Production manual for the final product

This slideshow below is a manual showing how to make the scale.

Montage weegschaal2011

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Final product

Here are some pictures of the final product:

Final prototype: internal structure update

In the initial sketches of the final prototype, the internal frame consisted of a lot of parts and different materials: wooden strips, aluminium strip, steel band, screws. To simplify the product, these parts were replaced by one piece of wood.

Final prototype: drawing + dimensions

The images below show the dimensions of the scale and a top view. The hinges are big because this indicates the function of the hinges. In the drawing there is a small (green) color accent. To match the color with the personal taste of Henk, we asked him his color of choice. The colors that Henk prefers for the hinges are dark orange or black.

Final Prototype exploded view

The sketch below is an exploded view of the final prototype.


Parts:
1) Plexiglas with black paint on the back
2) Aluminium strip
3) Wooden frame
4) Aluminium hinges
5) Aluminium profiles
6) Rubber strips
7) Sensors

Prototype 7

Prototype 6

Idea: Rope

This idea consists of a rope and a balance on the upper part of the rope. The idea is that Henk can climb the rope and see his weight. The advantage is that the system is very compact. This idea is not possible for Henk because of two reasons:


- The muscles under his waste are not enough developed to support the weight of his legs. This could injure the muscles.


- It's very difficult to 'land' back in the wheelchair. When the rope is above the wheelchair, Henk would land with his feet in the chair. When the rope is in front of the wheelchair, Henk would land in front of the wheelchair.

Prototype 5

Prototype 5 is a plate to place under the front legs. There is also a small strip to put under the back legs. There is also a button to put the display back on.

Prototype 4

Prototype 4 is a plate that can be rolled in one direction, when it's rolled out it's stiff in the other direction. When rolled out, the scale has the shape of a plate. This can be used with both wheelchairs and normal chairs.

Prototype 3

Prototype 2

Prototype 1

Scale

We found a cheap scale in a 'Blokker' store. There are 4 seperate pressure sensors in it. These can be used to put under the legs of a chair.

First Ideas

These are the first ideas for the weighing mechanism:


Idea 1: 
This idea consists of presure points that can be placed under the legs of a chair. 

Idea 2:
This system can only be used on a chair with one leg. The advantage is that there's only one pressure sensor needed and there are less cables (less messy).

Idea 3:
This idea is basically some sort of add-on to use with a regular scale and a chair. The disadvantage of this system is that the display is not well readable. 

Idea 4:
This idea uses plastic tubes filled with water. The weight of the person causes pressure in the tubes. One can read the weight on the height of the water surface.

Idea 5:
This idea uses the system of a traditional scale with springs. (mechanical scale)

Meeting with Henk 1: What are the problems

During the first meeting with Henk, we discussed the most important problems that he encounters if he has to weigh himself.


Problems:


- With a normal scale, Henk has to sit on the scale and try to balance. This is very difficult because he doesn't have stability in the lower part of his spine. He also has to grab his legs and while doing this he has to manage to read the little display. All these thing together make it a nearly impossible task to weigh himself.


- The scales that are designed to use with a wheelchair are very large, heavy and bulky. They are also expensive and are not designed for usage at home. 

- The scales that are designed for wheelchairs use a big plate onto which the wheelchair user has to drive. The wheelchair has a weight too, so in order to determine the weight of the wheelchair, the wheelchair user has to get out of the wheelchair, weigh the the wheelchair and get back into the wheelchair to determine his own weight. 


Possible solution:


- For Henk it's easy to switch between a wheelchair and a normal chair. So a possible solution is to design a scale with separate pressure sensors that can be placed under the legs of a chair. It's also important that the display is placed on a location where it's readable. Another important aspect is that the scale has to be as compact as possible so the scale can be put away. The scale also needs a 'zero button' to cancel the weight of the chair.

Rapport ergotherapiestudenten

D4E1_rapport_henk

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