheelchair design which they’ve appropriately dubbed OpenChair.
As has been shown in the Hackaday Prize before, there’s a lot of things left to be desired in the assistive space. Things are generally expensive. This would be fine, but often insurance doesn’t cover it or it’s out of the range of those in developing nations. As always, the best way to finish is to start, so that’s just what [Irene] and [Alvaro] has done.
They based their initial design on the folding wheel chair we all know. It’s robust enough for daily use and is fairly standard around the world. They designed a set of accessories to make the wheelchair more livable for daily use as well as incorporating the controls.
The next problem was locomotion. Finding an off-the-shelf motor that was powerful enough without breaking the budget was proving difficult, but they had an epiphany. Why not use mass production toy crap to their advantage. The “hoverboards” that were all the rage this past commerical holiday season were able to roll a person around, so naturally a wheelchair would be within the power range.
They extracted the two 350 watt hub motors, batteries, and control boards. It took a bit of reverse engineering but they were able to get the hub drive motors of the hoverboard integrated with the controls on their wheelchair.
In the end they were able to cut the price of a regular electric wheelchair in half with their first iteration and set the foundation for future work on an open electric wheelchair system. Certainly more work could bring even better improvements.
As soon as I saw those hoverboards, I knew those motors had enormous potential, they’re powerful, easyish to set up, and available. Glad to see the bunch of projects featuring them, this seems particularly noble.
The work people are putting into electric wheelchairs is great to see. I used to repair chairs and scooters and there is lots of room for improvement and economies to be made
Unfortunately here in Oz I believe there are very strict regulations on what can be used as a wheelchair. My son looked into making them some time ago and the red tape is oppressive. You may get away with making one for personal use but definitively not for resale. The one he had for our grandson was grossly expensive and it was not even motorized.
There is a great need for a cheaper option!
Indeed if able to obtain cheaply can result in a project that can help a lot of people.
It would be of interest to determine the motor’s efficiency at various speeds & mass in transit,
determination can offer best fit for battery vs motor life too ?
Well done
I can see someone adding a few Kinect sensors, maybe a flat bed scanner head for the floor and closeups. Send it off around the contryside like a Google Street view mapper. Have it come back to charge when it’s batteries get low. With some route planning and a bucket of cheap sensors, if you’re lucky you can pick up anew okay electric wheel chair for £100. Makes for a great autonomous robot.
Maybe counting ripe apples in an orchard with blob detection or planting seeds neatly on mass.
Worthy work…
Not sure I like the driven wheel placement on the top pic though, seems like it would inhibit certain maneuvers, like sidling up curbs when necessary. 95% of the time it’s probably fine, but that extra 5% that the wheelchair design has evolved to deal with, might be compromised.
I would tend to want to do something like use boat trailer rollers driving the wheels in the top rear quadrant. Issues could happen with rain and mud, but they can happen at the tire/road interface also. Should have a raise/lower clamp to remove drag if you want to manually wheel it.
For a control system on a converted manual wheelchair, what would be cool is power assist mode, where pressure sensitive gloves, or maybe sensor on the wheel handrails (What’s the right name?) detects grip and push and adds motor assist to it, then it would be somewhat intuitive to use for an experienced manual chair user, force amplification.
Thanks!
The top image is from the previous iteration, in the last one we actually removed the larger wheels and kept just the driving ones. While this compromises the manual driving (like in most electric wheelchairs), it makes the chair able to rotate on the spot, which we deemed much more necessary.
As for the control method, we’re designing a board with both BLE and plenty of GPIO/I2C/SPI/UART pins to enable the user to implement the system/sensor that works best with them :)
Yeah, the swivel on the spot ability is a good benefit, probably allows operation in tight quarters not designed with chairs in mind.
i would go with 2 direct drive brushless hub motors(with hall sensors), meant for bicycles ( direct drive so you can use regenerative braking), 2 regen capable brushless motor controllers with reverse functionality, and a couple joystick style controls for forward/reverse on right/left for steering, perhaps with little red buttons on top to engage the regenerative braking. (not sure if this sort of throttle control is readily available, probably have to build it from scratch) (i’ve already well exceeded the 270€ budget, but i’m talking more of a drag-racing model open-wheelchair. if you just want to move, at walking speeds, pick up a defunct cordless drill or 2 and get to hacking.) as for battery, you can go with the conventional lithium, but i’d like to see what https://www.youtube.com/user/RobertMurraySmith ends up making, he makes it seem like anyone can just take everyday garbage and make supercapacitors with higher energy density than the best lithium batteries.
I didn’t think those really got close to even lead acid for energy density yet. Amaaaaaazing for capacitors, but still a bit off batteries. However very good high current buffer for those chemical technologies that are slow to ramp up.
some of his stuff is technically a rechargeable aluminum air battery
This is a great idea. Nice work. :)