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: Used for controlling robotic arms, grippers, and joints.
• RC Vehicles: Steering mechanisms in cars, planes, and boats.
• Automation: Positioning systems in conveyor belts and manufacturing equipment.
• DIY Projects: Commonly used in hobbyist projects for creating moving parts.
• Camera Gimbals: Stabilizing and positioning cameras for smooth motion.

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 range)
• Operating Current: 100mA to 1A (depending on load)
• Torque: 1.5 kg-cm to 20 kg-cm (varies by model)
• Rotation Range: 0° to 180° (standard), 360° for continuous rotation servos
• Control Signal: Pulse Width Modulation (PWM)
• Pulse Width Range: 1ms (0°) to 2ms (180°)
• Neutral Position: 1.5ms (90°)
• 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 PWM-capable pin on your microcontroller (e.g., Arduino).
3. PWM Signal: Generate a PWM signal with a pulse width between 1ms and 2ms to control the servo's position:
   • 1ms corresponds to 0°.
   • 1.5ms corresponds to 90° (neutral position).
   • 2ms corresponds to 180°.

• Power Supply: Use a separate power supply for the servo if it draws significant current, as it may cause voltage drops in your circuit.
• Avoid Overloading: Do not exceed the torque rating of the servo to prevent damage.
• Signal Stability: Ensure the PWM signal is stable and within the specified range to avoid erratic behavior.
• Continuous Rotation Servos: For continuous rotation servos, the PWM signal controls speed and direction rather than position.

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 library simplifies controlling the servo.
• The attach() function links the servo to a specific PWM pin.
• The write() function sets the servo's position in degrees (0° to 180°).
• Delays are used to allow the servo to reach the desired position before the next command.

1. Servo Not Moving:

   • Cause: Insufficient power supply.
   • Solution: Use a dedicated power source with sufficient current capacity.

2. Erratic Movement:

   • Cause: Unstable or noisy PWM signal.
   • Solution: Check the signal source and ensure proper grounding.

3. Overheating:

   • Cause: Overloading the servo or running it continuously at high torque.
   • Solution: Reduce the load or use a higher-torque servo.

4. Limited Range of Motion:

   • Cause: Incorrect PWM signal range.
   • Solution: Verify the pulse width range (1ms to 2ms) and adjust your code.

• Q: Can I power the servo directly from the Arduino?

  • A: While possible for small servos, it is not recommended for larger servos due to current limitations. Use an external power supply.

• Q: How do I control a continuous rotation servo?

  • A: Instead of position, the PWM signal controls speed and direction. A 1.5ms pulse stops the servo, while shorter or longer pulses control direction and speed.

• Q: Can I connect multiple servos to a single Arduino?

  • A: Yes, but ensure the power supply can handle the combined current draw of all servos.

• Q: What happens if I send a pulse width outside the 1ms to 2ms range?

  • A: The servo may behave unpredictably or stop responding. Always stay within the specified range.

This documentation provides a comprehensive guide to understanding and using a servo in your projects. Follow the guidelines and best practices to ensure optimal performance and longevity of your servo.