I would like to build a model that releases table tennis balls down a track at a certain number per minute by opening a gate or turning a motor (with an attached wheel with cutouts for the balls to roll through)
I would like to be able to have multiple gates set to different release rates, and be able to change the release rates easily on each gate.
Arduino seems like a great way to solve this problem, but the issue is, I am a complete novice! I was considering buying the Arduino Engineering Kit Rev2 and figuring out and then ordering the bits I need to build my model.
Any insight on the best way of getting myself up to speed with what I need to know to build this with Arduino would be appreciated!
Hopefully you do not need this tomorrow. I suggest before purchasing anything get a copy of the Arduino Cookbook and skim it cover to cover. Then spend time on the area pertrent to your project. Put together a simple annotated schematic and post here we will be very happy to review it and pass on any knowledge we can. While you are waiting on the "recipe book" follow some of the online tutorials, some are good some are bad so do ot take them as being all correct.
I feel the Kit is more than what you need for this project.
To help you define your materiel needs, try putting your words into a simple drawing, then refining your drawing. For example, I can imagine a hopper of table tennis balls, funneled to a servo arm that lifts and lowers slightly to release one ball... missing parts to the drawing begin with: "funnel", power supply, Arduino, connecting wires. To make the release rate adjustable, I would add a "start" button or switch, an "up/down" adjustment (knob, two buttons, joystick). If I want to know the exact rate of release, a display (LEDs, 7-segment LED, OLED, NeoPixel, TFT).
I have no experience of Computer programming, but have worked with 5 axis CNCs, so have quite a bit of experience of writing CNC programs.
I have very basic electronics experience, but have wired up my campervan if that helps?!
Basically, I am starting pretty much from scratch, but am a quick learner and have some practical experince of model building, just not the electrics bit.
Each gate could be a short rod controlled by a servo. Gate 2 should be stronger.
For this particular approach you need a suitable power supply, your Arduino, a couple of servos and a a way to tell the program what rate you want, and to know what rate is set at the moment. This latter part can be achieved using a pot, a rotary switch, a couple of buttons, a display, or touch screen, you name it.
My point is that you first have to come up with a physical design or even a (manual) prototype, and then start thinking on the mechanical actuators (motors, sensor, switches, ...), and finally start programming. Questions will arise, such as how long to wait on steps 2 and 5? Is this a timed wait, or triggered by sensors? What happens when no more balls are left? ...
As xfpd said above, I think I would just use a servo arm and figure out the best timing with experimentation. The balls would be running in a v groove, careful spacing should mean that when downstream is full the servo will try an release a ball but it will not have far enough to travel and the servo arm will push it back slightly on close.
Hi @notyetbarrelled - I think @mancera1979 idea of two release mechanisms (two servos) is very good. One servo releases the first ball while the other servo holds back the rest of the balls.
How would you know if a servo was “strong” enough to hold back 10 balls? Possibly a straight actuator would be a better choice for the multi ball holder and a servo for the single ball release?
It is important that the gates release an exact number of balls in a know time (probs 10 seconds). My goal is to demonstrate a bottleneck in a production line (your slowest process always dictates output of entire system). That way I can run it for 50 secs for example to demonstrate 5 working days or alternatively I could run just one cycle at a time.
I think you are right that I have more planning to do before building. I guess I would like an idea on how much knowledge of programming it is going to take for me to be able to do it!
If I need to study programming for 6 months, it is probably a bit too much work and I might need to do a more low fi solution on a physical crank instead!
Trial and error... so anything you can imagine will do. I imagine these servos moving like a toll booth, first servo releases a ball, then closes, then the second servo releases all the balls to move forward, but because of spacing, the "second" ball is perfectly positioned. The servos are only holding the "top" of the ball, using minimum of movement (zero-to-ten degree movement rather than zero-to-ninety degree) to release the balls. The issue of jamming the hopper is real (if rice can jam in a bottle neck, so can balls). Maybe an off-balance DC motor to shake the neck of the funnel? Run with it. You can not go wrong.
No. (but I may be outnumbered here) I feel that if you have the spacial ability to imagine these things, find similar projects, keeping it simple, ask questions. You will do well.
Here is a simulation from wokwi with human input of one servo. Look at the code. Not too lengthy.
Here is another simulation from wokwi that is slightly more complex:
Most of the complexity is formatting the output for reading.
I have made a good start on the project (as attached).
This is dependent on the momentum of rolling table tennis balls not damaging/halting the movement of small servos. (I will need to experiment with the angle of slope and timing of gates).
Also, can you run 5 servos from the 5v source on the Arduino? Will the usb connection provide enough power or do I need to buy a power supply plug?
It is not the most elegant fix probably, but will hopefully work!
Save yourself some heartache and don't run even one servo off the Arduino supply. Add a separate supply for the servos. How many servos do you anticipate may be running simultaneously?
There will be a minimum of 5 servos, but not running simultaneously........yet.
What does an external power supply look like for something like that? I have very limited electrical experience so would hope it was a simple solution to provide power from an external source?
A wall wart is about as simple as it gets. Check the current capacity of your selection. Cut the connector off and connect to a shield like @paulpaulson pictured. Be mindful of your polarity!
