“Smart systems create value.”

“Smart systems create value.”
Marginal Column
Prof. Dr. Hubertus Murrenhoff

Since October 1994, Prof. Hubertus Murrenhoff has been director of the Institute for Fluid Power Drives and Controls (IFAS) and holder of the chair of the same name at RWTH Aachen University. At the 11th IFK, which will be held in Aachen from March 19 to 21, 2018, the issues discussed here will be the focus under the motto “Fluid Power Networks”.

Copyright Photo: IFAS


July 2017


Intelligence and open interfaces are the crucial requirements for future hydraulic solutions. Professor Hubertus Murrenhoff from the IFAS at RWTH Aachen knows which steps are necessary.

With the arrival of Industry 4.0, networking is becoming increasingly important. Is hydraulics ready for digitalization?

Yes, it is. We have field bus as a standard, sensors are becoming increasingly smart, and this makes interaction possible. Now, it’s time to take components to a higher level and use smart software to network all modules into integrated control loops. The key benefits of smart solutions are intensive interaction and distinct machine intelligence.

Is that what you mean by “intelligent hydraulics”?

Yes. We’ve been misusing the term “intelligent” for too long. Intelligence doesn’t come from the field bus and you can’t achieve it by a proliferation of sensors. When I talk about intelligent hydraulics, I mean a smart overall system, in which every component knows what it is and what it does. A system in which all modules or subscribers speak the same language and can therefore communicate with one another without barriers. In tomorrow’s hydraulic systems, there will no longer be any mute components.

What is important when it comes to distilling usable information from the flood of data?

Firstly, we need to see the wealth of data as a gift and not as a threat. Ultimately, we have the huge amount of raw data well under control. Memory density and computing speeds are simply inexhaustible these days. However, we do need the right software, with algorithms that can analyze findings, distill usable information, and generate genuine benefits. For example, the actuator 4.0 in the machine tool then knows before a new workpiece rolls up what condition it is in, what operations are necessary, and what will happen to it next. The hydraulics adapt proactively to the new situation and allow a product change at very high speed. In 15 to 20 years, all machines and vehicles on a construction site 4.0 will know what material has to be removed and where, the sequence of operations, and what has to be constructed where – and will synchronize themselves autonomously. Depending on the task to be performed, the hydraulics will have adjusted to the requirements in advance.

Smart hydraulics needs sensors. Is what we are familiar with today enough?

Acquiring raw data is not the challenge, rather heterogeneity. In the future, we will not only have the familiar hard facts such as pressure, flow rate or temperature, we will also need to be able to analyze and identify images, videos, or noise spectra. Human intuition can do this, but machine intelligence needs some far-reaching development steps. We need to succeed in using machine intelligence to identify patterns in unstructured data and draw conclusions. At best, we are part way through the development process and still have a long way to go.

Condition monitoring and predictive maintenance are currently the big focus areas in the industrial IoT. Is that justified?

Yes, because they are two very tangible aspects. We just have to make sure that the achievements in smart networking are not simply reduced to these two things. Having said that, preventive maintenance is a good way to get customers enthusiastic about the process, because they can quickly recognize that additional costs are rapidly amortized during the life cycle. Once they are enthusiastic, we can create a positive climate for other applications. For example, the actuator 4.0 or construction site 4.0 I mentioned before.

How important do you think 3D printing is?

3D printing creates a huge amount of freedom and will revolutionize some industries. This makes it a key technology for the future. For materials with low requirements, such as plastics, 3D printing is already a standard technology and machines are available for less than EUR 1,000. Of course, the price for high-precision complex plastics – such as those required for seals and membranes – can rise by several powers of ten. Even high-performance materials such as steel with a fault-free structure in aerospace engineering can be produced competitively using 3D printing and laser methods. They are used for structural components and in turbine production. Looking somewhat into the future, 3D concrete printing on the construction site 4.0 will also be feasible. At Bauma 2016, we won the innovation prize in the R & D category with this idea.

Will new hydraulic valve materials play a big role in the future?

Definitely. We are just beginning an AiF research project, in which compensated ceramic flat slide valves will make drip-tight valves possible at standard pressures of 300 bar absolute. Composite materials could also play an increasingly important role in the future. For example, hydraulic accumulators with CFK reinforcement can now be produced and are state of the art.

Looking at efficiency, it is impossible to avoid the issues of energy on demand and energy storage over a machine cycle. What developments are you anticipating?

The answer to this is a crucial one for readers to be aware of. Nothing is better suited to absorbing large quantities of energy in a very short time and discharging that energy again at a later stage than a robust and economical hydraulic accumulator. This is a competitive advantage over electromechanical solutions, a fact that is given far too little emphasis. With the VIP STEAM project, we have been able to use the example of an 18-ton wheeled excavator to impressively demonstrate that an integrated solution incorporating the diesel engine has massive potential. With just the prototype machine, an efficiency advantage of 30 percent over a standard LS system was demonstrated in field tests, with reduced cycle times. Once again, the only way to take advantage of the potential is with smart solutions that analyze the overall system and offer integrated optimization.