Table of contents:
- The mechanics of springs and using them for propulsion(Daniel)
- Stepper Motor programming for spring loading (David)
- Simple servo program for writing degrees of rotation (David)
#1 The Mechanics of Springs, pulleys and propulsion
As it is now decided that we are going to use springs for our propulsion, I belive that some elaboration is in need.
The plan is to use a pully system, made up of 3d printed parts to pull back 4 compression springs(specifically 65mm x 6.8mm, 0.11N/mm), to then release the built up force to propel the projectile in the barrel.
The force you get out of a spring is calculated by the formula for stored potential energy in springs :
As we have 4 springs the only change is that the K factor will be multiplied by 4.
I am working on developing a pulley system for the spring tensioning.
For those of you who do not know, a pulley is a system that reduces force needed by redirecting the work into multiple axis of load.
There are many different types of pulleys, which all disperses the load in different ways.
The most prominent systems are; fixed pulley, movable pulley and block and tackle.
Destin Sandlin from “smarter every day” of Youtube has a beautiful video on how the work. I found a new appreciation for applied physics with this video, you can watch it down below if you to are extra curious.
#2 Stepper motor for spring loading
We figured a way of loading the spring would be to use stepper motors. The advantage of a stepper motor is that we have some options in terms of how many “steps” we can set. The main objectives of its function are;
-Load the spring from top to desired firing strength.
-If the stepper motor arrives at the last spot on the spring loading step, it should stop and initiate a reset after firing.
What remains to be done is a reset mechanism, which is harder than it might appear. There needs to be some communication between the firing mechanism and the reset mechanism. To reset the spring loading prematurely ruins the firing mechanism. So, while work is being done there the program will have to wait.
#3 Servo motor for turning in x-axis:
