This paper presents the Automatic Control Telelab (ACT), a remote laboratory for education in robotics and automation developed in Siena. A special attention will be devoted to the new ACT process, a Lego mobile robot, which has been recently added to the telelab. Remote users can control the Lego mobile robot, and all the other processes, using an Internet browser. Moreover users can design new controllers by means of the Matlab/Simulink environment. The ACT home page is http://www.dii.unisi.it/∼control/act.
THE AUTOMATIC CONTROL TELELAB
The Automatic Control Telelab is a remote laboratory mainly intended for educational purpose, and since 1999 it has been used in control systems classes.
The aim of the project is to allow students to easily put in practice their theoretical knowledge of robotics and automation without restrictions due to laboratory opening time and processes availability. The ACT is accessible 24 hours a day from any computer connected to the Internet by means of any common browser. No special software or plug-in is required. Users can design new controllers by means of the Matlab/Simulink environment.
The aim of this project is to allow students to perform remote control experiments on a mobile robot through the Internet. In particular, the robot is made of Lego Mindstorms bricks, and is a part of the ACT.
The control of a mobile robot needs special features, such as security systems to prevent the robot to go out the working area, an automatic recharge system, a mechanism to detect the robot position, and so on. All these aspects are described in detail in Section IV.
In this section the mobile robot and other hardware components involved in this project are described.
A. The Mobile Robot:
The mobile robot has been built with Lego Mind-storms bricks. Lego Mindstorms allows the use of the so-called RCX, a special brick which contains a microprocessor and which allows to be connected to three sensors (e.g.encoders, light or touch sensors) and three actuators (usually DC motors). Moreover, it is able to store and run up to four programs. The RCX communicates with a PC through a serial or a USB infrared tower, by means of which it is possible to download a program and to perform other basic operations.
In this section a mathematical model of the mobile robot is described. Some robot parameters, obtained both on Lego Mindstorms data sheets and on an identification analysis, are reported . Since the RCX uses integer values steps to drive the motor, they have been referred to as units (they do not haveany physical meaning).
A SESSION EXAMPLE
From the home page of the ACT it is possible to access to general information pages, as for instance the user guide of the laboratory and the list of available processes. For every process it is possible to show a system description as well as a sample movie. In the following we refer to the Lego mobile robot.
In this paper the remote control for a Lego Mindstorms mobile robot has been presented. The remote experiment has been developed inside the Automatic Control Telelab environment, a laboratory which allows the remote control of physical processes.
By means of this facility, students can perform robotics and automation experiments through the Internet in a safe and easy way. Users can design their controllers through a Simulink model and test it on the actual robot. Students who experienced this facility provided in general very positive and enthusiastic comments.
Future developments regard the student competition also for the Lego robot, and the possibility to create virtual obstacles which must be avoided by the robot. This last feature will allow students to design and test path planning algorithms.
Authors: Fabio Carusi | Marco Casini | Domenico Prattichizzo | Antonio Vicino