Water Tank Fault Injection

Overview

This example shows a digital twin (DT) with fault injection (FI). A live DT receives simulated faults from the environment. The faults are part of the DT configuration and can be changed for new instances of the DT.

This co-simulation based DT uses a water tank case study. The co-simulation consists of a tank and a controller, and its goal is to keep the water level in the tank between Level-1 and Level-2. Faults are injected into the output of the water tank controller (watertankcontroller-c.fmu) from 12 to 20 time units. The faults close the tank outlet for a period of time, and the water level rises above the desired level (Level-2).

Example Diagram

Water Tank System

Example Structure

Water Tank Structure

Digital Twin Configuration

This example uses two models and one tool:

Asset Type	Names of Assets	Visibility	Reuse in Other Examples
Models	watertankcontroller-c.fmu	Private	Yes
	singlewatertank-20sim.fmu	Private	Yes
Tool	maestro-4.1.0-jar-with-dependencies.jar	Common	Yes

The DT is executed with two configuration files, multimodelFI.json and simulation-config.json. Edit them to customise the DT.

Note

The faults are defined in /workspace/examples/data/water_tank_FI/input/wt_fault.xml.

Lifecycle Phases

Lifecycle Phase	Completed Tasks
Create	Installs Java Development Kit for Maestro tool
Execute	Produces and stores output in data/water_tank_FI/output directory
Clean	Clears run logs and intermediate co-simulation files

Run the example

To run the example, change to the example directory.

1	`cd /workspace/examples/digital_twins/water_tank_FI`

If required, make the lifecycle scripts executable, for example:

1	`chmod +x lifecycle/create`

Then run the following scripts.

Create

Installs Open Java Development Kit 21 and the pandas and matplotlib Python packages from the Ubuntu repositories (python3-pandas and python3-matplotlib).

1	`lifecycle/create`

Execute

Runs the co-simulation and writes the outputs.csv file to /workspace/examples/data/water_tank_FI/output.

1	`lifecycle/execute`

Analyze phase

Processes the co-simulation output and saves a plot in /workspace/examples/data/water_tank_FI/output/plots/.

1	`lifecycle/analyze`

Examine the results

The results are in the /workspace/examples/data/water_tank_FI/output directory.

The run logs are in /workspace/examples/digital_twins/water_tank_FI.

Terminate phase

Removes the temporary files.

1	`lifecycle/terminate`

References

More details on this case study are in the paper:

M. Frasheri, C. Thule, H. D. Macedo, K. Lausdahl, P. G. Larsen and
L. Esterle, "Fault Injecting Co-simulations for Safety,"
2021 5th International Conference on System Reliability and Safety (ICSRS),
Palermo, Italy, 2021.

The fault injection plugin extends the Maestro co-orchestration engine. It can replace the inputs and outputs of FMUs in an FMI-based co-simulation with tampered values. More details on the plugin are in the fault injection Git repository. The same repository holds the source code for this example in its example directory.