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FACULTY OF ELECTRICAL
ENGINEERING AND COMPUTING DEPARTMENT OF ELECTRONIC
SYSTEMS AND INFORMATION PROCESSING |
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LABORATORY
FOR SYSTEMS AND SIGNALS |
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A
student project within the course
“SOFTWARE DESIGN FOR MEASUREMENT AND PROCESS SYSTEMS”
Telecontrol
of a Mindstorms® NXT Robot
Technical documentation
Kristina Bashota
Tibor Čordaš
Dalibor Jelača
Iva Jelenčić
Vedran Koruga
Damir Kušević
mentor
Zagreb,
February 6, 2008.
Contents
Introduction
.............................................................................................................................3
Description of the comunication
and robot functioning
...........................................................4
Enabling the web interface ........................................................................................................5
Appendix .................................................................................................................................6
Introduction
For the purpose of this project a Mindstorms® NXT robot is used.
Accessories that were used for
the robot are: an ultrasonic sensor, touch sensor, sound sensor and opening/closing the robot’s claws.
Managing the robot is programmed
in the C++ language. A free Bloodshed Dev-C++ compiler was used for
that purpose and was downloaded from the following website http://www.bloodshed.net/devcpp.html.
The programming was simplified by downloading already written libraries from the
website http://www.norgesgade14.dk/bluetoothlibrary.php.
It is quite easy to communicate with the robot via a Bluetooth
connection. After establishing a connection it’s necessary to find out which
COM port is used by the robot.
Instructions are sent to the robot directly through the C++ files. There
are six classes which enable:
- Establishing and disconnecting a Bluetooth
connection,
- Control over the motors,
- Reading the data from the sensors,
- Naming the Brick
and reading the firmware,
- Sound reproduction
- Using the ultrasnonic sensors.
The web interface is designed to
enable maneuvering the robot. The user can choose actions for the robot (moving forward / backward, turning left / right,
opening / closing claws).
Data received from the sensors are clearly displayed on the interface so the
user can decide on his next move. Managing the robot from a remote computer
through the web interface is enabled by the server computer.
Description
of the comunication and robot functioning
Bluetooth
connection
The COM port for Bluetooth
comunication is opened with the function
int connect(char *port), is closed with the function disconnect().
Managing
the motors
The robot has three motors which
are managed by the following functions. Motor(int output_port, Serial *cp) transfers
the port number and the pointer to the serial connection. The function int
on(int speed) starts up a motor with the set velocity. If the negative
algebraic sign is added, the motor will rotate in the counter direction. The int
stop() function stops the motor, whilst the int reset_rotation()
resets the motor rotation.
The movement velocity of the robot forward and backward is set at a fixed
value of 35 (the velocity can be chosen arbitrarily and the velocity range is
from 0 to 100). The velocity of turning left and right is reduced to a quarter
of the fixated value for easier steering. The
robot's movement instructions given from the web interface are written in a
textual file named upravljanje.txt which is created
by the program itself.
Managing
the sensors
Data received from the ultrasonic sensor and the touch sensor has to be
forwarded to the computer which will be displayed on the web interface.
The data given from the ultrasonic sensor is read in an infinite while loop. By calling the sonar.distance()
function the sensor is asked to measure the distance from an obstacle. That
information is sent to the computer via a Bluetooth connection for futher
processing. (The given function can return the distance either in cm or
inches.) The information is then written in the textual file udaljenost.txt which is created by the
program and is a link to the web interface.
The condition of the touch sensor is also cheked in the above mentioned
infinite loop. The touch sensor is used for detecting low obstacles lying on
the ground such as cables, books, pencils etc. By calling the touch.read()
function the sensor is asked to detect obstacles. If the sensor comes across an
obstacle, the robot sends a message via a Bluetooth connection to the computer
that the sensor has been pressed. When the sensor is released, a message is
also sent to the computer. The condition of the sensor is also written in the
textual file tipkalo.txt which is a link
to the web interface.
Managing other accessories
The instruction speaker.beep() enables playing a
sound from the sound sensor.
Opening and closing the robot’s claws is enabled by using the motorA.reset_rotation()
and motorA.on(10,45)
(10 is the opening and closing velocity, 45 is the angle) functions.
Enabling the web interface
After designing a web interface in a html editor, it's
important to follow the following steps for making the comunication with the
robot possible:
·
Download and install apache
web server (version 2.2.8,
although the version isn't that important) from the following website
http://ftp.carnet.hr/misc/apache/httpd/binaries/win32/apache_2.2.8-win32-x86-no_ssl.msi
The installation is simple, just choose next.
·
Download and install the php
from the website
http://www.php.net/get/php-5.2.5-win32-installer.msi/from/a/mirror
The installation is simple, just choose next. At one moment
it will ask for which program to install the module. Mark the apache 2.2.x. Also, it will ask for the
path of the configuration file of the apache.
It's located in the conf directory
which is in the directory where the apache
was installed.
·
Copy the directory with the web page within the htdocs directory which is located in the
apache directory. Copy the main
program for managing the robot to the mstore/tmp
directory and start the main program.
In this example the html
page is named index.html and is saved
in the mstore directory with all the
files (textual files and the jpeg pictures of icons used for the interface)
needed for the interface to work properly. In order to access the website link
to
localhost/mstore
from the local computer or to IP-address/mstore
from a remote computer.
Appendix
The commented code appended to
the documentation is as follows.
#include <cstdlib>
#include <iostream>
#include <string>
#include <conio.h>
#include <stdlib.h>
#include "serial.hpp"
#include "brick.hpp"
#include "sound.hpp"
#include "motor.hpp"
#include "sonar.hpp"
#include "sensor.hpp"
Serial bluetooth;
Sonar sonar =
Sonar(0,&bluetooth); //ultrasonic
sensor on port 1
Sensor touch =
Sensor(1,&bluetooth); //touch sensor on port 2
Brick nxt = (&bluetooth);
Sound speaker = (&bluetooth);
Motor motorA =
Motor(0,&bluetooth);
Motor motorB =
Motor(1,&bluetooth);
Motor motorC =
Motor(2,&bluetooth);//Motor C on port 3
Sound zvuk;
using namespace std;
int main(int argc, char *argv[]){
FILE *fp, *fp1, *fp2;
int brz; //velocity
int naredba; //managing the robot
int j,k,l; //flags for the files
int i,x,y; //flags for the instructions
int distance;
int tipkalo; //variable for touch sensor
char string [4];
if(bluetooth.connect("COM6")){//connects
to the NXT through COM port 6
cout << "Veza OK!"
<< endl;
nxt.set_name("LEGO"); //Set
the brickname to LEGO
cout << "Firmware verzija:
" << nxt.firmware_version() << endl;
touch.type_and_mode(TOUCH,BOOL_MODE); //initialize
the touch sensor
sonar.setup(); //initialize the
ultrasonic sensor
//intialize the flags and variables
brz=35; // velocity
naredba=13;
i=12;
j=0;
k=0;
l=0;
x=1;
y=1;
distance=0;
tipkalo=0;
// cout << "Postavite zeljenu
brzinu!" << endl;
// cin >> brz;
while (naredba != 1){
Sleep(10);
//load instruction through file
"upravljanje.txt"
if ((fp =
fopen("upravljanje.txt", "r+")) !=NULL){ //create file
j=1;
}
if(j){
naredba=fgetc(fp);
fclose(fp); //close file
fopen("upravljanje.txt",
"w");
fclose(fp); //close file
j=0;
}
//write distance to file
"udaljenost.txt"
if ((fp1 =
fopen("udaljenost.txt", "w"))!=NULL){//create file
k=1;
}
if(k){
itoa(distance,string,10);
fputs(distance,string,fp1); //write
information about the distance to the file
fclose(fp1); //close file
k=0;
}
//writing the condition of the
touch sensor to the file "tipkalo.txt"
if ((fp1 =
fopen("tipkalo.txt", "w")) !=NULL){ //kreiranje datoteke
l=1;
}
if(l){
tipkalo=touch.read();
fputc(tipkalo,fp1); //write
condition of the touch sensor to file
fclose(fp1); //close file
l=0;
}
// controlling movement and sensors
distance=sonar.distance(); //measuring
the distance
// if (distance < 35){
// motorB.stop();
// motorC.stop();
// }
naredba=naredba-48;
if (naredba == 8 &&
naredba!=i){ //both motors forward
motorC.on(brz);
motorB.on(brz);
i=naredba;
}
if (naredba == 5){ // both
motors stopped
motorC.stop();
motorB.stop();
i=naredba;
}
if (naredba == 2){ // both motors
backward
motorC.on(-brz);
motorB.on(-brz);
i=naredba;
}
if (naredba == 4){ //move left
motorC.on(-brz/4);
motorB.on(brz/4);
i=naredba;
}
if (naredba == 6){ //move right
motorC.on(brz/4);
motorB.on(-brz/4);
i=naredba;
}
if (naredba == 0){ //sound
speaker.beep(200);
i=naredba;
}
if (naredba == 7){ //open claws
motorA.reset_rotation();
motorA.on(10,45);
x=0;
y=1;
}
if (naredba == 9){ //close claws
motorA.reset_rotation();
motorA.on(-10,45);
y=0;
x=1;
}
if
(naredba == 17){ //moving right
motorC.on(brz/2,30);
motorB.on(-brz/2,30);
}
if (naredba == 18 ){ //moving
left
motorC.on(-brz/2,30);
motorB.on(brz/2,30);
}
if (naredba == 19 ){ //moving
forward
motorC.on(brz/2,135);
motorB.on(brz/2,135);
}
}
bluetooth.disconnect();//disconnect
Bluetooth
}
else{
cout << "Bluetooth veza nije
uspostavljena!" << endl;
}
Sleep(200);
exit(1);
}