1 Quality Analysis of Simulink Models Marta Pląska 1 , Mikko Huova 2 , Marina Waldén 1 , Kaisa Sere 1 , Matti Linjama 2 1 Department of Information Technology Åbo Akademi University Joukahaisenkatu 3-5 FIN-20520 Turku {marta.plaska, marina.walden, kaisa.sere}@abo.fi 2 Department of Intelligent Hydraulics and Automation Tampere University of Technology P.O. Box 589 FIN-33101 Tampere {mikko.huova, matti.linjama}@tut.fi Abstract In this paper we present a measurement framework for complex control systems developed in Simulink environment. Quality analysis of a digital hydraulics control system is done for the purpose of its evaluation and improvement. We concentrate on the assessment of quality of the development process and the created software in perspective of lightweight formal methods. 1 Introduction Continuous software improvement is observable everywhere nowadays. It is also a major goal for most software organizations. The evaluation of quality of produced software is considered as a main activity towards achieving high quality products. Our goal for performing a measurement program is to monitor and evaluate the quality of control system software and its development process. Most of the developers have some intuition about the quality of software they produced [Jor99]. However, to genuinely determine the quality and obtain its complete picture, measurement activities and appropriate metrics are necessary. The analysis, which takes place after data collection and gathering measurement results, is the final outcome of the examination. It portrays the quality features of the system, by assigning values to the tested characteristics in question, thus giving them certain meaning. Measuring software quality is very complex, because it consists of evaluating software products, processes and resources, each of which is composite as well. Assembling these aspects of quality allows us to get a comprehensive view on the developed system. Assessing the quality of control software systems, like the digital hydraulics ones, is challenging, as it is multidimensional and algorithmically complex. Digital hydraulic systems are an alternative in the fluid power technology, replacing high-cost analogue valves with simple and easy to manufacture on/off-type valves. Digital hydraulic valves