Hades logo    Hades applet banner

TAMS / Java / Hades / applets (print version): contents | previous | next

Animated 2 Floor Elevator

Animated 2 Floor Elevator  screenshot


This applet demonstrates the 2 floor elevator controller, used as an example for state-machine design in many textbooks. To motivate and illustrate the elevator controller design, the applet contains a special simulation component that visualizes the elevator and its internal/external control button.

Use the popup-menu ('edit') on the elevator component to open the window with the elevator visualization. Press any external and/or internal buttons on first and ground floor and watch the behavior of the elevator controller. You can also open the state-machine editor to watch and edit the controller. The following image shows a screenshot of the applet with both the elevator animation and the state-machine editor open at the same time:

Elevator has four buttons. Two external buttons and two internal buttons (in the elevator car). In addition, there are two floor level sensors. When the elevator is on the ground floor, the ground sensor is ON. If the elevator moves up, the ground sensor is OFF, and the first level sensor will be switched ON when the elevator arrives on the first floor. The engine and direction are elevator inputs.


engine: ON and OFF

direction: move up (ON), move down (OFF)


FirstSensor: ON if the elevator is on first floor, otherwise OFF

GroundSensor: ON if the elevator is on ground, otherwise OFF

out_up and out_down: External buttons. Switch ON if pressed, and stay on until the elevator arrives in correct floor.

up and out: Internal buttons. Switch ON if pressed, and stay on until the elevator arrives in correct floor.

Component written by Ulisses Chippe, Giliardo Freitas and Ricardo Ferreira, DPI, Universidade Federal Vicosa, Brazil, cacau@dpi.ufv.br

To edit the state-machine, activate the popup-menu on the FSM symbol and select the edit menu item. This opens the editor window for the FSM, which uses a mode-oriented user-interface.

Run the applet | Run the editor (via Webstart)

Impressum | 24.11.06