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: Controlling robotic arms, grippers, and joints.
• RC Vehicles: Steering and throttle control in remote-controlled cars, boats, and planes.
• Automation: Positioning systems in conveyor belts and manufacturing equipment.
• DIY Projects: Automated doors, camera gimbals, and hobbyist creations.
• Prosthetics: Actuating artificial limbs for 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 range)
• Current Draw: 10mA to 1A (depending on load)
• Torque: 1.5 kg-cm to 25 kg-cm (varies by model)
• Rotation Range: 0° to 180° (standard), 360° for continuous rotation servos
• Control Signal: Pulse Width Modulation (PWM)
  • Pulse width: 1ms (0°), 1.5ms (90°), 2ms (180°)
  • Frequency: 50Hz (20ms period)
• Connector: 3-pin (Signal, VCC, GND)

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

1. Connect the Servo:

   • Connect the Signal pin to a PWM-capable pin on your microcontroller (e.g., Arduino).
   • Connect the VCC pin to a 5V power source.
   • Connect the GND pin to the ground of your circuit.

2. Generate PWM Signal:

   • Use a microcontroller to generate a PWM signal with a frequency of 50Hz.
   • Adjust the pulse width to control the servo's position:
     • 1ms pulse: 0° position
     • 1.5ms pulse: 90° position
     • 2ms pulse: 180° position

3. Power Considerations:

   • If the servo draws high current, use an external power supply instead of powering it directly from 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

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

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

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

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

• Avoid Overloading: Do not exceed the torque rating of the servo to prevent damage.
• Use Proper Power Supply: Ensure the power supply can handle the servo's current draw, especially under load.
• Secure Mounting: Mount the servo securely to avoid vibrations or misalignment.
• Calibrate the Servo: If the servo does not reach the desired position, adjust the pulse width or use a calibration routine.

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. Servo Jittering:

   • Cause: Electrical noise or unstable power supply.
   • Solution: Add a capacitor (e.g., 100µF) across the power supply to stabilize it.

3. Servo Overheating:

   • Cause: Prolonged operation under high load.
   • Solution: Reduce the load or use a servo with a higher torque rating.

4. Servo Not Reaching Full Range:

   • Cause: Incorrect PWM signal or mechanical obstruction.
   • Solution: Verify the PWM signal timing and check for physical obstructions.

• Q: Can I control multiple servos with one microcontroller?

  • A: Yes, most microcontrollers can control multiple servos using separate PWM pins or a servo driver module.

• Q: What is the difference between a standard and a continuous rotation servo?

  • A: A standard servo has a limited rotation range (e.g., 0° to 180°), while a continuous rotation servo can rotate 360° and is controlled by speed and direction rather than position.

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

  • A: It is not recommended for high-torque servos, as they may draw more current than the Arduino can supply. Use an external power source instead.

• Q: How do I know if my servo is compatible with my project?

  • A: Check the servo's voltage, torque, and size specifications to ensure they meet your project's requirements.