What are servo motors? How do they work and their applications?

1.1 What is servomechanism?

A servo mechanism, also known as a servo system and commonly referred to as a “servo” is an automatic control system capable of adjusting its output based on feedback received. This allows it to achieve exceptional precision in controlling the position, speed, and overall motion of an object. Fundamentally, a servo mechanism is a feedback control system comprising a sensor, a controller, and an actuator:

• Sensor: Measures the position or speed of the object and sends this information to the controller, where it is processed to determine the necessary adjustments.
• Actuator: Typically, a servo motor executes these adjustments to align the actual output with the desired output.

The outstanding feature of a servo mechanism is its ability to correct errors in real time. This is achieved through negative feedback, where the system continuously compares the desired action with the actual action and minimizes the error between them. This ongoing adjustment process enables the servo mechanism to maintain precise control over the systems it governs, making it an indispensable component of modern technology.

1.2 What are servo motors?

A servo motor is an integral part of a servo system. It is a type of rotary or linear motor that receives power from a servo amplifier and generates torque or force to act on a mechanical system, such as an actuator or brake.

Servo motors enable precise control of parameters like angular position, acceleration, and speed. They operate within a closed-loop control system, where the current output is monitored and adjusted to achieve the desired state. In this system, control actions are based on the motor's output, employing positive feedback to regulate movement and the final position of the motor shaft.

Servo motors provide high flexibility in manufacturing environments. Typical applications include collaborative robots (cobots), conveyors, automatic doors, CNC machines, radar systems, tracking systems, and various automation systems.

1.3 Structure and operating principles of servo motors

A servo motor is composed of two windings:

• Stator: Wrapped around the fixed part of the motor, also known as the motor's magnetic field winding.
• Rotor: Wrapped around the rotating part of the motor, also referred to as the motor's armature winding.

The motor includes two bearings at the front and rear to allow the shaft to rotate freely. An encoder, integrated with a proximity sensor, is used to determine the motor's rotational speed and the number of revolutions per minute (RPM).

Servo motors operate within a closed-loop system, receiving commands from the servo controller and utilizing feedback devices to close the control loop. Together, the motor, controller, and feedback device form a servomechanism. The controller sends commands to the motor, causing it to move. The encoder provides feedback (such as current, speed, or the motor's current position) to the controller. The controller compares the feedback data with the command parameters and adjusts the motor's operation as needed to maintain precision.

Compact and efficient, yet servo motors play a crucial role in applications requiring precise position control. They are widely used in tasks that demand high-accuracy repetitive operations:

• Robots: Servo motors are used to initiate motion and position robotic arms at precise angles.
• Conveyor belts: Servo motors control the movement of conveyor belts, allowing products to pass through various production stages and stop or start at exact points, such as during labeling, bottling, or packaging processes.
• Cameras: Integrated into cameras to adjust lenses and improve focus, reducing image blurriness.
• Automatic doors: Operate automatic doors in supermarkets, hospitals, and cinemas.
• Textile industry: Control knitting machines, looms, and machines for spinning or weaving fabrics.
• Solar tracking systems: Used to adjust the tilt angle of solar panels, ensuring they remain aligned with the sun.
• Metalworking machines: Provide precise motion control for milling, cutting, and other metalworking equipment.

4.1 The role of cables in servo motors

Servo motor cables are specialized cables used to transmit power and control signals between servo motors and controllers or actuators. They ensure continuous electrical signal transmission, supporting precise control of position, speed, and torque in servo motor systems.

Servo motor cables are designed to withstand constant movement and harsh operating conditions commonly found in industrial automation and robotics applications. These cables not only ensure signal stability but also provide high durability and reliable performance in complex environments.

4.2 Types of cables used for servo motors

The types of cables used for servo motors include:

• Power cables: Used to transmit the electrical energy required for the servo motor. These cables typically have a larger cross-section to ensure they can carry sufficient current to meet the motor's operational demands.
• Feedback cables: Connect the servo motor to feedback devices, enabling real-time monitoring of parameters such as position, speed, and motor operating status for closed-loop control.
• Control cables: Transmit control signals and connect the servo motor to the controller.