Concepts

Concept 1 exoskeleton

The first concept that was created is a partial exoskeleton. The exoskeleton consists of two supports for the knees, which can be connected to a different mechanism. This mechanism would be in between the knees and it would make it possible for the knees to move apart from each other. This is something that was really desired by the participant since it is something that he would like to train, but can not do on his own.

The mechanisms that would be used in these concepts are hydraulics. First, the participant would put the supports around his upper legs and lower legs, using the straps shown in the drawing. This would make sure that the supports are placed next to the inside and outside of the knees. In the knee cavities, there would be a cushion that makes the product more comfortable for our participant. After that, the user would get up from the wheelchair. When his legs are stretched, the hydraulic system would make sure the legs can only stretch out further, but not go back to the bended position. This would make sure that his knees won’t cave in while standing. When the participant is standing, he would attach a system to this knee support. This system would go in between the knees. The mechanism allows the participant to create some space in between the knees. Over time, this distance can be adjusted to what the participant can handle. This would make sure that the muscles in his legs that are shortened would stretch out, and this would result in less (intense) spasms. A summarizing storyboard of how this concept works can be seen below.

After creating this idea and the final sketches, we started working on a very simple version of the prototype. This way, it was easier to reflect on the concept and to show it to the participant to see what he thinks. Pictures of the prototype can be seen below.

Concept 2 horse saddle

The second concept we created is based on the idea of having weight support. One of the things our participant told us was that he would like the product to support some of his body weight, so there is less weight and pressure on his legs. After doing multiple ideation sessions (see chapter ‘Ideation’), we thought of a system that could be used as a standing support or chair, which would still help the participant to stretch his shortened muscles. In the picture below, a first visualization of this concept can be seen.

First, the chair would have to be adjusted in its lowest position with the smallest width that it can take. Then it would be possible for the participant to get out of the wheelchair and position himself above the product. Once he has done that, the product can be adjusted to the desired height. Once the product is at the correct height, the participant can adjust the width of the saddle. This makes it possible for his muscles to stretch as much as he wants to / is able to. Over time, this could be adjusted again.

This was then adapted and worked out to the following concept drawing:

Concept choice

Participants feedback

Concept: exoskeleton

At the beginning of the project, the participant let us know that he really liked the idea of having an exoskeleton. The idea was that this would give him more support and allow him to stretch his muscles at the same time. Working out this idea, it turned out that this was very complicated to accomplish, because there are a lot of things to take into account.

During the meetings we had with our participant, we found out that a lot of solutions to some partial problems would cause extra problems for other muscles or parts of the leg.

The final version of this concept, which was an exoskeleton for around the knee therefore only focused on one partial problem first. Because of that, we were able to come to a better concept together with the participant. However, the participant did find some problems in this idea.

These mainly were:

Stability; If the participant were to use this product, his legs would be forced to move in a position he cannot make himself while standing. Because all of this bodyweight would still be on his legs and this position does not come natural to him, he will lose balance. This means the product would need a different component or product as an addition for it to work.
Locking of the knees; If the knees of the participant get locked in the stretched position like this, that would not necessarily help him. In case he loses balance and his legs are stretched, he can not correct himself anymore. Next to that, the muscles in his legs make him want to stretch all the time already.

Concept: horse saddle

The concept of the horse saddle was a little less complicated. The participant told us he would like the product to support (some of) his body weight. That is because this would release (some of) the pressure on his legs. After doing some ideation we came to the horse saddle concept. When we discussed this idea with our participant, he told us that his biggest concern with this idea was the stability and balance that would be needed. We then took this feedback, and created an extra support and changed the shape of the product a little bit, such that it would become less of a problem. After improving and detailing we came to the final concept of the horse saddle.

This concept was discussed in later meetings and the participant really liked this idea. He was excited to try it out. Unlike the first concept, the participant did not have any major concerns for this concept. The only thing that we had to keep in mind was the sturdiness and stability of the product.

Final choice

Comparing these concepts might be difficult since these are completely different products. However, based on their functionality, advantages and disadvantages, we were able to make a good comparison.

For the functionality the following comparison could be made:

Both concepts make it possible for the participant to stretch his leg muscles in the horse position. However, the exoskeleton would also give the participant extra knee support. After discussing this function, it turned out that this would not add much extra value to the participant. Next to that, the second concept has a function to support some of the body weight of our participant. This is something that was desired by him, because it would release some pressure on the legs. That means that based on the functionality, the horse saddle concept would be the better option.

These functions also describe the main advantages and disadvantages of both concepts. For these, a comparison could be made as well.

Looking at this table with advantages (+) and disadvantages (-), it can be seen that the horse saddle would again be the better option.

All in all, this meant that both the functionality and advantages of the horse saddle concept were better than those of the exoskeleton concept. Therefore the horse saddle concept fits the needs of the participant the best. We kept working on the idea and it was developed to our final concept.