Low Loss Hydraulic Power Transmission for Wind Turbines
Edinburgh staff have pioneered the design of novel digitally-controlled hydraulic transmission systems  culminating for the design and production of high efficiency hydraulic gearboxes, now owned by spin-out company Artemis Intelligent Power Ltd. This innovation comprises the Digital Displacement (DD®) patented technology  with current application in wind turbine systems, and vehicle drives.
Conventional mechanical gearboxes are the critical limitation on the up-scaling of large wind turbines for on- and more especially off-shore application. Due to mechanical failure, the 50 tonne mechanical gearbox can be replaced by a 17 tonne DD ® design! Salter and Rampen pioneered the commercial adoption of this novel hydraulic transmission technology by spinning out Artemis which holds a portfolio of 87 patents, winning strategic investment of over £3.5M from Scottish Enterprise, Energy Saving Trust, Technology Strategy Board and Department for Energy and Climate Change, etc.
Artemis have refined their DD® technology in partnership - with the oil major Conoco, with two Tier One automotive suppliers. "As Chairman at Artemis I can verify that the early Edinburgh research to develop digitally controlled hydraulic pumps and the design, technical assessment and subsequent refinement of the initial small scale prototypes was instrumental in proving the concept that ultimately became the patented Digital Displacement® technology. This highly innovative Edinburgh research laid the secure foundation and enabled the growth of Artemis into the significant 50 person company that it is today and also to securing the major inwards investment from Mitsubishi".
In December 2010 Artemis was acquired by Mitsubishi Heavy Industries as part of a £100M Scottish inwards investment. "As Chairman of Mitsubishi Power Systems, I can confirm that the highly innovative Artemis hydraulic transmission technology was the key attraction for our selecting Central Scotland for this significant investment and deciding to establishing our new Centre for Advanced Technology close to this company".
The hydraulic transmission has been extended for application to a hybrid car in 2008, which achieved a 50% reduction of urban fuel consumption and CO2 emissions - with no loss in performance. Sauer Danfoss, a leading manufacturer of off-road mobile hydraulics, now hold the rights for this deployment in materials handling and larger vehicles with pilot installations now under test.
Further information on Artemis Intelligent Power is available at: http://www.artemisip.com.
 Salter, S.H., Taylor J.R.M. and Caldwell, N.J., "Power Conversion Mechanisms for Wave Energy", Proceedings Institution of Mechanical Engineers, Part M: Journal of Engineering for the Marine Environment, Vol. 216, pp. 1-27, June 2002. DOI:10.1243/147509002320382103.
 Rampen, W., Ehsan M. and Salter, S.H., "Modeling of digital-displacement pump-motors and their application as hydraulic drives for nonuniform loads", Transactions of American Society Mechanical Engineers (ASME) Journal of Dynamic Systems, Measurement and Control, Vol. 122, No. 1, pp. 210-215, March 2000. DOI:10.1115/1.482444.