Step One: Print the Enclosure
Step Two: Set Your Servo to Neutral
Step Three: Hot Glue the Springs
Step Four: Install Servo Horn with Screws and Attach Wire
Step Five: Mount Servo and Attach Wires to Rib Plate
Step Six: Screw on the Face Plate

Published January 31, 2024

Breathing Mechanism for Animatronic Puppets & Companion Bots

Simulate realistic breathing inside your puppet or animatronic companion bot.

IntermediateFull instructions provided4 hours659

Breathing Mechanism for Animatronic Puppets & Companion Bots

Things used in this project

Hardware components

MG90S Servo

Arduino UNO

M1.2 x 4mm Screws

M2 x 10mm Screws

6 x 15 mm 2.3lb Springs

24 guage craft wire

Jumper wires (generic)

hot glue

Software apps and online services

Arduino IDE

Hand tools and fabrication machines

Hot glue gun (generic)

Story

Important:This project assumes you already know how to upload a sketch to an Arduino Uno.

I'm building a companion bot (related projects: Animatronic Fox Head) and wanted to add some movement to the body as well to help it feel more life like. I decided on a breathing motion and designed this 3D printable enclosure that uses springs and a MG90S servo controlled by an Arduino Uno with a servo easing program in Arduino CC.

Step One: Print the Enclosure

I did 4 outer shells and 20% infill to help ensure the enclosure would not be prone to bending over time.

Step Two: Set Your Servo to Neutral

Plug in your servo to the Arduino Uno and upload the Servo Neutral sketch. This sets your servo to 90 degree neutral position.

Step Three: Hot Glue the Springs

Hot glue the springs into the holes on the inner piece then into the holes on the outer rib piece. repeat on the other side.

Step Four: Install Servo Horn with Screws and Attach Wire

First screw in the M1.2 to the third hole on the inside of your long symmetrical horn that came with your servo, then attach it to your servo. Cut a length of 24 gauge wire that's long enough to be folded in half and have the ends reach the outside of the very outer edge of your assembly.

Twist wire around the tiny screws you installed on the server horn making sure they they can't slip off the screw head but they should still be loose enough to rate freely around the screw.

Step Five: Mount Servo and Attach Wires to Rib Plate

Mount the servo to the inner assembly using M2 x 6mm screws. Thread the wires through the two holes on the inner assembly and the through the rib plate holes. Making sure not to compress the springs, twist the wires tightly and then tuck the excess inside the rib plate hole.

Step Six: Screw on the Face Plate

Using M2 x 10mm screws, attach the top faceplate.

Step Seven: Upload the Servo Breathing Easing Sketch

Plug your servo into your Arduino Uno and upload the Servo Breathing Easing sketch. You can adjust the speed of the breathing with increasing or decreasing the second number in this part of the sketch:

breathe.easeTo(145, 55); //angle moved to and blocking aka time for arrival to the angle, lower the blocking number the slower the servo moves

breathe.easeTo(90, 55); //sets servo back to neutral position

Schematics

Code

#include <Servo.h>

//Created by Smalls on January 1 2024

Servo right; //create servo object to control a servo
Servo left; //create servo object to control a servo
Servo center; //create servo object to control a servo
// twelve servo objects can be created on most boards
     
void setup() {
  right.attach(9); //attaches the servo on pin 9 to the servo object
  left.attach(10); //attaches the servo on pin 9 to the servo object
  center.attach(11); //attaches the servo on pin 9 to the servo object
}

void loop() {
  right.write(90); //resets servo to neutral position
  left.write(90); //resets servo to neutral position
  center.write(90); //resets servo to neutral position
  }

#include <ServoEasing.hpp> //makes sure to install in the same root library directory as servo.h is located in
#include <Servo.h>

//original code by Smalls 2024
//servoeasing library download link: https://www.arduino.cc/reference/en/libraries/servoeasing/
//servoeasing library documentation: https://github.com/ArminJo/ServoEasing 

ServoEasing breathe; //use this instead of Servo to define your object

void setup() {
  breathe.attach(2); //attaches the servo on pin 9 to the servo object  
  writeAllServos(90); //sets all servos to neutral middle position at boot
}

void loop() {
  breathe.attach(2); //attaches the servo on pin 9 to the servo object  
  breathe.setEasingType(EASE_QUARTIC_IN); //types of easing can be found at https://easings.net/ 
  breathe.easeTo(165, 45); //angle moved to and blocking aka time for arrival to the angle, lower the blocking number the slower the servo moves
  breathe.easeTo(90, 45); //sets servo back to neutral position
  breathe.detach(); //allows servo to rest and not hold a position if pressue is on it, preventing servo overheating 
}

Credits

Smalls

6 projects • 27 followers

Making stuff, breaking stuff, and learning everything I can. IG & TT: @smallswonderworks

Breathing Mechanism for Animatronic Puppets & Companion Bots