ATTACHMENT SYSTEM

The system to attach the tennisball thrower to the wheelchair/table.

We believe in a system with bolts (1) that would be on both sides of the product and a support bolted to the seat (2)

When the product is not used. 

We've thought of a more ergonomic and easier system for Jana to store because she can not lift her arms to great heights. 

It is bolted to the a T-slot onto the table. As shown in the example.

When the product is used.

SELECTION MATRIX

PROTOTYPE #22

In this prototype we made a variation of the previous catapult. In this catapult Jana should be able to wind the catapult herself.
The mechanism works but the ball doesn't fly more then 40 cm.

Conclusion:

Expected positive feedback: The system works and the ball lounches.

Unexpected positive feedback: /

Expected negative feedback: The ball doesn't fly far.

Unexpected negative feedback: The ball sometimes falls out of the holder.

Makeabilityscore : 4

PROTOTYPE #21

In this prototype, we made a general catapult. By using 2 big elastics, the ball gets a good speed to fly away for about 5 metres.

The catapult gets tension by the dog pulling the cord untill it fits after the hook. If that is done, the ball is ready to be launched anytime Jana wants by pushing the cord up. (which is very easy to do)

By moving the wheelchair up and down, it's possible to aim. 

Getting ready:

Launching: 

CONCLUSION:

Expected positive feedback: Easy to launch once it has tension. 

Unexpected positif feedback: Less dangerous than we thought. Shoots quite good.  

Expected negatif feedback: It's a position that's not very reachable for Jana.

Shoots not that far as necessary. With this system, it's impossible to change the shoot range.

Unexpected negatif feedback: /

Makeability score: 4 

SPRING

We bought a toy for use the spring that this had, for we could do prototypes, at the time of testing the toy, we realized that this provided a new idea which we had not worked, that was the convination of the spring and the tube sucking the air, an interesting idea.

CONCLUSION:

Expected positive feedback: Fly about 15 meters.

Unexpected positive feedback: It's a good combination. 

Expected negative feedback: It's needed much force for Jana this mechanism is not good

Unexpected negative feedback: /

We perform different ideas for a prototype, we want to use elastic spring like mechanism principal, these are some of the ideas realized.

 

Sketches 1

Sketches 2

PROTOTYPE #20

Another variotion on protypes #18 and prototype #19.
We attached the elastic again around the tyre + we folded the end of the tyre over for extra stifness to create more pressure.

By launching it, we achieved a distance of 8m, which is quite good!

CONCLUSION:

Expected positif feedback: More pressure was created using the elastic + folding.

Unexpected positif feedback: Shoots remarkably further than the previous version.

Expected negatif feedback: /

Unexpected negatif feedback: The tyre seems to blow up when inflated till the shooting pressure.

Makeability score: 4 (15 minutes)

PROTOTYPE #19

Variation on prototype #18:
Because the tyre didn't create enough tension to build up the air pressure, we tried to improve it with an elastic around the tyre.

By launching it, we achieved a distance of 4m.

CONCLUSION:

Expected positif feedback: More pressure was created using the elastic.

Unexpected positif feedback: Shoots remarkably further than the previous version.

Expected negatif feedback: /

Unexpected negatif feedback: Shoots not as far as we wanted it.

Makeability score: 5 (15 minutes)

PROTOTYPE #18

Next protype is also by using compressed air. We used and old motorbike tyre (Ø60mm) to launch the tennisball (Ø67mm). We used the tension between the flexible tyre and the tennis ball to build up the air pressure.

The tension, created by the Δ 7mm, was not large enough to build up the air pressure to launch the ball properly.

CONCLUSION:

Expected positif feedback: Some air pressure was created.

Unexpected positif feedback: /

Expected negatif feedback: /

Unexpected negatif feedback: Not enough tension to launch the ball properly

Makeability score: 4 (15 minutes)

PROTOTYPE #17

Today we made some prototypes with the method of compressed air.

First prototype is a catapult, made by using a pneumatic cilinder.

The arm was about 40 cm long, with the 20cm in between the center of attachment of the cilinder and the attachment of the arm. The pen of the cilinder was placed in an angle of 90° against the arm in order to prevent it from skipping away when pushed. For the ball holder, we used a graffiti spray cap.

By attaching our compressor and shooting, we became a distance of 4m50.
To achieve larger distances you need to make the arm longer, which makes the hole structure very large.
Also the fact you need a compressor is not that handy to make it compact/portable for the wheelchair.

CONCLUSION:

Expected positif feedback: It launches the ball

Unexpected positif feedback: /

Expected negatif feedback: /

Unexpected negatif feedback: The ball still doesn't go that far.

Makeability score: 4 (30 minutes)