AbstractRijkswaterstaat is planning to renew and renovate many of the existing tunnels in the Netherlands in the upcoming years. A national tunnel standard, the LTS, has been formed to achieve standardization between those tunnels, both in the physical components and the control structure. However, practice has proven that the realization of the tunnels still differs due to local circumstances or choices made by third parties. These differences in the tunnel realizations also lead to differences in the supervisory controller of the tunnel. Therefore, a new supervisory controller needs to be designed and created for each new tunnel or tunnel renovation.
This design and creation process currently requires a lot of time and money, which is why research is started to find a better alternative. The main objective of this project is to show that the use of a formal design method, called synthesis-based engineering (SBE), can decrease the time-to-market of the tunnel supervisory controller while also improving the quality of this supervisory controller. The second objective is to analyze the structure of the components in the supervisory controller. Such a structure analysis gives a clear overview of the tunnel supervisory controller, and gives insight into the modularity and hierarchy of tunnel supervisory controller components. The Koning Willem-Alexandertunnel is used as a case study by recreating its supervisory controller using the SBE method, and performing a structure analysis using the dependency structure matrix (DSM) technique.
The SBE method adds two mains benefits compared to the currently used V-model method. First, a modeling step is added in the design process in which both the uncontrolled behavior and the requirements of the supervisory controller are modeled. These models are then used to synthesize the supervisory controller of the tunnel. This synthesis step is an automated operation instead of a manual operation, which reduces realization time and also eliminates manual errors. The second advantage of the SBE method is that supervisory controller simulations can be performed to find errors at an early stage.
The DSM technique used for the structure analyses visualizes the structure of the supervisory controller components in a square table. Component dependencies are indicated in this table by coloring the boxes corresponding to two related components grey. Structuring algorithms are then used to find clusters of components that have many relations with each other.
The plant models and requirement models created during this project are mainly based on existing design documents of the KWA tunnel, and where necessary supported by the LTS. In case of unclear system behavior or unclear requirements RWS experts are asked questions to ensure the correct behavior and requirements are modeled.
A monolithic supervisory controller is synthesized using the plant and requirement models. The controlled behavior of the supervisory controller is validated using simulations to find incorrect behavior. Furthermore, RWS experts have analyzed the behavior in the simulations to give more feedback on the controlled behavior.
In the structure analyses performed in this project, the component dependencies are based on control relations between plant components. This means that two plant components are related if there exists a requirement using both of these plant components. An analysis of the clusters in the clustered DSM thus gives insight into the modularity and hierarchy of the tunnel supervisory controller components.
This project shows that SBE is a suitable design method to create a tunnel supervisory controller. The requirement documentation can in many situations be improved, as some requirements are defined ambiguously, contradicting, or completely missing. The use of simulations proves to be a useful tool to detect errors in the supervisory controller in an early design stage. Furthermore, simulations can be used by RWS and third parties to get a clear image of the tunnel system and its behavior.
|Date of Award||31 Oct 2018|
|Sponsors||RIKZ, Rijkswaterstaat Corporate Dienst|
|Supervisor||J.M. (Asia) van de Mortel-Fronczak (Supervisor 1), Jacobus E. (Koos) Rooda (Supervisor 1), Martijn A. Goorden (Supervisor 1), L.F.P. (Pascal) Etman (Supervisor 1) & Patrick Maessen (Supervisor 1)|