Schools Integration Project No. 005g

Control Technology Empowering Minds

LEGO + LOGO

Stokane National School, Co. Sligo
Young Scientist Exhibition, RDS Dublin 12-01-2001

"D-Day" in St. Patrick's College of Education, 16th June 2001

A GREAT TIME AT THE RDS

It is not often primary school children are asked to exhibit at a national exhibition, and for the twelve children who travelled to the RDS in Dublin on 12th January 2001, the experience will not be forgotten for a long, long time. The train journey from Ballina began at 06.50 and it was 22.10 before they arrived back on the same platform. The atmosphere in the RDS was new, exciting, and simply cool. Deirdre Butler, the project co-ordinator, was there too to help everybody. When we reached the RDS we rang her on the mobile to announce our arrival, only to hear a mobile a metre away go off .... she was right beside us! We also met Breeda Meleady, project officer with NCTE. We shared stands with some children from St. Brigid's N.S., Castleknock. We gave several demos throughout the afternoon, and to all age groups. We also had a great time looking at the other exhibits, and talking to the other project participants. Thanks to all the parents who travelled, and to Mr. Ed Gunning for giving us the loan of his laptop for our demos. Thanks to Dr. Fred G. Martin of MIT for showing us how to program in LOGO, and to LEGO DACTA also. A special thanks to Deirdre Butler and NCTE for sponsoring our visit, and to ESAT for sponsoring the Young Scientists' Exhibition, 2001.

ANOTHER GREAT TIME AT ST. PAT'S, DRUMCONDRA

The project work continued with enthusiasm, and we chose the legend of St. Patrick and Crom Dubh for the exhibition on 16th June in St. Patrick's College of Education, Drumcondra. This involved visiting some of the sites in the Ballina/Killala area, and then making, programming, and rebuilding several models, as well as some artwork, based on the story. We made lots of models and we took models of St. Patrick, Crom Dubh, Téideach's boat, Dún Briste, the Well of the Branch, the hounds Coinn Iotair and Saidhthe Suaraighe, the linnaun shee and her wheelless sliding cart as well as more bits and bobs. Leona and Denise addressed the group and told everybody what our project was about. They then thanked Deirdre Butler and the NCTE, Fred Martin as well as the parents and teachers who helped make the project a success. Dr. Pauric Travers, President of the College, then presented them with a beautiful plaque for the school, and each pupil received a certificate. Kirsty, Marie and Bryan stood at our stand with Denise and Leona and gave demonstrations. The walls and windows of the hall were covered in maps and artwork, as well as the story which came from the book, "The Stone of Truth and other Irish folk tales" by Douglas Hyde, ISBN 0 7165 2344 2. We all got a quick look at the great projects from the children in the other 12 schools, and it was a fantastic day. We look forward to doing the project again next year. Denise and Leona will have gone to Secondary School, but we will have a new second class.

INTRODUCTION TO LEGO LOGO

You will need Microworlds LOGO for these demos -- go to:

http://www.lcsi.ca

http://www.microworlds.com/solutions/demo.html

to download a demo version for Windows or Mac.

THE TOWER

THE RCX AND TOWER

The RCX is a programmable LEGO brick. A free-roving robot can be built around the brick and this robot can be controlled by the brick. We can program the brick using the LEGO Mindstorms programming language, or using LOGO commands which can be sent to the brick from a tower which is connected to our PC. We used LOGO at the RDS.

THE RCX

LAPTOP WITH TOWER
ATTACHED "BEAMING" LOGO COMMANDS TO AN RCX

THE DOWNLOAD PROCESS

The program for the RCX is written on a PC.
LOGO commands are sent from the Yellow Brick Logo application on a PC via cable, to the tower -- the wedge-shaped black box in the image on the left. The tower is a transceiver. It "talks" to an RCX within range, and if one is found, the program will start to "beam down" or download.
Since the PC-to-RCX connection is wireless, the robot can't hurt the PC.

THE RCX WITH MOTOR AND SENSORS ATTACHED

THE RCX WITH MOTOR
AND SENSORS ATTACHED

An RCX has 3-outputs and 3-inputs.
The RCX shown on the left has a motor attached to output A. A touch sensor is attached to input 1 and a light sensor is attached to input 3. A transceiver (infrared communications port) is located at the end of the brick. A transceiver is a transmitter and receiver in one unit. A small LCD panel, surrounded by RCX control buttons coloured red, green, grey and black, shows what's happening when a program is running.

SENSOR TESTS
Note: For these tests you will need an RCX with motor and sensors attached.

A TOUCH SENSOR

THE TOUCH SENSOR TEST

Note the yellow button on the touch sensor. This is a push-button switch like that on a door-bell. Note that four of the six studs on top have electrical contacts.

Attach the touch sensor to an RCX and turn on the RCX by pressing the red On-Off button. Press the black View button. You will see 1023 on the LCD and a black triangle pointing to input 1. Now press the yellow tip of the touch sensor connected to input 1 and see what's on the LCD. The number will now be very low.

What has happened?

The RCX has read the "pressed" and "released" states and shown these as a low number and a high number. Because it shows just 2 numbers we call it a digital device. A robot could use this sensor to turn if it touches a wall.

A LIGHT SENSOR

THE LIGHT SENSOR TEST

Note that the light sensor has a light transmitter and a light receiver to measure the light reflected back. A cable comes from the light sensor body to an electrical plate.

Attach a light sensor to input 2 of the RCX and turn on the RCX by pressing the red On-Off button. Press the black View button. You will see 1023 on the LCD and a black triangle pointing to input 1. Press the View button a second time, and the black triangle will point to input 2. Now read the number on the LCD. Place the sensor over a dark object and read the number again. Try several different objects, and note the number changing.

What has happened?

The light sensor on the RCX has received different levels of light and the RCX has shown these as different numbers. Because the light sensor shows several different levels to the RCX we call it an analogue device.

THE ROTATE SENSOR

MORE SENSORS

The rotate sensor can be useful for telling the RCX, for example, how much a robotic arm has turned.

The temperature sensor can tell, for example, if a motor is over-heating and the RCX can shut down everything.

Both are analogue devices.

THE TEMPERATURE SENSOR

USING LOGO WITH THE RCX
Note: For this section you will need an RCX with motors and sensors attached, and a second RCX. You will also need a PC, a tower and the Yellow Brick Logo application.

THE YELLOW BRICK LOGO SCREEN

To program the RCX, we open the Yellow Brick Logo application, and the Yellow Brick Logo screen above appears. We type our LOGO commands in the three white areas. We look at each of the white areas in the next sections.

YBL COMMAND CENTER

YELLOW BRICK LOGO COMMAND CENTER

Commands typed in the Yellow Brick Logo Command Center, followed by ENTER, go straight to the tower to be sent to the RCX.

Place the RCX near the tower, with both tranceivers facing each other and attach motors as for previous tests. Turn on the RCX by pressing the red On-Off button, and try the commands shown below.

Type beep in the Brick Command Center and press ENTER to make the RCX make a beep sound.
Type beep wait 10 beep wait 10 beep
and press ENTER to hear the result.
Try repeat 3[beep wait 10]
and press ENTER.

Type a, on, followed by ENTER, and the motor attached to output A will turn on. Type a, off, followed by ENTER to turn it off. Typing ac, on,followed by ENTER, will turn on motors attached to output A and output C.
Press the On-Off button on the RCX to quit.

THE PROCEDURES WINDOW

A LOGO procedure is a list of instructions written on lines following a line beginning with to and before a line with the word end on its own.
The following procedure, when downloaded, could be used to turn on motors attached to outputs A and C, and switch both off after 2 seconds.

to turnon-a-c
ac, onfor 20
end

Note: to and end must be present in a procedure. We are teaching LOGO to do a task. Call it programming in LOGO, if you like. We can't teach it to off because it knows how to off already, but there are many other words it doesn't know, so we can have plenty of fun teaching it.

to dance
a, onfor 10 b, onfor 10 rd
dance
end

This procedure calls itself, so dance goes on and on and ....

THE RUN BUTTON LINE

After a procedure is written, it can be downloaded to the RCX by placing its name in the Run Button Line and clicking the Download button.
If we type turnon-a-c in the Run Button Line after we have taught LOGO to turnon-a-c, the procedure turnon-a-c will be downloaded to the RCX when we press the Download button. The program will not run on the RCX until we press the green Run button on the RCX. Press Run again to stop the program. We could turn off the RCX and next day, when turned on, it would still remember how to turnon-a-c, unless we downloaded a new procedure.

SAVING OUR PROGRAMS

We can save procedures by going to File, Save Project As, and giving the procedure in the Procedures Window a name. To use these again we go to File, Open Project, and choose from the library of saved procedures.

LOGO PROCEDURES AND SENSOR TESTS

THE YBL TOUCH SENSOR TEST

Write the following procedure and download it:

to touch-it
a, on when [switch1] [rd]
end

Press Run on the RCX, and the motor attached to output A turns on, and reverses direction each time the yellow button of the touch sensor attached to input 1 is pressed. Press Run again to stop the program running.
Now try [a, off c, onfor 10] instead of [rd] to see what happens.

THE YBL LIGHT SENSOR TEST

Write the following procedure, taking care with the spaces, and download it:

to see-it
if sensor2 > 750 [beep]
see-it
end

Press Run on the RCX, hold the light sensor in your hand with its light beaming down on the RCX and see if the RCX detects whether it's over a yellow set of studs on the RCX or not. It should beep just like the scanner at the supermarket checkout, but if not, try changing the number 750 to a different number. This procedure is recursive, because in the third line, see-it calls itself. It will just keep testing sensor attached to input 2.

RCX2 CALLING RCX1 ...... COME IN PLEASE......
Note: For this test you will need a second RCX.

Get a second RCX, type the following program and download it to the RCX, which we will call RCX2:

to tell-rcx
every 10 [send 1 + (random % 3)]
end

Now switch off RCX2, and write and download the program on the right to the RCX we used previously with motors attached. We will call it RCX1.

to listen-and-obey
loop [waituntil [newir?]
if ir = 1 [beep]
if ir = 2 [a, onfor 5]
if ir = 3 [c, onfor 5]]
end

Turn on RCX1 and RCX2 and press Run on both. RCX2 creates random numbers between 1 and 3 each second and sends these to RCX1. If RCX1 hears 1, it beeps. If it hears 2 it turns on motor attached to output A for 5-tenths of a second. What if it hears 3? Yes, it turns motor C!