Stepper Motors vs Servo Motors: A Quick Comparison

Summary

Stepper motors start up in 200-400 milliseconds and have accuracy up to 25,600 steps per revolution, but lack feedback systems and can lose steps under overload. Servo motors start faster, have higher accuracy with encoder resolutions like 131,072 PES, and can handle overloads with closed-loop control. Stepper motors are more affordable and simpler, making them ideal for less demanding applications, while servo motors are more expensive and complex but offer superior performance.

Takeaways

• ⚡ Stepper motors generally take 200 to 400 milliseconds to start, while servo motors are much faster, starting in only a few milliseconds.
• 🎯 Stepper motor accuracy depends on the number of phases and subdivision control, with some achieving up to 25,600 steps per revolution.
• 🔍 Servo motors use an encoder for accuracy, and with a 17-digit encoder, they can achieve 131,072 pulses per revolution, offering higher precision.
• 🔄 Stepper motors operate in an open-loop system without feedback, while servo motors use closed-loop control with direct encoder feedback.
• ⚙️ Servo motors are more reliable for handling overloads, while stepper motors may lose steps when overloaded.
• 💸 Stepper motors are generally more affordable and simpler to operate than servo motors.
• 🔧 Servo motors are better for varying load applications due to their overload handling capabilities.
• 💻 Closed-loop control systems in servo motors make them more complex but also more reliable compared to open-loop stepper motors.
• 📉 Stepper motors are ideal for projects requiring simple operation, open-loop control, and minimal positional errors.
• 🔍 Servo motors outperform stepper motors in terms of speed, accuracy, and control, but they are more expensive and require additional components.

Q & A

What is the main difference in start-up speed between stepper motors and servo motors?

Stepper motors take 200 to 400 milliseconds to start up, whereas servo motors start several hundred times faster, taking only a few milliseconds.

How does the accuracy of stepper motors differ from servo motors?

Stepper motor accuracy depends on the number of phases and micro-step subdivisions, reaching up to 25,600 steps per revolution. Servo motor accuracy is determined by the encoder resolution, with a 17-digit encoder requiring 131,072 pulses for a full rotation.

What control system do stepper motors use?

Stepper motors typically operate with an open-loop control system, meaning they don't use feedback mechanisms to adjust their position.

How do servo motors differ from stepper motors in terms of control system?

Servo motors use a closed-loop control system, which employs feedback from the built-in encoder to ensure accurate positioning, making them more reliable than stepper motors.

Which type of motor is better suited for applications with varying loads?

Servo motors are better suited for applications with varying loads because they can withstand and overcome overload conditions, whereas stepper motors may lose steps when overloaded.

What is the typical overload capacity of stepper motors?

Stepper motors generally do not have the capacity to handle overloads and may lose steps when overloaded.

Why are servo motors considered more reliable than stepper motors?

Servo motors are considered more reliable because of their closed-loop control system, which uses real-time feedback to adjust positioning accurately, reducing the chance of errors.

How do the costs of stepper motors compare to servo motors?

Stepper motors are generally more affordable and simpler to operate compared to servo motors, which are more expensive and require additional components for closed-loop control.

Which motor type would be a better choice for a simple, low-cost project?

For simple, low-cost projects that do not require precise control or feedback, stepper motors would be a better choice due to their affordability and straightforward operation.

When is it better to choose a servo motor over a stepper motor?

It is better to choose a servo motor over a stepper motor when the application requires high accuracy, feedback control, and the ability to handle overloads, especially in projects with varying loads and demanding conditions.