Design and Validation of Digital Controllers for Hydraulics Systems

In order to increase the flexibility and performance of hydraulically actuated machines there is a demand for more intelligent controllers. This leads to a rapid increase in complexity of the control systems. To manage the complexity and to ensure reliability of these systems, adequate software development methods are needed. In this work, we propose a methodology for structured design of digital hydraulics controllers in Simulink/Stateflow. A model architecture based on mode-automata is introduced to separate control and data processing. Furthermore, design by contract is advocated as a method for system development. The contracts can be used to mathematically reason about correctness of Simulink/Stateflow models and thereby increase the safety and reliability of the developed systems. The usefulness of these concepts are demonstrated on a larger case study from the area of digital hydraulics.