Smarter Monitoring, Diagnostics, and Maintenance
In addition to returning real-time position data to the user, the network can monitor and report temperature, current, speed, voltage, and other variables, which enable advanced condition monitoring, diagnostics, and error handling. Feedback can arrive up to 10 times per second, as the actuator constantly tests itself. If it detects a problem, such as surpassing a temperature threshold, the actuator can stop mid-stroke or finish its programmed move, either fully retracted or extended, and send an error flag to the computer — all in fractions of a second. Following are some of the variables that can now be efficiently monitored:
- Current. Current monitoring is a critical safety feature that shuts down the actuator on overload and eliminates the need for the traditional noisy mechanical clutch.
- Voltage. Continuous monitoring of voltage protects the actuator by preventing motion if it detects it is operating in an environment outside of the acceptable range.
- Temperature. Internal temperature is monitored and, if outside the acceptable temperature range, the actuator is shut down after extending or retracting stroke. Built-in temperature compensation allows the actuator to push the rated load at lower temperatures without nuisance tripping.
- Load. Trip points can be calibrated at assembly to ensure repeatable overload trip points independent of component and assembly variations. This produces repeatable performance, and relieves the end user of the need to recalibrate in the field.
With integrated electronics, such functionality is available to the end user on demand, and via the network, it is potentially sharable in support of external troubleshooting. Once problems are identified, the plug-and-play capability gained by integrated standards simplifies repair and replacement. Where replacing a problematic hydraulic actuator might require a service call from the manufacturer for hours or even days of disassembly, reassembly, system bleeding, and testing, a smart actuator can be replaced in less than 20 minutes.
The ability to monitor themselves not only makes smart actuators easier to operate and maintain, their complex electronics also present a level of vulnerability that make this monitoring essential. Ensuring reliable operation requires designing smart actuators to meet industry standards for protection from ingress by solid objects and liquids, extreme temperatures, operational shock, vibration, corrosion, voltage variation, and electromagnetic interference.
Not every actuator must be protected from all environmental assaults, and each OEM requires its own profile of standards. Likewise, vendors have developed their own sets of procedures for meeting those standards. A major advantage of actuators that embed previously external devices is that compliance with the appropriate standards is done at the factory and need not be repeated once the systems are installed.
Putting Smart Actuators to Work
Smart actuators are finding their way into numerous industries (Figure 3). Following are a few examples of markets that are already going “smart.”
Factory Automation: A provider of customized industrial automation systems for the textile industry has used the low-level switching capability provided by smart actuators to eliminate costly external relays. This made it easier to provide customers with a more compact automation system. Built-in potentiometers also provide them crucial position information.
Robotics: Designers of an automated valet parking system most likely could not have realized their solution without smart actuators. Patrons signal that they are ready to pick up their cars with their mobile phones, and an actuator-driven, robotic assembly delivers the car to them.
Material Handling: Manufacturers of logistics trains use smart actuators to help increase load capacity, regulate operations, and reduce maintenance. Low-level switching, verified positioning, and end of stroke shut off are among the features frequently applied in material handling.
Construction and Agricultural Equipment: A startup combine manufacturer used J1939 networking capability to enter its market with an attractive product. It could offer integrated control of actuators on five axes, including the rock trap door, gate latch, ladder, grain tank, and auger.
Solar energy: To store maximum energy, numerous solar panels must move in sync to follow the sun. One solar panel manufacturer accomplished this with smart actuators that fully leverage the embedded J1939 CAN bus compatibility.
Waste disposal: A garbage handling system manufacturer relies on low-level switching to eliminate the need for expensive relays, and it uses integrated end-of-stroke signals to remove the cost and complexity of external limit switches. Integrating the electronics and routing the cables to a common plug also eliminated the need for both five meters of external cabling and creating specialized wiring harnesses to accommodate it.
The Next Generation
Given their computational and communications capabilities, smart actuators will likely be increasingly integrated with other similarly enhanced sensors, data acquisition devices, and production equipment, as well as other actuators. Today they are fully ready to participate in the emerging industrial internet of things (IIoT), where every device not only has intelligence and networking capability but also an internet address and the ability to share and subscribe to information sources. And the IIoT is part of an even broader industrial revolution, in which computational, communications, and physical domains increasingly interact without human command. Known as cyber-physical systems or, sometimes, just Industry 4.0, this promises new levels of efficiency, economy, and safety.
This article was written by Anders Karlsson and Travis Gilmer, Product Line Specialists for Industrial Linear Actuators at Thomson Industries, Inc., Radford, VA. For more information, Click Here .