Arduino Mechanism For Firing Object

Projects General Guidance
1

Hello,

I am currently working on my first project, where I will be making a distance-measuring turret, that can fire a ball at a certain speed at a target.

But, the problem I have is, that I don't know which mechanism to use for firing the object.

What I am looking for in the mechanism:

*It should be compact

*I should be able to choosing the power at which, the mechanism unloads upon the projectile. So that I deliver the same amount of force to the target regardless of distance. I.e, it doesn't only fire at one speed.

*Reload automatically. I.e not human interference between each winding/loading of power. The actual automatic-ammunition-loading I will incorporate myself :slight_smile:

What I have though of myself, so far:

A barrel, much like a gun with a spring inside. The coil will be attached to the end of a servo which is situated horizontally, which in turn is attached to a wheel, that is driven forwards/backwards by a DC motor. The servo will act as the latch mechanism, so that when It goes from 180 to 90-ish degrees the coil will drive the projectile forwards.

Of course, I don't know if this sort of setup will be able to reach the highest velocity compared to say, a crossbow mechanism with a string.

Also, if any of you have any links to guides to choosing coils, I would very much appreciate that :slight_smile:

2

Look into how airsoft works not sure how big your ball is but bigger the ball more power and harder it will be.

3

PVC tube + pressurized air?

4

zwieblum:
PVC tube + pressurized air?

I don't have much experience with this, but isn't it very much an on/off thing? Either it shoots or it doesn't, but when it shoots it will shoot at the same speed? Also, wouldn't this be quite expensive in the long run?

wolframore:
Look into how airsoft works not sure how big your ball is but bigger the ball more power and harder it will be.

Surely this would be the best option, but wouldn't it be a bit too advanced? I am still quite new at this in regards to electrical engineering and programming, I have absolutely zero experience in mechanical engineering.

5

Part of the fun of this hobby is figuring it out. Explore it while and work it out unless you have a better idea.

6

wolframore:
Part of the fun of this hobby is figuring it out. Explore it while and work it out unless you have a better idea.

Well, that is a point. I also planned on testing it, after you mentioned it. Or atleast a bastardized version of an airsoft mechanism.

Thank you, for the suggestion.

7

You could also explore flywheels similar to a baseball shooter

8

It matters a lot whether this ball is a BB or a basketball... It also matters how fast you want to shoot those balls, in terms of both barrel speed and shots per time.

Do start by narrowing down your requirements.

9

wvmarle:
It matters a lot whether this ball is a BB or a basketball... It also matters how fast you want to shoot those balls, in terms of both barrel speed and shots per time.

Do start by narrowing down your requirements.

Well, I understand that. I haven't completely decided on the size of the ball/projectile.

Do you perhaps have any words/terms I can look up on in terms of the physics for this project?

I tried searching for spring velocity and the like, but nothing came up on the Google. I would like to learn this part aswell :slight_smile:

10

it's basically a parabola. with some math you can figure it out using the following parameters:

velocity, mass, angle, gravity and time.

search projectile motion

11

Hyperphysics

http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

Actual made since long ago Spring Guns use the spring to push a piston to compress air....

With propane and a combustion chamber you wouldn't need a compressor but perhaps would need a permit.

Carbide/acetylene would be an even bigger accident waiting to happen.

12

I am currently working on my first project, where I will be making a distance-measuring turret, that can fire a ball at a certain speed at a target.

What will the Arduino do? You will want to work through at least some of the provided examples to get an idea of its capabilities.

13

aim? blink lights? just be cool?

14

wolframore:
it's basically a parabola. with some math you can figure it out using the following parameters:

velocity, mass, angle, gravity and time.

search projectile motion

Search words: Newton's Laws of Motion

Shoot tennis balls and learn about drag.

But with Arduino you don't need to calculate especially if you want speed. You table your inclination and power values by range and look them up by range. The table goes into flash/PROGMEM, not RAM.

15

wait I want an Arduino on my gun!

16

For launching projectiles I can think of several mechanisms.

Catapult/spring (needs a mechanism to pull back the spring, and something to release it).
Swing arm (as used for clay pigeons).
Compressed air (potato gun).
A pair of fast running wheels (used to launch tennis balls, rugby balls, etc - typical larger stuff).

There are probably more mechanisms. It all depends on what size/weight of ball you want to shoot, how far, etc.

17

How hard or soft should the projectile be? Shape/diameter/weight?

Should it be people-safe?

18

What’s the fun in that.. :smiley:

19

wolframore:
wait I want an Arduino on my gun!

Hahah, good to see I have inspired someone!

GoForSmoke:
How hard or soft should the projectile be? Shape/diameter/weight?

Should it be people-safe?

Well, I don't think it would be very safe for the prototype NOT to be persons-safe.

But, I am thinking of using 4,5mm pellets for an airgun.

20

jremington:
What will the Arduino do? You will want to work through at least some of the provided examples to get an idea of its capabilities.

Well in a bit of detail, what I plan to make:

  1. Turret Base

I am thinking of making a base akin to spherical security-camera, with servos for tilting and panning.

Of course, I will need some sort of feedback mechanism for the servos to tilt all 360 degrees.

  1. Distancing

The distance will be measured by a simple HC-SR04 supersonic distance measurer.

I will need to calculate an algorithm that will feed into the DC-motor for the spring. I will elaborate on that more in the next point.

  1. Targeting

At first, I will have to manually with a joystick tilt/pan it up/down.

Next stage, I plan for the HC-SR04 to rotate on top of the turret via a servo. This HC-SR04 will feedback to my computer with an interactive SONAR-map, where I can press on the objects and it should aim at that degree.

And final stage, it will do the previous stage, but with a camera mounted on top to spot a specific animal. It will then send me a message, so that I can decide whether or not, if it is indeed that animal, so that I can shoot a pellet at it and scare it away.

  1. Firing mechanism

I have decided on a spring in the back of a barrel with a plastic object in front of it. The plastic object will have "cog-hooks" mounted to the bottom of it, which go with a cog, that will be driven by a DC motor.

What I am looking for, is help with calculating the algorithm, so that the DC motor knows how far to turn back, before shoot the pellet at a certain distance with a certain force.

OBS. Of course, all the later stages are technically irrelevant at this point. Just wanted to paint a whole picture.