Butterfly Effect

Using Arduino Project Guidance
1

This post has nothing to do with the chaos theory of the "butterfly effect" or the movie but a simple butterfly made with servos!

I have the code below that allows for two servos, side by side, to "flap" like wings so to speak between 0 and 40 degress (the servo horn/arm has been connected at a certain angle so each arm mirrors one another)

#include <Servo.h> 

Servo servo1;  
Servo servo2; 

int pos1;      
int pos2;     

void setup() 
{ 
 servo1.attach(10);   
 servo2.attach(8);  
} 

void loop() 
{ 
delay(1000);
     // Scene 1: 
 for (int i=0; i<40; i += 1) {
   pos1 = i;              
   pos2 = 40 - i;           
   
   servo1.write(pos1);
   servo2.write(pos2); 
   delay(5);                            
 }
  for (int i=40; i>=0; i -= 1) {
   pos1 = i;                  
   pos2 = 40 - i;              
   servo1.write(pos1);
   servo2.write(pos2); 
   delay(5);                           
 }
  for (int i=0; i<40; i += 1) {
   pos1 = i;              
   pos2 = 40 - i;           
   
   servo1.write(pos1);
   servo2.write(pos2); 
   delay(5);                             
 }
  for (int i=40; i>=0; i -= 1) {
   pos1 = i;               
   pos2 = 40 - i;             
   servo1.write(pos1);
   servo2.write(pos2); 
   delay(5);                          
 }
 delay (1000);
  for (int i=0; i<40; i += 1) {
   pos1 = i;              
   pos2 = 40 - i;           
   
   servo1.write(pos1);
   servo2.write(pos2); 
   delay(15);                            
 }
  for (int i=40; i>=0; i -= 1) {
   pos1 = i;                 
   pos2 = 40 - i;             
   servo1.write(pos1);
   servo2.write(pos2); 
   delay(15);                           
 }
 
}

This is for one butterfly, but I would like 3 going at once (so 6 servos) but don't want them all doing the same thing at once (perhaps the second butterfly does the same thing but starts 1 second after the first butterfly etc). I've had a look at using millis but I'm pretty stumped at how to go about it.

Any help would be much appreciated!

2

zakgatara:
This post has nothing to do with the chaos theory of the "butterfly effect" or the movie but a simple butterfly made with servos!

I have the code below that allows for two servos, side by side, to "flap" like wings so to speak between 0 and 40 degress (the servo horn/arm has been connected at a certain angle so each arm mirrors one another)

#include <Servo.h>

Servo servo1;  
Servo servo2;

int pos1;      
int pos2;

void setup()
{
servo1.attach(10);  
servo2.attach(8);  
}

void loop()
{
delay(1000);
    // Scene 1:
for (int i=0; i<40; i += 1) {
  pos1 = i;              
  pos2 = 40 - i;          
 
  servo1.write(pos1);
  servo2.write(pos2);
  delay(5);                            
}
 for (int i=40; i>=0; i -= 1) {
  pos1 = i;                  
  pos2 = 40 - i;              
  servo1.write(pos1);
  servo2.write(pos2);
  delay(5);                          
}
 for (int i=0; i<40; i += 1) {
  pos1 = i;              
  pos2 = 40 - i;          
 
  servo1.write(pos1);
  servo2.write(pos2);
  delay(5);                            
}
 for (int i=40; i>=0; i -= 1) {
  pos1 = i;              
  pos2 = 40 - i;            
  servo1.write(pos1);
  servo2.write(pos2);
  delay(5);                          
}
delay (1000);
 for (int i=0; i<40; i += 1) {
  pos1 = i;              
  pos2 = 40 - i;          
 
  servo1.write(pos1);
  servo2.write(pos2);
  delay(15);                            
}
 for (int i=40; i>=0; i -= 1) {
  pos1 = i;                
  pos2 = 40 - i;            
  servo1.write(pos1);
  servo2.write(pos2);
  delay(15);                          
}

}




This is for one butterfly, but I would like 3 going at once (so 6 servos) but don't want them all doing the same thing at once (perhaps the second butterfly does the same thing but starts 1 second after the first butterfly etc). I've had a look at using millis but I'm pretty stumped at how to go about it. 

Any help would be much appreciated!

What if you create functions like

void butterfly1Flap(){
//all servo stuff
}

void butterfly2Flap(){
//all servo stuff
}

void butterfly3Flap(){
//all servo stuff
}

and call these inside the loop like

void loop(){
butterfly1Flap()
delay(xx);
butterfly2Flap()
delay(xx);
butterfly3Flap()
delay(xx);
}
3

Won't it run through each function entirely before starting the next one? I will try now, hopefully it works!

4

First, I suggest you simplify things by using a single servo to flap both wings - butterly wings move in sync with each other.

Second, for the sort of thing you want there should not be a delay() function anywhere in your program. Have a look at how millis() is used to manage timing in Several Things at a Time

That demo also includes a servo example.

If you want to move several servos at the same time you need to interleave their movements. For example

if (currentMillis - previousServoMillis >= servoInterval) {
       // its time for another move
   previousServoMillis += servoInterval;
   
   servoPosition = servoPosition + servoDegrees; // servoDegrees might be negative
   servo2Position = servo2Position + servo2Degrees; // servo2Degrees might be negative
   // etc

...R
PS. Your surmise in Reply #2 is quite correct.

5

The milliselapsed library takes a bit of the load off the coding, by hiding some of the arithmetic of Robin2's code. (It does that previous and current millis stuff under the hood.... no different really, just hides stuff.)