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Combined digital hydraulic innovations for improved energy efficiency

One performance measure in hydraulic motion control is efficiency, or in other words, a minimal loss factor. In his dissertation, Matti Karvonen studies the energy-saving potential in multi-actuator applications by means of digital hydraulic innovations.

A dream of the lossless hydraulics has been a driving force behind the development of digital hydraulics. Pumps and valves are key components in hydraulic systems, and by means of digitalization, they can be further improved.

A digital valve system – a DVS, developed some years ago at TUT, is programmable by its nature and thus overall efficient control is possible if the supply unit, a pump, may co-operate accordingly.

An optimal supply unit generates exactly the required power for multiple actuators and also deals with the recuperation. Also, in case of pumps, digitalization is the way to improvements. A digital hydraulic power management system – a DHPMS – or more precisely the DHPMS, as it is currently the only one of its kind in the world, has been developed at TUT a couple years ago.

“A DVS and the DHPMS bring benefits in themselves, but when put together, the whole truly is greater than the sum of its parts. By combining these two optimized pieces of technology together, it is possible to ensure universally high efficiency of hydraulic circuit design. However, controlling such a combination is not trivial. That is why we needed to examine the holistic control system design,” Matti Karvonen explains.

Karvonen’s dissertation examines the capability of the DHPMS to work as an optimal sink/source of hydraulic power together with optimal digital valves. The test setup emulates realistic application and also accounts for energy efficiency. The origin of losses is inspected and analysed, and solutions are presented. The potential of the technological advancements is proven through simulations and measurements.

The results show that the digitalization works, but in order to gain maximum benefits made feasible by the DHPMS and a DVS, both these are also required. By applying digital hydraulic innovations in a two-degree-of-freedom test system, up to 40% in energy savings can be achieved compared to the current state-of-the-art system. Similar results were achieved both through simulations and measurements.

Public defence of a doctoral dissertation on Thursday, 26 May

M.Sc. (Tech.) Matti Karvonen’s doctoral dissertation in the field of automation and systems engineering entitled ‘Energy Efficient Digital Hydraulic Power Management of a Multi-Actuator System’ will be publicly defended at the Faculty of Engineering Sciences of Tampere University of Technology (TUT) in lecture room K1702 in the Konetalo building at 12 noon on Thursday, 26 May 2016.

The opponents will be Professor Torben Andersen (Aalborg University, Denmark) and DTech Timo Käppi (John Deere Forestry Oy, Tampere). Professor Seppo Tikkanen from the Department of Intelligent Hydraulics and Automation at TUT will act as the Chairman.

The dissertation is available online at:

Matti Karvonen (31) has recently worked as a teacher of natural sciences, mathematics and IT.

News submitted by: Tiina Leivo
Keywords: science and research, digital hydraulics, power management, energy efficiency