Pictures of the final prototype

Work in progress: the final prototype

We lasered for the third time. This time we are happy with the results.

We connect the several plates together with the snap connections. We do this for the two halves.

We place the wheels in the part with the holes.

We attach the battery to the aluminum frame.

Then we put the second half on top of the first one.

These two will be fixed together with straps.

PROTOTYPE #27

We cut a little more of the tube, because it wasn't enough.

CONCLUSION:

Expected positive feedback: The ball launches in a nice curve.

Unexpected positive feedback: /

Expected negative feedback: /

Unexpected negative feedback: /

Makeabilityscore : 4

PROTOTYPE #26

We change the position of the tube, and we though that the ball lost power because the ball hits inside of the tube, so we took a piece of the ramp away so it wouldn't be in the tube as long.

CONCLUSION:

Expected positive feedback: The ball is launched in a nice curve

Unexpected positive feedback: /

Expected negative feedback: The impulse is not enough because the battery was getting low

Unexpected negative feedback: /

Makeabilityscore : 4

PROTOTYPE #25

We thought maybe we could use some tube as a ramp.

CONCLUSION:

Expected positive feedback: The ball shoots out in a high curve.

Unexpected positive feedback: /

Expected negative feedback: /

Unexpected negative feedback: The tube doesn't fit and shoots out with the power of the ball.

Makeabilityscore : 4

PROTOTYPE #24

The important point in this prototype is the ball's exit. First, we don't use any aid.

CONCLUSION:

Expected positive feedback: The ball launches

Unexpected positive feedback: /

Expected negative feedback: /

Unexpected negative feedback: The ball shoots out towards the ground and doesn't fly far

Makeabilityscore : 4

PROTOTYPE #23

After we got all our parts, we started to build our final prototype.

To test if everything works fine, we builded a test arrangement.

For our final prototype, we used:

- 2 C-profiles

- 2 wooden wheels (diam 100 mm)

- 2 gears (diam 145 mm)

- 45 mm between wheels

- 12VDC motor, 35W (heavier than previous motors)

- 1 Fader to regulate speed of wheels

- 4 copper gliding bearings

- some bolts to keep everything together

Conclusion:

Expected positive feedback: The system works and the ball shoots further.

Unexpected positive feedback: /

Expected negative feedback: /

Unexpected negative feedback: - Battery is low after 5 minutes, motor asks too many ampères and goes off quickly.

- Fader is too weak and can't resist the high ampères flowing through.

Makeabilityscore : 2 (4 hours work)

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 

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)

PROTOTYPE #16

The position of the screws is amended

CONCLUSION:

Expected positif feedback: It went a little bit further.

Unexpected positif feedback: The noise of motor is nice for the dog

Expected negatif feedback: The ball still doesn't go 15m.

Unexpected negatif feedback: /

Makeability score: 2

PROTOTYPE #15

- Visit 2 to Jana- We have added two screw to prevent that the wheels don't expel again.

CONCLUSION:

Expected positif feedback: It went a little bit further.

Unexpected positif feedback: The noise of motor is nice for the dog

Expected negatif feedback: The ball still doesn't go 15m.

Unexpected negatif feedback: The screws do contacts the wheel /

Makeability score: 2

PROTOTYPE #14

During the previous test, one of wheel was expelled, so they had to be replaced by others.

CONCLUSION:

Expected positif feedback: It went a little bit further.

Unexpected positif feedback: /

Expected negatif feedback: The ball still doesn't go 15m.

Unexpected negatif feedback: /

Makeability score: 2

PROTOTYPE #13

To make the launcher autonomous we went to buy a battery pack (12V 1,3Ah). The wheels are able to turn for about an hour. That is more than enough for this application. Jana will never go over the hour a day to throw tennis balls with her dog.
 

With this battery the wheels turns faster but the ball doesn't go much further.

CONCLUSION:
Expected positif feedback: It went a little bit further.

Unexpected positif feedback: /

Expected negatif feedback: The ball still doesn't go 15m.

Unexpected negatif feedback: One of the wheels came lose during one of the tests.

Makeability score: 2

PROTOTYPE #12

The last adaptation is the launching strip in front of the wheels, this makes the ball go higher and therefore also further. 

CONCLUSION:

Expected positive feedback:
De ball is launched.

Unexpected positive feedback:
The ball goes further then expected. 

Expected negative feedback:
The ball still doesn't go very far. 

Unexpected negative feedback:
/


Makeability score: 2

PROTOTYPE #11

To have more resistance on the wheels, we attached rubber bandages around it. The effect was not super, but the ball went further then without the bandages.
In this prototype, we also used the launching tube, wich also helped to launch the ball further.

CONCLUSION

Expected positive feedback:
De ball is launched and goes further then without tape of launch tube.

Unexpected positive feedback:
/

Expected negative feedback:
The wheels don't turn completely equal. The tube is not steady enough. It has to have a better atachment.

Unexpected negative feedback:
We expected more power.

Makeability score: 2

PROTOTYPE #10

To get more surface of the wheels touching the ball, we made thicker wheels and gave them a curve on the sides. The size of the before sanding was diam . 83 mm. If we launch the ball, we notice it doesn't go further then the small wheels. Even a bit shorter. But maybe, that's because we didn't use a launch tube. 

CONCLUSION

Expected positive feedback:
De ball is launched.

Unexpected positive feedback:
/

Expected negative feedback:
The wheels don't turn completely equal.

Unexpected negative feedback:
The ball doesn't go further then with the thicker wheels. We expected more power of it.

Makeability score: 2