Making sitting anywhere possible

We’re going on a holiday! For the first time as a family we are traveling abroad. Up to now, between covid and the logistics of traveling with everyone, we never ventured on a plane as a family. We’re not making it easy for ourselves either, our first trip is to the mountains in France!

The logistics of traveling to a mountain location with someone in a wheelchair are complex. The top of a mountain is rarely an accessible spot, but we got amazing advice from Mountains For All, an organisation that ensures that the main logistics of a trip to the mountains are possible for anyone, of any ability. They advise on the resort, confirm accommodation accessibility, help with airport transfer arrangements and liaise with the ski resort to let them know you’re coming and, most importantly, ensure that the ski school can provide sit-ski (skiing for people in wheelchairs). I’ll hopefully write more about this later and share some videos from the trip with Ronan. I’m sure Ronan will be like Trevor Kennison in no time (watch the video, it is inspiring).

All the logistics of getting around are sorted (hopefully) the only thing left is how to make sitting comfortable and accessible for Ronan on the trip.

The seating problem: A portable alternative to an activity chair, that’s 20x cheaper than alternatives.

Ronan has a push wheelchair that we will bring on the ski trip. At home he doesn’t use the wheelchair much in the house because it’s big and not quite at the right height for sitting at a table. Instead, he uses an activity chair. An activity chair is a height adjustable chair that can be pulled up next to a table. It is weighted to have very low centre of gravity which makes it very safe and possible to raise up quite high (standing height), but also makes it incredibly heavy (easily 50kg). It’s more comfortable than the wheelchair and slightly easier to manoeuvre in the house.

The reason Ronan needs a special chair in the house is so he can reliably stay upright. He can’t move his arms or hands to balance himself, so he will tip to one side if he is not in a chair that has lateral supports. He also needs a headrest when seated and requires a lap belt to ensure he doesn’t tip himself out.

The challenge for our holiday is that we can’t bring the activity chair. I am worried that this will mean that some locations will be inaccessible e.g. a busy restaurant with small gaps between chairs, or locations with benches instead of regular seats will be tricky.

The available seats on the market are typically designed like this Go seat. There are a couple of downsides to this design. First, the lateral supports are not very rigid and secondly support comes from the fact the child is strapped into the seat using a four or five point harness. There is results in very limited possible movement once seated.

We have tried these with Ronan, but he doesn’t find the five point harness comfortable and, if he is not securely in the harness, the side supports don’t work.

Therefore, over the last couple of weekends I set to work on the challenge of designing some form of seat that would work for Ronan.

The requirements were:

1. Portable — need to be able to bring it on holidays with us
2. Lateral supports — needs to hold Ronan at the sides
3. Head rest — support his head when he leans back
4. Lap seatbelt — belt to keep him in the chair
5. Seat at 5–8cm higher than a standard chair — this is the additional height needed to be at the correct height table height
6. Cool — more a nice to have

Version 1: Triangular design

The gist of the idea I had initially was to build something like a car seat that Ronan could use i.e. it would be an attachment that you can put on a standard chair and it is fastened to the chair with a strap.

The second challenge was around how to make the lateral supports for the chair. The supports have to be strong so that Ronan can lean his full weight against them. I had this idea that a triangular design could be really cool so I started to pull together an initial prototype with things I had in the shed.

Here’s the first version of the seat that I built.

It uses an old piece of carpet as the upholstery.

The good things about this seat are:

1. It has very strong side lateral supports
2. The headrest and seat position are in the right places
3. It is light and I think it is quite a nice design
4. It is easily attached to any standard chair in the house

But,

1. It isn’t portable — it’s just a little too big

Ronan found it comfortable and he was quite happy to sit on it for a long period of time.

Version 2: Making the chair portable.

Portability became the next big challenge. I have a desk in my office that is CNC cut plywood that just slotted together and it gave me the idea that maybe that sort of design would work for the chair.

Here is the design sketch.

The goal is that it takes the shape of the activity chair with side supports and head rest, but slots together. Each side is cut from a single piece with three cross pieces, two on the seat and one on the headrest that give the chair its shape.

The chair is secured to a standard chair with a strap around the base, and we can include a lap belt to secure Ronan in the chair. Ronan has scoliosis so a chair back wouldn’t get used, but you can imagine how that could be included easily.

And… here it is.

I don’t have a CNC machine so I had to cut the ply with a jigsaw, but it came out ok and slots together nicely. I used a router to make slots in the plywood for straps and lap belt and I used a 3mm foam to soften the surface.

I’m still trialling some seat covers. Right now, a small cushion works best, but I have an idea of putting something that slides over the two side panels to form the seat. I just need to invest in a sewing machine.

I have also ordered some more padding for the headrest to make it a bit more comfortable.

Conclusions

This worked really well! The seat achieves the requirements really well. But, it also achieves something else really important that I hadn’t thought about before I started work on this. The cost to make a seat. I guess this was an implicit requirement. I think it cost about 30euro excluding labour and tools. I can make 3 more of these seats and just leave them places like at grannies house, or at school so that Ronan always has a comfortable place to sit. Once he grows out of this seat, I can make him another the next size up. The design is so great I think I’ll CNC the next ones and maybe experiment with different materials.

Most things on the market for people with special requirements are designed to be infinitely adjustable. In practice, it is adjusted once to the user and then used in that position for months / years. A design like this has no ability to be adjusted, but if it is designed for the user that doesn’t matter, and then you don’t have to carry around the payload of all the adjustable functionality.

I’m optimistic that a design like this could be a really good solution for people that can not afford an activity chair. Take some measurements of the individual, put through some software and cut out the design to fit the user and you have a solution that works for the individual.

Future improvements

There are some downsides that I would love to figure out over time how to address.

1. The centre of gravity can be high. This depends on how exactly the chair is constructed, how the sitter sits on the chair and how much they move in the seat. The simplest solution for us has just been to make sure the chair is pushed under a table. The lateral supports then hold it in place.
2. Transferring from wheelchair to chair. Right now Ronan is <20kg. As he gets bigger, it will be harder to transfer Ronan to a chair that doesn’t have wheels to easily move him into position.
3. Software input. I think it could be a cool project for someone to build some software that translates some basic measurements that define the needs / shape of the chair and translates them into a CNC design that can be cut to order for the individual.