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 Systems: Used in conveyor belts, pick-and-place machines, and other automated systems.
• Camera Gimbals: For stabilizing and controlling camera angles.
• 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 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)
• 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)

1. Connect the Servo to a Power Source:
   • Connect the VCC pin to a 5V power supply (or 6V if supported by the servo).
   • 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:
     • 1ms pulse: 0° position
     • 1.5ms pulse: 90° position
     • 2ms pulse: 180° position

• Power Supply: Ensure the servo has a stable power supply. Using a separate power source for the servo (instead of powering it directly from the microcontroller) is recommended to avoid voltage drops.
• Current Requirements: High-torque servos may draw significant current under load. Use a power supply capable of providing sufficient current.
• Signal Timing: Ensure the PWM signal frequency is set to 50Hz for standard servos.
• Avoid Overloading: Do not exceed the torque rating of the servo to prevent damage.

Below is an example code to control a servo using an Arduino UNO and the Servo library.

#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 the process of generating PWM signals for controlling the servo.
• The myServo.attach(9) function links the servo to pin 9, which must be a PWM-capable pin.
• The myServo.write(angle) function sets the servo to a specific angle (0° to 180°).

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 voltage and current requirements.

2. Jittery or Erratic Movement:

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

3. Servo Overheating:

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

4. Servo Not Responding to PWM Signal:

   • Cause: Incorrect PWM frequency or pulse width.
   • Solution: Ensure the PWM signal is set to 50Hz and the pulse width is within the 1ms to 2ms range.

Q: Can I power the servo directly from the Arduino?
A: While it is possible for small, low-power servos, it is not recommended. Servos can draw significant current, which may exceed the Arduino's power output capacity. Use an external power supply for reliable operation.

Q: Can I control multiple servos with one Arduino?
A: Yes, you can control multiple servos using the Servo library. However, ensure your power supply can handle the combined current draw of all servos.

Q: What is the difference between a standard servo and a continuous rotation servo?
A: A standard servo is used for precise angular positioning (0° to 180°), while a continuous rotation servo is used for speed and direction control, similar to a DC motor.

Q: How do I increase the torque of my servo?
A: You cannot increase the torque of a servo beyond its rated capacity. If more torque is needed, use a servo with a higher torque rating.