Purpose
Running the GUI
Using the GUI

Purpose

The purpose of this Graphical User Interface (GUI) is to allow the user to view an animation of the ball and beam system with the step response plot. This allows the user to see the correlation between the plot and the systems physical response.

The animation and GUI are based on the Ball & Beam:State-space example. This method was used because we can easily return the ball position and beam angle as well as their respective velocities. For more information on the system model please refer to the Ball & Beam: Modeling page.

Running the GUI

bbgui.m - contains the interface and controls.
bbfun.m - contains the GUI callback function.
bbfunode.m - contains the ode file necessary to run the non-linear simulation.

Once these files are copied into your MATLAB directory, simply enter the following command:

bbGUI

Using the GUI

The first group of controls contains the RUN, REPEAT, and RESET buttons. These controls perform most of the work in the GUI.

RUN - This button performs the simulation, plots the response in the upper-right axes and runs the animation in the lower-right axes.

REPEAT - The purpose of this control is to re-plot the response and re-run the animation. It uses the results from the previous simulation done by the RUN button. This is especially useful for the non-linear simulation, which can take some time to run.

RESET - This control clears the upper-right step response plot and sets the ball position and beam angle to zero in the lower-right plot. If a plot is not cleared the next run will be plotted on the same plot. This is useful if you want to see graphically the difference changing some values makes.

An example of the animation and response plot are shown below.

The next group of controls allows you to place the system's four poles wherever you want. This is how a full-state feedback controller is designed.

COMPLEX POLES - The two side-by-side editable text fields allow you to position poles in the imaginary plane. This first field represents the real part and should stay negative, a positive real pole will cause the system to become unstable. The second field contains the imaginary part. The +/- between them indicates that these are two poles in a complex conjugate pair. Making the real part more negative will decrease response time, while increasing the imaginary part will increase overshoot.

REAL POLES - The bottom two editable text fields contain the real poles which can be placed anywhere on he the real axis. These poles are usually placed far to the left so they do not interfere with the complex poles.

Feel free to move the poles around to see what happens!

This group of controls allow you to change the step input command.

STEP-SLIDER - The slider allows you to change the step input command. You can click on the arrows to move the slider, grab the the slider bar and move it, or click on the slider to change the step input. The current value of the step input is displayed in the upper portion of the box.

This group of controls contains checkboxes that allow the user to change various features of the GUI.

MANUAL ADVANCE - If this control is checked the user is able to advance the animation and plot one frame at a time. The frames are advanced by pressing any key on the keyboard. This function is useful is the animation moves to fast for the user and will allow the user to see everything that is going on.

PLOT SEPARATELY - By checking this box the step response plot is graphed in its entirety before the animation is run.

REFERENCE INPUT - This box is automatically checked when the GUI is run. By un-checking it the user removes the reference input term, Nbar, from the simulation. The reference input is used to correct steady-state errors common to full-state feedback systems.

NON-LINEAR SYSTEM - This checkbox allows the user to switch the model from the linear representation used throughout the tutorials to the non-linear representation of the system. Through the non-linear system the user may get a better idea of what actually happens in the system. For instance, the linear representation will allow the ball to move faster than is physically possible, when seen in the non-linear system the user will see that this actually is unstable.

REMEMBER, this GUI is intended to be an interactive learning tool that will allow the user to get a feeling for how some basic control techniques and ideas are represented in the real world. Therefore, the user is encouraged to PLAY around with this tool to enhance their understanding of controls.

Ball & Beam Examples

Modeling | PID | Root Locus | Frequency Response | State Space | Digital Control | Simulink

Animations

Bus Suspension | Inverted Pendulum | Pitch Controller | Ball & Beam

Tutorials

MATLAB Basics | MATLAB Modeling | PID | Root Locus | Frequency Response | State Space | Digital Control | Simulink Basics | Simulink Modeling | Examples | Animations