Digital hydraulics systems contain advanced and intelligent control algorithms, where reliability is an important issue. The complexity of control code is a problem in Digital Hydraulic systems and the problem becomes even more severe when new control features are added. Within the ITCEE-project we are relying on formal software construction techniques to assist in developing reliable complex algorithms. We have developed a method for structuring control systems using mode-automata and Simulink/Stateflow, where control logic is separated from signal processing and control computation. Furthermore, a development method involving design by contract applied on the Simulink models has been developed. The method provides a way of verifying the validity of the system in a stepwise manner. In order to provide an alternative way for finding contract violations in complex control systems we have investigated optimization based search methods
In cooperation with the IHA-lab at Tampere University of Technology, we have set up the requirements for the digital hydraulics system and created a structured specification of the system using our methodology. The quality of the Simulink models are being assessed to better evaluate the performance of the development methods.