Servo motors: precise control for robotics, modelling and manufacturing

Servo motors can be divided into several categories, which differ in their design and function. Here is an overview of the main types:

• DC servo motors: These motors work with a DC power source and offer a fast response time and easy control. They are often used in robotics and model making.
• AC servo motors: These use alternating current and are particularly suitable for industrial applications where high performance and precision are required.
• Synchronous servo motors: These operate with a fixed phase relationship between the rotating field and rotor motion and are characterised by high efficiency and accuracy, making them ideal for automation systems.
• Asynchronous servo motors: These motors are often used in variable-speed applications and provide a robust and cost-effective solution for industrial control systems.
• Brushless servo motors: These motors have no brushes, making them particularly durable and low maintenance. They are suitable for applications that require high speeds and low friction, such as CNC machines or high-end robotic systems.

A servo motor consists of several essential components that ensure its precise control and functionality:

• Rotor: The moving element of the motor that performs the rotary motion.
• Stator: The fixed part of the motor that generates the magnetic field.
• Position sensor: Continuously measures the current position of the rotor and sends this data to the servo drive.
• Servo drive: The central control unit that evaluates the position data and makes the necessary corrections.
• Power stage: Converts electrical signals into the power needed to drive the motor.

A servo motor works on the principle of closed-loop control. The servo controller receives control commands from a higher-level control unit and converts them into precise movements. At the same time, the position sensor continuously transmits measured values to the controller, which then makes adjustments to maintain the desired position or speed exactly. This enables the servo motor to achieve a high level of precision and stability, even with dynamic loads or changing requirements.

A servo motor is controlled by an external control unit that specifies the desired motion sequences. This can be done in a number of ways:

• Microcontrollers (e.g. Arduino, Raspberry Pi): These allow flexible and programmable control, often for robotics and automation applications.
• Industrial controllers (e.g. PLC systems): These are used in professional manufacturing systems and offer highly precise control.
• Manual controllers: These can be used to control a servomotor directly via potentiometers or joysticks.
• The control is usually done via pulse width modulation (PWM) to determine the desired position or speed of rotation exactly.
• With control systems such as Arduino or other control units, the motor can be controlled precisely.