POSITAL Kit Encoders for Stepper Motors

July 3, 2019

While servomotors remain the gold standard for precision motion control in industrial machinery, the improved performance of stepper motors is making these lower-cost devices an increasingly attractive alternative for many applications. The key to these performance gains is the addition of rotation-measuring encoders, especially the new absolute multi-turn kit encoders from POSITAL.

Stepper motors are brushless DC motors that turn their shaft by a small fixed amount (step) in response to a control signal. However, this is an open loop control system: if the motor fails to complete a step (e.g. due to unexpected mechanical resistance) system accuracy is degraded. This can be overcome by adding a simple incremental encoder to provide feedback as to whether step motions have occurred. POSITAL’s new magnetic encoders take this a step further by providing absolute position feedback. (With incremental feedback, control system needs to keep an accurate count of the number of steps in order to track the absolute rotary position of the motor shaft. If this count is lost or corrupted – e.g. due to a power interruption – knowledge of the position of machine components is also lost. It is usually necessary to return the machinery to a known starting position and re-initiate the step count. By contrast, with absolute measurement systems, complete position measurements are available whenever the control system queries the encoders. Production processes can be restarted directly with minimal loss of time and materials.)

POSITAL’s absolute kit encoders are available with multi-turn measurement ranges, which can be very useful when a motor is connected to a screw shaft, cable drum or gear reduction system. The multi-turn rotation counter is self-powered, using POSITAL’s Wiegand energy harvesting technology. The rotation count is always up-to-date, even if the machine has moved while control system power was out. No backup batteries are required!

POSITAL’s encoders for stepper motors are “kit” or modular devices, designed to be integrated into a motor housing, measuring the rotary position directly from the drive shaft. Kit packages are available with the same mounting form factor as popular incremental encoders for NEMA-standard stepper motors, making these encoders convenient drop-in replacements for less advanced incremental encoders. The magnetic measurement module is compact (37 mm diameter, 23 mm deep) and highly resistant to dust, moisture and shock/vibration loading. Shields are available to protect the measurement module from external magnetic fields. SSI and the more advanced “BiSS C” communication interfaces have been implemented. Both are open-source interfaces that are compatible with a wide range of PLC’s and computers.

Stepper motors with built-in position sensors are an increasingly attractive solution for positioning tasks in manufacturing equipment, packaging machinery, robots and other applications where a reliable, cost-efficient drive mechanism is needed.

www.fraba.com

Related Articles



Editor’s Pick: Featured Article

Weidmüller’s u-control 2000: The Automation Controller

Weidmüller’s u-control 2000: The Automation Controller

Weidmüller’s scalable engineering software, u-control 2000, adapts individually to your requirements. And, the u-control is powerful, compact and fully compatible with Weidmüller’s I/O system u-remote. This article looks at what makes u-control the heart of your automation.

Programmable logic controllers (PLCs) are one of the main components of any automated system. A typical control system has inputs, outputs, controllers (i.e., PLCs), and some type of human interaction with the system, a human machine interface (HMI), for example.

Read More



Latest Articles

  • ABB’s Care and Modernization Services Breathe Second Life into Legacy Equipment

    April 3, 2024 The most comprehensive and sustainable options for extending product life In today’s world with environmental concerns top of mind, ABB offers sustainable options to extend equipment life through refurbishment and repair—which support a circular economy and reduce landfill footprints. In this context, ABB Canada’s Brampton facility is recognized for offering customized solutions… Read More…

  • A Guide to Industrial Ethernet (IE)

    April 2, 2024 Ethernet has become the backbone of industrial communication, enabling devices and systems to exchange data rapidly and reliably. This guide delves into Ethernet’s implementation in industrial settings, highlighting its advantages, protocols, frame structure, and data types to provide a solid foundation for professionals looking to leverage this technology. Understanding Industrial Ethernet At… Read More…