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.
• RC Vehicles: Steering and throttle control in remote-controlled cars, boats, and planes.
• Automation: Used in conveyor systems, camera gimbals, and automated manufacturing.
• DIY Projects: Popular in hobbyist projects involving Arduino and other microcontrollers.

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 6.0V (typical range)
• Torque: 1.5 kg-cm to 20 kg-cm (varies by model)
• Speed: 0.1 to 0.2 seconds per 60° (at rated voltage)
• Control Signal: Pulse Width Modulation (PWM)
• Angle Range: 0° to 180° (standard), some models support 360° continuous rotation
• Connector Type: 3-pin (Signal, VCC, GND)

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

1. Connect the Servo to a Power Source:
   • Connect the VCC pin to a 5V power supply (or as specified by the servo's datasheet).
   • Connect the GND pin to the ground of the power supply and the microcontroller.
2. Connect the Signal Pin:
   • Connect the Signal pin to a PWM-capable pin on your microcontroller (e.g., Arduino).
3. Control the Servo:
   • Use PWM signals to control the servo's position. The pulse width determines the angle:
     • 1 ms pulse: 0° position
     • 1.5 ms pulse: 90° position (center)
     • 2 ms pulse: 180° position

• Power Supply: Ensure the power supply can provide sufficient current for the servo. High-torque servos may require up to 2A.
• Avoid Overloading: Do not exceed the torque rating of the servo to prevent damage.
• PWM Signal: 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's power regulator.

Below is an example code 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
}

• 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: Incorrect wiring or insufficient power supply.
   • Solution: Double-check connections and ensure the power supply meets the servo's requirements.

2. Jittery or Erratic Movements:

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

3. Overheating:

   • Cause: Overloading the servo or continuous operation at high torque.
   • Solution: Reduce the load or allow the servo to cool down periodically.

4. Limited Range of Motion:

   • Cause: Mechanical obstruction or incorrect PWM signal.
   • Solution: Check for physical obstructions and verify the PWM signal's pulse width.

Q1: Can I connect multiple servos to an Arduino?
A1: Yes, but ensure the power supply can handle the combined current draw. Use an external power source if needed.

Q2: Can a servo rotate continuously?
A2: Standard servos have a limited range (0° to 180°). Continuous rotation servos are available for applications requiring full 360° motion.

Q3: How do I know the torque required for my application?
A3: Calculate the torque based on the load and lever arm length. Choose a servo with a torque rating higher than your calculated requirement.

Q4: Can I use a servo without a microcontroller?
A4: Yes, you can use a servo tester or a circuit that generates PWM signals to control the servo without a microcontroller.