Laboratory Experiments > Ball and Beam > Brief Description

BB50 Ball and Beam

The laboratory experimental setup "Ball and Beam" contains the technical realization of a nonlinear plant together with an actuator and a digital controller using observer based state feedback.

The nonlinear plant is represented by a ball laying on a beam with an adjustable angle. The ball can roll upon the beam within a distance of 1m. By a toothed belt, a toothed wheel and a clutch mounted on the shaft of a DC-motor the beam can be driven such that the ball is stabilized at a preassigned position. The stabilization of the ball is accomplished by a digital controller. Based on measurements, the controller generates a suitable signal, which controls the DC-motor by an electronic servo amplifier. The measurements are the angle of the beam obtained by an incremental encoder and the ball position obtained by a CCD-camera. The system is ready to operate after connecting to the electronic actuator. All the moving parts are covered by transparent plexiglass.
In a standard version the experimental setup BB50 includes the mechanical setup as well as a 19" casing which contains the servo amplifier for the DC-motor, the signal adaption unit as well as power supplies. The documentation of the laboratory setup Ball and Beam includes sections for assembly and start-up, the technical data, the theoretical background and the mathematical model of the plant. The guidelines for the practical course with solutions are in preparation.

The Option 50-02 extends the standard version of the BB50 by the adapter card MF634 ready to plug in a PC with PCIe slot and a Windows controller program. The card provides digital input/ output channels, D/A converters output channels as well as input channels for incremental encoder signals. The controller program (for WINDOWS 7-10) allows for a menu-driven operation of the laboratory experiment. The control algorithm of the "Practical Program" consists of state feedback with estimation of the beam angular acceleration, estimation of the ball speed and a disturbance observer to suppress the effects of the friction. The parameters of the controller and of the observers are comfortable adjustable. The controller performance is examined by recording the systems response to changes of the reference and disturbance signals. The signal shapes of the input signals are adjustable as periodic time functions. Measurements of the input and output signals can be represented in a graphic on the PC screen. The graphic output of recorded data may be sent to a window. Its content may be printed, saved as a WMF file or copied into the clipboard. The program allows for storing the adjusted or determined parameters of the plant and of the controller in a binary file. Those data may be loaded again later on.

The Option 50-03 extends the program described with Option 50-02 by a fuzzy controller. This program is useful for learning the concept of a fuzzy control. The comparison of the fuzzy controller with the state feedback controller is easily obtainable by switching the controller mode.

By means of the PC plug-in card MF634 of Humusoft the laboratory experiment "BB50 Ball and Beam" can easily be integrated in Matlab/ Simulink with real-time environment. The user now has the opportunity to test its own controller designs under Matlab/ Simulink.

The Option 50-05 consists of the C++ source files of the PC controller program described with Option 50-02 including library functions for graphic output, controlling the sampling period as well as controlling the PC adapter card. With this option the software may be extended for further studies on i.e. model based fault detection, different observer concepts etc. The Embarcadero C++ Builder V10 is required to generate an executable program.

The Option 50-06 contains a colour monitor suitable for display of the camera image and for service. The monitor will be delivered with a power supply and a connection cable to the actuator.

Technical data are subject to change (Date 4-December-2017)