Smart hydraulic equipment is delivering IoT compatibility, better machine performance and precise control accuracy through Eaton’s embedded control systems.
Contributed by John Kimmel, Chief Engineer, Power and Motion Control Products, Eaton
Most industrial machines use a centralized PLC controller with input/output (I/O) modules. With this architecture, one PLC performs all required computing tasks for the entire machine.
Industrial machine end users are looking to equipment manufacturers to deliver better machine performance, state-of-the-art diagnostic capabilities and Internet of Things (IoT) compatibility. Equipment manufacturers are looking for faster commissioning and cost savings without sacrificing accuracy or power density.
Through the rise of intelligent components, faster communication protocols and automated decision making, smart hydraulic equipment is delivering all of this with more precise control accuracy than ever before.
Distributing the computing resources out of the PLC (programmable logic controller) control cabinet directly onto intelligent hydraulic components is a key alternative for equipment manufacturers and end users to attain these targets.
Distributed versus centralized control
Most industrial machines utilize a PLC controller. Traditional control systems use only a centralized controller with input/output (I/O) modules. With this architecture, one PLC performs all required computing tasks for the entire machine.
Take the example of a cylinder that needs to be repositioned. In a centralized control system, the PLC sends a spool position command to the valve, which in turn positions the spool to allow fluid to move to the cylinder. The PLC monitors the cylinder position and slowly commands the spool position back to neutral as the cylinder approaches the desired position.
In distributed control, dedicated motion control processors were added to the PLC cabinet to help offload the computing requirements from the PLC.
With this approach, the PLC needs a digital-to-analog converter to command the valve, and it needs the electronics necessary to read the cylinder position sensor. The PLC programmer has to design the sequencing for the machine and also develop and tune the cylinder position control loops for each axis. There was a time when machines were simple enough that all computing tasks could be managed by a single, centralized PLC. As complexity has increased, this has changed. Dedicated motion control processors emerged, which were added to the PLC cabinet to help offload the computing requirements from the PLC. With these motion control processors, the first generation of distributed control was born.
Going back to our cylinder example, the PLC now provides just the desired final cylinder position value to the motion control processors. The motion control processor takes care of commanding the spool position of the valve to achieve the desired cylinder position.
The PLC programmer no longer needs to design, implement and tune the position control loop — that task is now done on the motion control processors.
Now, manufacturers like Eaton are looking beyond the motion control cabinet, distributing machine control even further.
Relocating machine control
Component-level motion control is the next iteration of distributed control. By embedding sensors and intelligence into machine components, such as valves and cylinders, the control responsibilities for the machine are spread beyond the PLC cabinet to the individual components. Intelligent valves enable closed-loop control without the need for a separate motion control processor or for the PLC to close position control loops.
Eaton is calling its component-level motion control embedded control, in which sensors and intelligence are embedded directly into machine components, such as valves and cylinders. This takes the control responsibilities for the machine beyond the PLC cabinet to the individual components.
At Eaton, we call this embedded control, and we work with our customers to help them realize the benefits of moving control loops closer to the action. These benefits include reduced cabling, customizable operation, easier and faster commissioning, the availability of real-time diagnostics and cost savings.
Reduced cabling — Machines with embedded control require less cabling — sometimes even half as much — as compared to traditional control architecture. A sensor installed on a cylinder would typically require a cable to run all the way back to the PLC cabinet. With embedded control, the cable needs only run from the cylinder back to the intelligent valve.
Customizable operation — Embedded control allows machines to run custom software applications that have been tailored precisely to the machine on which they are installed. Every machine’s duty cycle can vary, and with embedded control the duty cycle sequencing can be done at the component level. This simplifies the requirements of the central PLC.
Easier and faster commissioning — Components like Eaton’s AxisPro proportional valve allow machine builders to program one axis at a time, without needing the complete PLC code running at once. Configuration software enables engineers to quickly program the valve using parameter-based tuning. With no specific programming language expertise required, the software allows the user to easily input key settings like relief pressure, hose volumes, cylinder stroke, and cap and rod diameters to quickly and easily tune the valve to meet specifications. The intuitive graphical software makes the process easier and faster than adjusting parameters one by one. Setting up the controls so that the machine behaves as intended no longer needs to be the most difficult part of commissioning a new machine.
Real-time diagnostics and IoT — Onboard sensors and digital communication in embedded controls provide real-time diagnostic information to end users, providing vital machine health monitoring that helps maximize uptime. By monitoring for key process variables or even custom-set faults, component-level intelligence can improve throughput and quality, and can alert maintenance staff when essential repairs are needed.
Cost savings — All of the benefits highlighted here add up to cost savings in building and operating the machine. Faster commissioning gets the machine up and running quicker, and real-time diagnostics can help end users perform maintenance sooner, both of which help maximize machine uptime and reduce operating costs. Reducing cabling and eliminating the need for dedicated motion control processors lowers costs for the machine build.
In industrial machinery, complexity is increasing and end users are looking for fast and accurate motion control solutions without the added complexity during commissioning. Eaton has solved this by further distributing the control logic to the component level. The AxisPro valve and the recently released configuration software, Pro-FX Configure 2.0, are making increased precision and faster commissioning the norm in the industry. DW
Eaton
www.eaton.com
Filed Under: Industry 40, IoT, Valves & Manifolds
