Interactive simulation of a liquid tank: Matlab class, source code detail

Antonio Sala, UPV

Difficulty: **** ,       Relevance: ,      Duration: 14:56

*Enlace a Spanish version

Summary:

This video details the Matlab code for interactive animation (responding to keyboard input) of filling or emptying a liquid storage tank. This animation was used in previously piublished introductory motivational videos for systems engineering ([tanksist] and [modelsintroEN] videos).

Here we discuss line by line the class (classdef) that handles the animation data and has the following methods:

• constructor, to initialize the data;

• “frame” drawing for animation, 20 times per second;

• simulation of the differential equation $\frac{dh}{dt}=\frac{1}{S}(u-\kappa \sqrt{h})$, approximating by Euler’s method. If the sampling period (frame to frame, 1/20 s) were larger, another numerical integration method might be needed, such as ode45. This method is the most conceptually important from a systems theory point of view (numerical integration).

• Response to ‘key press’ event to perform different actions depending on the key that the user had actually pressed. The actions are raising/lowering inlet flow or stopping the simulation.

Last, the code of a script that is in charge of creating the animation, simulating for a certain time and presenting input and output plots once the simulation is finished is, too, detailed.

*Link to my [ whole collection] of videos in English. Link to larger [ Colección completa] in Spanish.