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 and precise positioning tasks.
• Hobby projects: Model airplanes, boats, and cars.
• Camera gimbals: Stabilization and precise movement.

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

• Operating Voltage: 4.8V to 6V (typical for standard servos)
• Operating Current: 100mA to 1A (depending on load)
• Torque: 1.5 kg-cm to 20 kg-cm (varies by model)
• Speed: 0.1s to 0.2s per 60° (at no load)
• Control Signal: Pulse Width Modulation (PWM)
• Angle Range: 0° to 180° (standard), 360° for continuous rotation servos
• Connector Type: 3-pin (Signal, VCC, GND)

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

1. Power the Servo: Connect the VCC pin to a 5V or 6V power source and the GND pin to the ground of your circuit.
2. Control Signal: Connect the Signal pin to a microcontroller or PWM signal generator.
3. PWM Signal: Use a PWM signal with a frequency of 50Hz (20ms period). The pulse width determines the servo's position:
   • 1ms pulse: 0° position
   • 1.5ms pulse: 90° position (center)
   • 2ms pulse: 180° position

• Power Supply: Ensure the power supply can handle the servo's current requirements, 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 jittery or erratic movements.
• External Power: For multiple servos, use an external power source to avoid overloading the microcontroller.

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 to control the servo

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: Double-check the connections and ensure the power supply meets the servo's requirements.

2. Jittery or Erratic Movement

   • 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 or allow the servo to cool down periodically.

4. Limited Range of Motion

   • Cause: Servo is mechanically restricted or receiving incorrect PWM signals.
   • Solution: Check for physical obstructions and verify the PWM signal's pulse width.

Q: Can I power the servo directly from the Arduino?
A: While possible for small servos, it is not recommended for larger or multiple servos due to current limitations. Use an external power source.

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 total current draw.

Q: What is the difference between a standard servo and a continuous rotation servo?
A: A standard servo moves to a specific angle based on the PWM signal, while a continuous rotation servo rotates continuously in either direction, with the PWM signal controlling speed and direction.

Q: Can I use a servo without a microcontroller?
A: Yes, you can use a standalone PWM signal generator to control the servo.