EUROelectronics is a machine builder that was asked to design a closed-loop hydraulic cylinder control system for a die-casting press machine. The high-speed press moves anywhere from 0 to 10 m/s and therefore requires a high-speed control system. To meet this challenge, we relied on the National Instruments LabVIEW FPGA Module and CompactRIO hardware. With the integrated FPGA on the CompactRIO controller, we could develop a system capable of low-level customization using commercially available tools. To meet the unique requirements of the application, we implemented a highly optimized encoder interface in the FPGA to measure the cylinder position while programming the system entirely in NI LabVIEW.
Essentially, the system controls the cylinder position to track the velocity and acceleration trajectory values the operator enters. The operator can control the cylinder movement through a proportional, integral, and derivative (PID) algorithm. The pressure sensor feedback is in the order of a few milliseconds, which was fully matched by the processing speed of CompactRIO.