Pan and tilt control with 2 servo motors

[bananacream]

Hi,
I'm trying to use 2 servo motors (Tower Pro SG-5010) in a pan and tilt kit using the Arduino Uno with the motor driver shield L293D. Below is the code I'm currently using that I retrieved off a similar project with the servo motors connected to pins 9 & 10 on the L293D:
( Charles' Labs - 3D Lidar Scanner )

But, when using the below code only the yaw servo motor seems to be moving 180° in a continuous loop. I've checked both pins (9 & 10) with the example servo sweep code and they to work with no issue individually.

The goal is two be able to yaw sweep 180° and back to 0° then move up 1° in pitch - to a maximum of 45° pitch angle. This would enable me to attach a LiDAR scanner later on and scan a small slope.

Any help would be greatly appreciated!

#include <Servo.h>
#include <Wire.h>

//Delay between each sample to avoid mechanical wobble
#define DELAY_BETWEEN_SAMPLES 100
//Size of the steps of YAW/PITCH in degrees (1 = full res)
#define YAW_STEP 1
#define PITCH_STEP 1
#define MATH_PI 3.1415f

//Variables

Servo servoYaw,servoPitch;
char s[15];
int yawAngle,pitchAngle;

void setup() {
  // Initialize serial connection to display distance readings
  Serial.begin(115200); 

  //Servo init
  servoYaw.attach(10);
  servoPitch.attach(9);

  
}

void loop() {
  delay(5000);
  //Sweep Yaw servomotor
  for (yawAngle = 0; yawAngle <= 180; yawAngle += YAW_STEP) {
    servoYaw.write(yawAngle);
    
    //Sweep Pitch servomotor. The direction depends on the current directory
    if(pitchAngle < 90){
      for (pitchAngle = 0; pitchAngle <= 180;pitchAngle+= PITCH_STEP){
        servoPitch.write(pitchAngle);
      
      }
 
       
      }
    }
  }

[groundFungus]

Servos need an external power supply. A 4 AA battery pack is a popular servo supply.

What happens if attach the servos directly to pins 9 and 10, bypassing the shield?

[bananacream]

Thanks for the reply - I connected an external power supply but, I'm still experiencing the same issue.
I also originally tried without using the shield and had the same problem. Not sure what to try next?

[slipstick]

@bananacream

    //Sweep Pitch servomotor. The direction depends on the current directory
    if(pitchAngle < 90){
      for (pitchAngle = 0; pitchAngle <= 180;pitchAngle+= PITCH_STEP){
        servoPitch.write(pitchAngle);
      }
   }

You never do any reversing. So yaw sweeps to 180 then jumps back to 0 and starts again. And after the first 1 degree yaw move pitch will sweep to 180 so after that pitchAngle is 180 (i.e. not < 90) so it never moves again. I can't see any mention of 45 anywhere.

Steve

[johnwasser]

@bananacream

    //Sweep Pitch servomotor. The direction depends on the current directory
    if(pitchAngle < 90){
      for (pitchAngle = 0; pitchAngle <= 180;pitchAngle+= PITCH_STEP){
        servoPitch.write(pitchAngle);
      }
    }

This pitch sweep will only happen once. After that, 'pitchAngle' is 181 so the "if(pitchAngle < 90)" is never true again.

You should put the pitch loop AROUND the yaw loop so it does a yaw scan at each pitch:

  // The goal is two be able to yaw sweep 180° and
  // back to 0° then move up 1° in pitch - to a 
  // maximum of 45° pitch angle. 
  for (pitchAngle = 0; pitchAngle <= 45; pitchAngle+= PITCH_STEP)
  {
    servoPitch.write(pitchAngle);

    //Sweep Yaw servomotor
    for (yawAngle = 0; yawAngle <= 180; yawAngle += YAW_STEP) 
    {
      servoYaw.write(yawAngle);
      // Take sample?
    }
  }