The fusion of the physical world of production and the virtual world of information technology into Industry 4.0 is becoming increasingly important. The requirements are clearly defined: decentralised intelligence and autonomous behaviour; open communication standards; quick networkability; and context integration in real time. When combined with digital control technology and open communication, hydraulics meets these requirements. It also brings the physical advantages of high power density, modular design and robustness to networked solutions.
The crucial step for integrating hydraulics into Industry 4.0 has already been taken: connecting hydraulic actuators to digital control electronics to shift functions to the software. Typical controllers such as for the transition from path control to force control or for synchronism, for example in presses, come pre-programmed. With this decentralised intelligence, hydraulic drives can behave autonomously and adapt to changing process parameters.
Software for quick networking
Bosch Rexroth has been one of the foremost driving forces behind this development. “We have predefined the default hydraulic functions in our best-in-class controllers so the user can configure them directly,” explains Markus Rukaber, head of product management in machinery applications and engineering. “This supports the user when starting up hydraulic axes. It allows hydraulic solutions to be quickly networked and optimally calibrated online to meet individual requirements.”
Drives with decentralised intelligence
Variable speed pump drives open up additional options in the area of decentralised intelligence. They combine the benefits of electrical engineering with hydraulics. The drives in Rexroth’s Sytronix family generate flow as needed and reduce power consumption in the hydraulics by up to 80% compared to conventional solutions. Depending on the application, the Sytronix can take over the positioning of the cylinder directly. This reduces system costs, increases flexibility and simplifies startup.
Rexroth takes it one step further with self-sustaining linear axes. These ready-made cylinder assemblies come with their own fluid circuit with variable speed pump. The cylinder generates linear movements without wear and is protected from overloading. Self-sustaining axes are installed like electrical drives. A cable just has to be connected to the power supply and the axis connected to the control system. “These axes have all of the functions of purely electrical drives,” says Rukaber. “They also offer all of the benefits of hydraulics, including wear-free, high power density.”
Basic requirements for open standards
Experts agree Industry 4.0 demands standardised communication protocols and programming languages. Established fieldbus systems already connect technologies such as electric drives, hydraulics and pneumatics with the control system. Numerous machine manufacturers have now taken this one step further and switched to real-time Ethernet protocols such as Sercos, Ethernet IP and Profinet.
“Rexroth not only supports bus connection, but also real-time connection to hydraulics through multi-Ethernet interfaces for the variable speed pump drives and motion controller”, stresses Rukaber. The multi-Ethernet interfaces by Rexroth support current real-time protocols such as Sercos, EtherCAT, Ethernet IP, Profinet RT and Varan on one piece of hardware. Control systems and higher systems thus have total access to the hydraulics and allow system integration, regardless of manufacturer.
Remote diagnostics and condition monitoring
Connecting hydraulics via Ethernet unlocks remote diagnostics and remote maintenance options. All control electronics are uniquely identifiable. With the proper authorisation, technicians can query data online, regardless of their physical location or change parameters.
Decentralised intelligence also opens up the broad field of condition monitoring. The electronics analyse sensor signals and the software determines the current operating status of the hydraulic system. If the measured values exceed defined tolerances, the system warns of reaching critical states. This allows maintenance technicians to take action before the machine shuts down.
Drive physics neutralised
With decentralised intelligence and open standards, the software for hydraulic systems detects changing context and automatically adjusts motion sequences. Drive physics no longer plays a role for the higher control system. It does not matter whether the motion is electrical, electromechanical or hydraulic. This means, for example, that hydraulic press stations can read RFID product data and flexibly adjust the press capacity to the individual workpieces without the need for an operator or higher control system to intervene.
Hydraulics can match electro-mechanics in terms of automation and can meet the requirements of Industry 4.0. In addition, hydraulics has unique physical advantages. “When combined with electronics, software and open standards, hydraulics integrates perfectly into today’s and tomorrow’s Industry 4.0 concepts and brings to the table its unique physical advantages,” concludes Rubaker.
Bosch Rexroth has a 50% joint venture with Hytec in South Africa.
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