Servos are the go-to technology for robotics and servo systems play an important role in operating the supporting equipment around robots for loading and unloading parts and products. The term “motion control” for industrial automation equipment is usually applied to the use of electrical servo motors, drives, and controllers for operating various axes of robot motion. However, servo systems are also fundamental for monitoring, computing, and controlling activities of conveyors, grippers, and other handling equipment.

Servo motors convert electrical power into precisely controlled motion. These motors are operated by a drive that is commanded by a controller. Each of these functions can be performed with an individual device (Figure 1) or are sometimes combined. Designers must determine the application requirements for:

  • Velocity and accel/decel

  • Accuracy of positioning and speed

  • Number of related axes

  • Force

  • Duty cycle

  • Higher-level automation and integration

Users have a few choices for automation. They can use a dedicated servo controller with built-in industrial protocols like EtherNet/IP, PROFINET, or others. Another option is a programmable logic controller (PLC) that supports specific motion control instructions. For applications with complex integration requirements and/or many degrees of motion, using a motion-capable PLC can provide the best communication and overall coordination.

Many users find that choosing servo hardware from a single vendor provides the lowest risk and highest performance. This approach provides a scalable set of options to address any application (Figure 2).

A common application for servo motion incorporates box-forming machines, along with product container infeed conveyors that supply a robot and more conveyors and packaging equipment downstream of a robot. Each of these elements must be highly coordinated with the others to supply the boxes and products to the robot at the right speed so the cases can be filled and then discharged.

Figure 2. Emerson’s PACMotion family uses controllers installed in the PLC backplane to provide tight integration. It can reliably scale up to as many as 40 axes without performance degradation.

Designers can take advantage of advanced motion capabilities to perform smooth product handling and to speed positioning while avoiding product tumbling or slipping. For production lines that handle different product sizes, some servo systems offer changeable camming profiles, allowing the system to quickly perform changeovers for multiple product sizes. Some of these capabilities are only available in full-featured servo product lines. Finally, the most capable servo systems provide enhanced analytics and diagnostic information to help users optimize operation and maximize uptime.

Servos are used onboard robotics for their power, speed, and precision. For the same reasons, servos are used extensively to perform the equipment-related motion control activities associated with a robot. While it is true that servo motion control adds a degree of complexity and expense to any project, these systems are reliable and efficient in service and they deliver the required high level of performance.

Due to the great degree of integration commonly required with servo systems and the growing need for operational and diagnostic data, designers should consider the communications and interoperability capabilities of servo systems when selecting the platform. Choosing servo motion control technologies from a portfolio of industrial products can reduce risk and ensure best performance.

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Tech Briefs Magazine

This article first appeared in the July, 2021 issue of Tech Briefs Magazine.

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