INSTRUCTABLE

link to the instructable of our product:

http://www.instructables.com/id/Detachable-ball-launcher/

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

CASE

First we decided to make the case, using a vacuum forming process. This because it's relative easy and cheap at school. Nevertheless these advantages it's not the best solution for our case because the accuracy isn't that good; this resulted in a gap inbetween the two halves.

After the photo session of our product we had the feedback to use another process to form our case to become a good finish of the case. A suggested method was using the lasercutter.

Finally we decide to go for a lasercutted ABS case (with the experience we have to bend materials using the lasercutter, we'll try to make a nice case in this way). These are the illustrator drafts for the lasercutter:

To do list

- case (laser)

- instructable

- ramp

- attach system

- movie

Exploded view

Presstext

Jana is een enthousiaste jonge vrouw die afhankelijk is van haar trouwe viervoeter. Omdat haar hond haar overal begeleidt, zou Jana haar graag belonen voor het geleverde werk. Ze zou dit graag doen door tennisballetjes te smijten, beter gekend als het klassieke "à porte".

Dit wordt echter bemoeilijkt door het feit dat Jana een beperkte spierfunctie heeft, waardoor het voor haar onmogelijk is om een bal voorwaarts -en vooral- ver weg te gooien. Deze gebreken staan dus een speelse interactie tussen Jana en haar viervoeter in de weg.

Het idee dat wij hebben uitgewerkt is geïnspireerd op een professionele base-/tennisbalwerper. Bij dit systeem worden er twee wielen aan het draaien gebracht met behulp van één elektromotor en een tandwieloverbrenging. De tennisbal wordt vervolgens doorheen deze wielen geperst en versneld; de tennisbal vliegt enkele meters door de lucht.

Aangezien Jana in een rolstoel zit, moet ons ontwerp hieraan aangepast zijn: een makkelijke aan- en afname is wenselijk. Een extra eis is ook om -met wat marge- doorheen deurgaten te kunnen manoeuvreren.

De uiteindelijke tennisbalwerper voldoet aan al deze eisen en kan de bal een 15-tal meter ver schieten. Zowel Jana als haar hond zijn unaniem enthousiast!

Jana is an enthusiastic young women who depends on her dog. Because her dog accompanies and helps her all the time, Jana would like to reward her for the work she does. She’d like to do this by throwing tennis balls, also known as the classic “fetch”.

But this isn’t an easy task for Jana because she has a limited muscle function, because of this she isn’t able to throw a ball far or even forward. Because of these limitations it’s harder to have a playful interaction with dog.

The idea that we developed is inspired on a professional baseball/tennis ball thrower. In this system there are two wheels which are made to spin by one electromotor and two gears. The tennis ball is then pushed through these wheels and accelerated; the ball is then airborne for several meters.

Since Jana is in a wheelchair, she has to be able to attatch and detach the launcher in an easy way. An extra demand is that she should be able to pass through doors easily.

The final tennis ball launcher meets all these requirements and is able to launch a ball 15 meters far. Both Jana and her dog are unanimously enthusiastic!

Group picture

Visit 4 to Jana

The previous attachment system did work but the result was too wide. Jana couldn't ride trough the door. So we tought about another solution. We came to a system where the machine is suspended from the armrest.
We do this by attatchin a alluminium loop on top of the machine and because a part of the machine is under the armrest we gain a few centimeters.

In the final prototype we'd like to attatch a screw at the top so Jana can fixate the machine.

To detach the machine Jana first has to loosen the screw and then by lowering her wheelchair on the same system that was used in the previous test.

We also tested if she was able to drive through a door.

We also tested the latest version of the machine itself. Jana aswell as her dog were happy with the result.

DIMENSIONS CASE

Today we decided our final dimensions after Jana's visit.
The case will be divided in two halves: one for the wheels and gears, one for the motor, battery and other electrical components...

Dimensions:

We will form a mold in PU foam and vacuum form it in PS (white, 2 mm thick to have a sturdy case)

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)

Visit 3 to Jana

We tested the attachment system with a rough prototype that presents the size. The system defenitly works, we will only need to attach the final device on the right height to go under and over it with the wheelchair. 

The bolts in the prototype are not the right size yet, that's why the prototype is hanging so loose, hat problem will be solved in the final product. 

DIMENSIONS WHEELCHAIR

Our client Jana, momently has a Permobil C300 to learn how to ride it in awaiting of her Permobil C500 Lowrider. This wheelchair has a similar wheel base and attachment rail, so we decided to design our product for this wheelchair.

We took some measures to see how large our tennisball thrower can be.
The Permobil can move vertically about 13,5 cm, so we can use this for the attachment system.

We also measured the door width and the width of the wheelchair to see how wide we can go so Jana can still pass with the tennisball thrower attached.

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