What is a servo? Analysis of the internal structure of the servo

What is a servo motor? First, the name "servo motor" is actually a colloquial term coined by those who play with model aircrafts and boats, as this type of motor is often used for rudder control. A servo motor is essentially a simple servo system, and it is also the most common type of servo system.

A servo motor is a position (angle) servo driver suitable for control systems that require continuous angle changes and can maintain them. It consists of a housing (upper, middle, and lower shells), control circuitry, a motor, a gearset, a position sensor, and bearings. A servo motor is a closed-loop control system. The control circuit board receives control signals from the signal line, controlling the motor to rotate. The motor drives a series of gearsets, decelerates, and transmits the movement to the output rudder. The output shaft of the servo motor is connected to a position feedback potentiometer (or magnetic encoder, etc.). As the rudder rotates, it drives the position feedback potentiometer, which outputs a voltage signal to the control circuit board for feedback. Then, the control circuit board determines the direction and speed of motor rotation based on the current position to achieve the target stop.

If it's still not intuitive enough, let's take a look at a disassembly diagram of a servo motor.

Next, let's introduce the structural components of a servo motor in detail, which work together to achieve its functionality:

  1. Housing:

• The external protective structure of the servo motor, usually made of metal or sturdy plastic.

• Protects internal components from external environments such as dust, moisture, and impacts.

  2. DC Motor:

• The power source of the servo motor, providing the necessary rotational torque.

• The type, power, and speed of the DC motor depend on the specific application scenario of the servo motor.

  3. Gear Reduction Set:

• Located between the DC motor and the output shaft, used to reduce the motor's speed and amplify torque.

• The gear reduction set usually consists of multiple gears, achieving a larger torque output and slower rotation speed.

• The precision and wear resistance of the gears are crucial to the performance and lifespan of the servo motor.

  4. Angle Sensor (Potentiometer, Magnetic Encoder):

• A potentiometer reflects the angular position of the servo motor through changes in its resistance value.

• A magnetic encoder uses magnetic field sensors to achieve angle measurement.

• As the magnetic encoder rotates, the magnetic field of the magnetic material also changes, and the sensor detects the change in the magnetic field to output corresponding pulse signals.

• The precision and stability of the angle sensor directly affect the control precision and stability of the servo motor.

  5. Control and Drive Circuitry:

• The core part of the servo motor, receiving signals (such as PWM signals) from external interfaces and voltage values fed back by the angle sensor.

• After processing, the control and drive circuitry drives the DC motor to rotate and ensures the servo motor works accurately and stably through closed-loop control.

• The control and drive circuitry also handles motor overcurrent, overheat, and other protective functions to ensure the safe operation of the servo motor.

  6. Interface Cables:

• Used to connect the servo motor to external control systems (such as remote controllers, computers, etc.).

• Interface cables typically include power lines, ground lines, control signal lines, etc., for transmitting electrical power and control signals.

  7. Rudder/Rocker Arm:

• Connected to the output shaft of the servo motor, it is the component that connects the servo motor to external mechanical structures.

• The rudder converts the rotational movement of the servo motor into linear movement or angle changes to meet different application needs.

• The position and angle of the rudder can be precisely adjusted through external control signals.

  8.  Other Components:

• Depending on the specific application scenario and performance requirements of the servo motor, it may also include other components such as feedback potentiometer brackets, gear fixing seats, bearings, etc. In terms of performance, it can also be customized according to customer needs, such as waterproofing, high and low temperature resistance.
  
  

In summary:
A servo motor is a position (angle) servo driver composed of components such as a housing, rudder, DC motor, gear reduction set, angle sensor, control and drive circuitry, and interface cables. These components work together to enable the servo motor to accurately and stably achieve angle changes, widely used in drones, robots, household appliances, automation equipment, STEAM education, military aerospace, and other fields. In practical applications, the performance parameters (such as torque, speed, precision, etc.) and interface types (such as command signals, digital signals, etc.) of the servo motor can be selected according to specific needs.