Low-cost, easy-to-use electric motion

Use easy-to-use electric actuators: Digital I/O ensures pneumatics-like control, while IO-Link adds a third, mid-point position for new capabilities.

By Tim Sharkey February 5, 2021


Learning Objectives

  • Linear electric motion for positioning, indexing and clamping. 
  • Designs support more flexible control options. 
  • IO-Link supports predictive analytics. 

Motion controls that combine the simplicity of pneumatics with the benefits of electric automation are possible. New designs integrate spindle axes, toothed belt axes, mini slides, electric cylinders, and rotary actuators with an onboard-servo drive. Users commission two-position functionality via onboard push buttons without additional software. IO-Link control can be used for flexible, multi-position applications.

Electric motion for positioning, indexing, clamping

Applications for such electric actuators include positioning, indexing, clamping, feeding, and cut-to-length tasks where electric automation adds proficiencies and value. Low-cost simple electric motion can be used in machines and applications where compressed air is not practical or desired, such as medical lab equipment and operations in clean and sanitary environments. Ordering, inventory and replacement are streamlined as all of the components are integrated into one unit with a unique part number.

Applying pneumatics knowledge to electric motion delivers an equivalent ease of use. Low-cost and easy-to-commission electric motion bring opportunities for creative new motion-control implementations.

More flexible control options

Digital I/O (DIO) and IO-Link controls extend options. With DIO control, two available positions are home and a configurable end point. IO-Link offers flexible positioning along the axis, like a traditional electromechanical axis.

A programmable logic controller (PLC) set up for DIO control would be identical to programing a digital pneumatic valve with two digital outputs and two digital inputs. One digital output extends the axis and the other retracts it. The digital inputs indicate when the axis has reached the extended position or the retracted position, just like proximity switches would function on a pneumatic actuator. Design similarity to a pneumatic valve simplifies PLC programming, reduces the number of I/O typically required for servo-controlled motion, and speeds up installation of single and multiple units. Integrated position feedback eliminates the need for proximity sensors. Since the electronic components and modules are onboard the integrated drive these actuators are machine mountable. There is no external servo drive to mount in the control panel, which means minimal control panel overhead associated with these electric drives.

No software is required for teaching movement, maintaining the similarity between simple electric motion and pneumatics. Using drive-based push buttons helps ease commissioning. Some commissioning parameters include:

  • Speed for the extend (“out”) and retract (“in”) movement
  • Force of the axis in the “out” position
  • Setting the reference end position
  • Teaching the position for the start of force-controlled movement
  • Demo mode, which can be used to test the movements from the keypad.

Axes for simplified motion designs offer motion characteristics that ease commissioning for gentle cushion retraction and press-fitting and clamping functions. Simple electrical connection is accomplished via a M12 plug design with 4-pin power and 8-pin logic.

Flexible positioning, infinite variability

Simplified motion axes also can be used like a traditional electromechanical axis with infinitely variable positioning anywhere along the axis length when controlled with IO-Link. When used like this, the SMS axes offer a cost-effective alternative to traditional electric axes, including greater flexibility in material handling or applying electric motion in mobile applications.

Via IO-Link, technicians can remotely adjust movement parameters including infinitely variable positions and speeds, copy and backup functions for parameter transfer and read functions of essential process parameters.

IO-Link is the first worldwide standardized IO technology (IEC 61131-9) for communication with sensors and actuators. IO-Link devices are about the same cost as non-enabled sensors, which lowers the barrier to purchase. Three types of data available in IO-Link sensors and actuators.

  1. IO-Link devices carry event data that flags or notifies when critical events occur.
  2. IO-Link devices offer service data, including all the vital information about the unit such as manufacturer, model, and serial number. Service data also includes parameter values listed by the device and can be changed via the controller. Plug in a replacement device and the controller will automatically load parameters, saving time and lowering the chance of error.
  3. IO-Link devices collect condition data such as temperature, cycle counts, running distance, current, and more.

IO-Link supports predictive analytics

In a predictive analytic environment, the correct IO-Link device for condition monitoring is an ideal predictive analytic tool. There are a host of additional installation and commissioning advantages not covered here that make IO-Link fast, easy, and cost effective. I/O-Link supports Industry 4.0 and IIoT concepts of modularity and cloud-based reporting.

New electric actuator designs allow control engineers to choose between pneumatic or electric actuation for a machine and have a basic equivalency for cost and installation overhead. Since each actuation type offers its own motion and force profiles, as well as other operational factors, control engineers have broader options to apply to design challenges.

For simple linear and rotary motion capabilities, new electric motion designs represent an important opportunity for original equipment manufacturers.

Tim Sharkey is director of market management, for Festo Electric Automation in North America. Edited by Mark T. Hoske, content manager, Control Engineering, CFE Media and Technology, mhoske@cfemedia.com.

KEYWORDS: Automation implementation advice, motion control


Linear electric motion designs expand traditional pneumatic applications.

Author Bio: Tim Sharkey, Festo Electric Automation in North America