6 Steps to an On-off Controller Using Stateflow
By Sandeep Hiremath, MathWorks
On-off (also known as bang-bang) is a simple control method frequently used in systems that do not need high performance or accuracy, such as water heaters, air conditioners, and refrigerators.
In just 6 steps you can build an on-off controller for your Simulink® model using Stateflow®.
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Add a Chart block to your Simulink model. You’ll find this block in the Stateflow library.
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Open the chart to start building the state machine for the controller. An on-off controller has only two states, or modes of operation (e.g., on-off, up-down, or left-right). Add two states to the chart using the State tool.
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Add the entry actions to the states and then draw transition lines between the states. Label the transition lines to define the logic (conditions) that make the system change from state to state. The objective in this case is to switch the output (out) between two values based on the control input (inp) value.
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Update your Simulink model by resolving (defining) inp and out in the Symbol Wizard. Simulink will then add input and output ports to the Stateflow chart you’ve created.
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Set up the Simulink model by connecting the blocks as shown. Use Dashboard blocks to add graphical tools and displays for visualizing simulation data.
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Run the model and observe the simulation output of the controller in the Dashboard Scope. Set the Stateflow animation speed to Slow to visualize the behavior of the state machine
Published 2017
