First project - Fetch and Treat Machine for Dogs!

Using Arduino Project Guidance
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Hi!

So I have 0 experience with arduino and electronics in general, but always interested in technology and I have some background in programming and 3D (If custom 3D parts need to be printed) so hopefully that helps.

As the title says, I want to make an automated ball throwing machine for my dog that also dispenses a treat. But I have no clue where to start, what products to use, what pitfalls there are,...

I chose arduino because of (hopefully) the relative ease to program the different components and tune them in on eachother.
My main questions are:
What are effective parts I can use?
Can they all be conected to the same arduino?
what about power source?
Can I optimize or simplify?

here is an example project a guy did, very close to what I want to achieve.

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[Album] Automatic tennis ball launcher - Album on Imgur

So I made a beautiful sketch heavely based on the project mentioned above.
1: Ball and ball collector
2: some kind of switch/sensor (micro switch?) to detect when a ball is provided
3: a selonoid that pulls back a pin to let the ball pass (when te DC motors are spinning and treat is dispensed)
4: two DC motors that spin to propell the ball (a range of 2-5m would be enough)
5: a servo that can slightly point the machine to a different direction to randomize the ball location
6: a servo with a panel attached with a hole that can rotate and pass a treat from the dispenser before it rotates back to block the other treats

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I have no clue if this can all be attached to one arduino and I have no clue how this all should be powered?
I don't know what kind of wires and other small pieces I need to make it all connect and work?
let's say this is my basic list of items for now:

2 DC motors to propell the ball
(TT motor, 3V/6V, 180mA/250mA, 45 ± 10% r / min 90 ± 10% r / min DC motor

1 Selonoid to let the ball pass the tube when it's detected and the DC motors are spinning
(12VDC, 250mA, 5,5m push pull, DC coil 40ohms, 5Newton) Selonoid

switch to detect when the ball is inserted (max 30mohm, 5A/125Vac, 3A/250VAC) micro switch

and to top it off, a kit with all basic beginner stuff arduino kit

And the arduino itself! Arduino

hopefully you guys can protect me from rookie mistakes and give some awesome advice :slight_smile:

1 Like
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If everything goes well, this doggo will be gratefull!
(and I will hopefully have a good base knowledge for future projects :wink: )

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Ok so I also posted this on another forum and some guy already helped me a bit, i'll give a quick summary:

The DC motors will be too weak and i'll need a 12V motor
So I searched the internet and found this: (might be a bit sketchy looking at the price)
Machifit-25GA370-DC-612V-130rpm-Gear-Reduction-Motor-with-Mounting-Bracket-and-Wheel
and this one might work as well (compared to other DC motors this is also dirt cheap, a catch?)
775-Gear-Motor-DC-12V-36V-3500-9000RPM-Motor-Large-Torque-High-power-Motor

So he also told me i'd probably need relais (to turn on/off) or transistor or mosfet.
Not sure what the difference is yet ^^
And motor drivers?? no clue what it does except maybe sync wheels or something?

And the starter kit is way more than I need but I figure it might be fun to have it for other projects.
Also the selonoid might be a bit short, but I think it will manage if the pipes are tight enough

My further questions were:
I assume all these motors etc need a bunch of power and batteries won't do the job...
So I found a 19V laptop charger, don't know if this could be usefull to power everything?

Do I need some stuff to regulate all the different voltages of the different elements so it doesn't blow up?(selonoid 12V, DC motor 6-12V, servo 5V, micro switch...)
If so what do I need and what does it do :o

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One thing that bothers me about the design is that apparently the ball goes back into the same place that it comes out of. That suggests a risk, especially if there is more than one ball around, of the dog getting smacked in the head as it delivers a ball. Even if there is only one, the dog may stick it's head in there wondering where the ball has got to.

I would prefer a more complex mechanical arrangement where the ball is fired from one place and returned to another.

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Ah i'm sorry that this isn't clear!
The bal goes in on top and goes out at the bottom :slight_smile:
So it goes in the funnel at nr 2 and it flies out at nr 5

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eliasleo11:
Ah i'm sorry that this isn't clear!
The bal goes in on top and goes out at the bottom :slight_smile:
So it goes in the funnel at nr 2 and it flies out at nr 5

Oops, it is clear from your diagram, not so much from the picture of the other guy's hardware.

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So more info:

my shopping list for now:
2 DC motor 12-36V

1 selonoid valve 12V
https://nl.banggood.com/Excellway-DC-12V-5N10mm-Push-Pull-Open-Frame-Mini-Valve-Solenoid-Valve-Actuator-Electromagnet-p-1097540.html?akmClientCountry=BE&rmmds=cart_middle_products&cur_warehouse=CN
Switch

and the kit

So I assume I need mosfet for the magnetic valve (push pull controll) and 2 for the DC motors (turn on off and controll speed)

And I need a step down regulator to get the correct voltage to my DC motors so they run correctly on the voltage provided?

And another stupid question, but my old laptop charcher (19V output) could it suply the entire system of power? (when all my different element are under 19V each?)

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Great project! I'm not clear if you are building this or the dog is :confused:

I have no comment on the motor, solenoid and switch look OK.

Starter kit looks good for leaning about Arduino and micro-controllers in general.

MOSFETs you list are no good, you need logic level MOSFETs. Typically logic level MOSFETs have an 'L' in the part number. If they are not logic level they probably won't fully turn on with the 5V from the Arduino, and just to make you feel better, I have fallen into this trap and I should know better. Lots to chose from, IRL530 for example.

You also need a diode across each motor and the solenoid, connected so it is normally reverse biased (cathode to +ve), the diode is to absorb the back EMF that happens with any magnetic device when the power is interrupted. Diode should have an If of at least the maximum current drawn by the device it is across.

Not essential but it also helps to put a 0μ1 capacitor across each motor as close to the motor as physically possible, to reduce electrical noise.

Laptop charger should be fine.

One final thought, does this really need any kind of controller? Spin the motors, drop a ball in, press a button to operate the release solenoid.

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Also asked here (in Dutch): Het Nederlandstalig Arduino forum - Bekijk onderwerp - Eerste project - Fetch & treat machine Honden.

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PerryBebbington:
Great project! I'm not clear if you are building this or the dog is :confused:

I have no comment on the motor, solenoid and switch look OK.

Starter kit looks good for leaning about Arduino and micro-controllers in general.

MOSFETs you list are no good, you need logic level MOSFETs. Typically logic level MOSFETs have an 'L' in the part number. If they are not logic level they probably won't fully turn on with the 5V from the Arduino, and just to make you feel better, I have fallen into this trap and I should know better. Lots to chose from, IRL530 for example.

You also need a diode across each motor and the solenoid, connected so it is normally reverse biased (cathode to +ve), the diode is to absorb the back EMF that happens with any magnetic device when the power is interrupted. Diode should have an If of at least the maximum current drawn by the device it is across.

Not essential but it also helps to put a 0μ1 capacitor across each motor as close to the motor as physically possible, to reduce electrical noise.

Laptop charger should be fine.

One final thought, does this really need any kind of controller? Spin the motors, drop a ball in, press a button to operate the release solenoid.

allright lots of good stuff!
And nope, sadly my dog is even worse at building stuff than I am ^^
No it doesn't really need any controlls, it just basically needs to work when it's plugged in :slight_smile:

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Koepel:
Also asked here (in Dutch): Het Nederlandstalig Arduino forum - Bekijk onderwerp - Eerste project - Fetch & treat machine Honden.

Yes I'll be keeping both topics up to date for the english/dutch speaking people :slight_smile: