What is a closed loop stepper motor?

A closed loop stepper motor combines the straightforward operation of traditional stepper technology with the precise feedback and control found in servo systems. While open loop steppers operate without position feedback, closed loop models incorporate encoders to continuously monitor the motor’s position. This real-time feedback allows the system to automatically correct any deviations, resulting in greater repeatability, reliability, and dynamic response.

Benefits of closed loop stepper motors

Closed loop stepper motors offer a compelling balance of precision, reliability, and cost-effectiveness, making them an attractive choice for applications where open loop steppers fall short and full servo systems would be excessive.

Cost-Effective Performance:

Closed loop stepper motors offer motion control with accuracy and reliability compared to open loop steppers, approaching that of servo systems but without the higher expense and complexity.

Integration and Implementation Advantages:

These motors typically support various communication protocols and often feature simplified wiring. Their extra low voltage 24/48V DC power requirements can reduce installation complexity. Adaptable connectivity is a genuine advantage, making them compatible with different PLC platforms and control systems.

Application Flexibility:

Closed loop stepper motors are versatile and can be used in a wide range of applications, from small-scale to large-scale operations. Their scalable performance and technology-neutral approach allow users to select the best solution for specific needs. They are also well-suited to meet evolving industrial standards.

Positioning closed loop steppers vs servo motors

When choosing between closed loop stepper motors and servo motors, it’s important to consider key performance attributes such as torque characteristics, feedback capabilities, speed range, system complexity, cost, and integration options. The table below provides a high-level comparison:

Industrial applications: practical benefits

Closed loop stepper motors excel in industrial scenarios where precise position and torque control are mission-critical. Here are some more detailed examples:

• 3D Print Machines: Maintain exact tool paths and prevent missed steps, ensuring repeatable quality and minimizing downtime.
• Automated Assembly Lines: Achieve reliable positioning and automatic correction for disturbances, reducing defects and maintenance needs.
• Packaging and Bottling Lines: Simplify cabling and panel design with decentralized drive solutions, saving space and installation time while supporting consistent product flow.
• Robotics and Pick-and-Place Systems: Benefit from continuous feedback and real-time correction to prevent loss of synchronization, even under changing loads, resulting in higher uptime and consistent performance.

Modern advancements: Features and performance

Recent advancements have enabled the development of full servo systems based on stepper motor technology. For example, Festo’s EMMT-ST stepper motor paired with the CMMT-ST servo drive combines the straightforward design of a stepper with advanced servo functionality. This integration offers several key features:

Hardware Advancements

• Enhanced connectivity: Simplified cabling reduces installation complexity.
• Flexible encoder options: Single-turn and multi-turn batteryless encoders maintain position information, even through power cycles.
• Environmental protection: IP20 and IP65-rated motors are available for use in different environments.
• Holding brake option: Maintain position when powered down, supporting safety and process requirements.
• Safety functions: Features such as Safe Torque Off (STO) and Safe Stop 1 (SS1) help meet machine safety standards.
• UL certified for sale in the US market

Advanced Control Techniques

• Field orientated closed loop control: Enables precise management of torque, speed and position, similar to servo motors.
• Field weakening: Extends speed range and improves torque across a wider operating envelope, making these systems suitable for demanding applications.

With these advancements, closed loop stepper motors can deliver performance that closely approaches that of servo systems in many applications, while still retaining the cost and simplicity benefits of stepper technology.

Motor selection made easy

Selecting the right motor for your application doesn't have to be complicated. Festo's Electric Motion Sizing Tool takes the guesswork out of motor selection by:

• Allowing you to input specific application parameters such as load, stroke, speed, and cycle times.
• Automatically generating optimal motor and drive combinations from thousands of possibilities.
• Providing detailed performance graphs and cycle profiles to visualize your application.
• Offering immediate access to parameter settings and technical documentation.
• Enabling technology comparisons to evaluate energy consumption and total cost of ownership.

This interactive online tool ensures you select the optimal solution for your specific requirements.

Conclusion

To explore how closed loop stepper motors can enhance your automation setup, try our Electric Motion Sizing Tool or contact our technical team for personalized recommendations.