How to Use servo: Examples, Pinouts, and Specs

A servo is a rotary actuator that allows for precise control of angular position, velocity, and acceleration. It consists of a motor coupled to a sensor for position feedback, along with a control circuit. Servos are widely used in robotics, automation, remote-controlled vehicles, and industrial machinery due to their ability to provide accurate and repeatable motion.

• Robotics: For controlling robotic arms, grippers, and joints.
• Remote-controlled vehicles: Steering mechanisms and throttle control.
• Automation: Conveyor systems, camera gimbals, and automated doors.
• Hobby projects: Model airplanes, boats, and cars.
• Industrial machinery: Precision positioning in manufacturing processes.

Below are the general technical specifications for a standard servo. Note that specific values may vary depending on the model and manufacturer.

The servo typically has a 3-pin connector with the following pinout:

1. Power the Servo: Connect the VCC pin to a 5V power source and the GND pin to the ground of your circuit.
2. Control Signal: Connect the Signal pin to a microcontroller (e.g., Arduino) capable of generating a PWM signal.
3. PWM Signal: Use a PWM signal with a frequency of 50 Hz. The pulse width determines the servo's position:
   • 1 ms pulse width: 0° position.
   • 1.5 ms pulse width: 90° position (center).
   • 2 ms pulse width: 180° position.

• Power Supply: Ensure the power supply can provide sufficient current for the servo, especially under load.
• Avoid Overloading: Do not exceed the torque rating of the servo to prevent damage.
• Signal Stability: Use a stable PWM signal to avoid erratic movements.
• Mechanical Limits: Avoid forcing the servo beyond its physical limits to prevent damage to the gears.

Below is an example of how to control a servo using an Arduino UNO:

#include <Servo.h> // Include the Servo library

Servo myServo; // Create a Servo object

void setup() {
  myServo.attach(9); // Attach the servo to pin 9 on the Arduino
}

void loop() {
  myServo.write(0); // Move the servo to 0 degrees
  delay(1000);      // Wait for 1 second

  myServo.write(90); // Move the servo to 90 degrees
  delay(1000);       // Wait for 1 second

  myServo.write(180); // Move the servo to 180 degrees
  delay(1000);        // Wait for 1 second
}

• The Servo.h library simplifies servo control by handling PWM signal generation.
• Ensure the servo is connected to a pin capable of PWM output (e.g., pin 9 on the Arduino UNO).

1. Servo Not Moving

   • Cause: Incorrect wiring or insufficient power supply.
   • Solution: Verify the connections and ensure the power supply meets the servo's requirements.

2. Erratic Movements

   • Cause: Unstable PWM signal or electrical noise.
   • Solution: Use a decoupling capacitor near the servo's power pins and ensure a stable PWM signal.

3. Overheating

   • Cause: Overloading the servo or continuous operation under high torque.
   • Solution: Reduce the load on the servo and allow it to cool periodically.

4. Limited Range of Motion

   • Cause: Mechanical obstruction or incorrect PWM signal.
   • Solution: Check for physical obstructions and ensure the PWM signal is within the correct range (1 ms to 2 ms).

Q: Can I power the servo directly from the Arduino?
A: While possible for small servos, it is not recommended. Use an external power supply to avoid overloading the Arduino's voltage regulator.

Q: How do I control multiple servos with an Arduino?
A: Use the Servo.h library to create multiple Servo objects, each controlling a different servo. Ensure the power supply can handle the combined current draw.

Q: Can I rotate the servo beyond 180°?
A: Standard servos are limited to 180°. For continuous rotation, use a modified or continuous rotation servo.

Q: Why is my servo jittering?
A: This could be due to electrical noise, insufficient power, or an unstable PWM signal. Check your circuit and power supply.

By following this documentation, you can effectively integrate and troubleshoot a servo in your projects.