Pneumatics

Air Pressure Controlled Movement

With Pneumatics we can make linear motion using air pressure and software controlled valves. The VEX system provides for single acting and double acting pistons. A single acting gives a push with air pressure, while the double acting can give a push or pull force with air. Mostly we use double acting, if we need only single we just use one side of the double acting.

2023 New Product

A new system was released in 2023

Old Pneumatics system

the old system components are still in use and described below. The details below are still a good reference for how to use pneumatic systems in general.

VEX legal parts list

Pneumatics Instructions

How to assemble and use the components of the VEX pneumatics system are shown in this Document.

The document gives detailed descriptions of each part and how to assemble them. If this is you first experience with pneumatics you must read this Document.

Pneumatic Device Set Up

Code for Pneumatics

The code for the VEX pneumatics is basically telling the solenoid valve to switch from one position to another. This is done with a digital signal through the 3 wire ports of the V5 Brain. The method we use is

digital_out.set(bool)

Where bool is either true or false. True will send the air one way, false will send it the other.

in main.cpp these lines can now be written in any function to control the pneumatics.

  Pneu1.set(true);
  wait(1000, msec);
  Pneu1.set(false);
  wait(1000, msec);
  Pneu1.set(true);

This code will just move the pneumatic cylinder from one position to the other after waiting a second between moves.

Another method available for Pneumatics is to determine what the solenoid is set at:

Pneu1.value();

will return true or false depending on what was the last set of the solenoid. We can use this to create a toggle function for the pneumatic solenoid valve.

Pneu1.set(!Pneu1.value());

Will set the solenoid to the opposite of where it is now.

Driver Control

Here is a user control code that will let you move a pneumatic based on pushing buttons A or B

void driverControl() {
  while (true) {
    if (Controller1.ButtonA.pressing()) {
      Pneu1.set(true);
    } else if (Controller1.ButtonB.pressing()) {
      Pneu1.set(false);
    }
  }
}

Function

Using a function will organize your code better and make it easier to debug any problems. To write a function we need a type, a name, a list of arguments and some code conetained in curly braces.

void pushPneu1(bool push)
{
  Pneu1.set(push);
}

This is our function. It just sets the Pneumatic to true or false based on the argument that we send it when we call the function. Next is how to call the function from driver control. This code will set the pneumatic when we push buttonA. or send it the other way when we push buttonB

void driver() {
  // User control code here, inside the loop
 
  while (true) {

    //use ButtonA and ButtonB to activate the Pneumatic 1
    if(Controller1.ButtonA.pressing())
    {
     
      pushPneu1(true);
    }
    else if(Controller1.ButtonB.pressing())
    {
      pushPneu1(false);
    }
    wait(10, msec); // Sleep the task for a short amount of time to
                    // prevent wasted resources.
  }
}

 

You can also call this function while in auton mode.