Schools Integration Project No. 005g

Control Technology Empowering Minds

Stokane National School
Scoil Náisiúnta an Stuacáin

Thoughts on Robots

Cúpla focal mar gheall ar nithe róbócha

What are Robots?

A robot can be described as a machine which thinks and makes decisions, and modern homes have several of these devices in simple and complex form. When an electric kettle is filled with water, plugged in and switched on, it doesn't need to be switched off manually  – it does this after the water it contains boils, and it stays off. A temperature sensor, called a thermostat, works with the heating element to achieve this. We say the kettle is programmed to switch itself off after its contents reach the desired temperature.

An electric kettle

The program controller shown on the right comes from an old automatic washing machine, and consists of twelve wafers  with toothed edges (shown in light blue) on the same shaft. A small motor, (shown on the bottom right-hand side) connected to a gear-train, slowly rotates the shaft, and the wafers cause the switch contacts to make or break when a tooth or a gap hits a contact. A rack of 6-contacts is shown face up on top, with the controller open. Another rack is shown in place underneath. One wafer controls the heating element, another pair control the water inlet valves, another pair the clockwise/anti-clockwise motor directions .... the pump to discharge the waste water...... The program selector dial is attached to the end of the shaft shown on the left-hand side. An automatic washing machine has several sensors. When switched on, it checks if the door is closed, and won't start its cycle if it isn't. It proceeds to fill the drum with water until another sensor switches this process off ....... Do we need all this for schools? Certainly not, but it's no harm to be looking at it, and the LEGO Mindstorms project is an ideal medium for beginning to understand the principles fundamental to process control and power transmission systems in a fun and enriching way. It places the child right at the centre of the system since theory-to-product is instantaneous.

Program controller from an automatic washing machine

What we learn about

LEGO bricks attract most children since there are so many ways of attaching them to each other to create toys, buildings and  abstract creations. Motors can be attached to the bricks and gear-trains put in place so that  the models can then be made to move in a predetermined  way. The basic principles of pneumatics can also be touched on. The use of sensors which connect to a special programmable brick (which doubles as a battery-box) called an RCX adds a most rewarding dimension to the work and there is scope for the individual as well as the team player. Right throughout the workshop sessions language development is evident, and the emphasis is always on the visual and practical. The children in the school have been interested in robotics for many years, and we have been using LOGO and BASIC since 1989, with a robot, and some of the former children were used to the concept of switching of motors using relays and using light and temperature sensors in control. We sampled the classroom temperature over one 24-hour period per term, (using a BBC Master and a thermister) at fifteen minute intervals, and printed out the results. The light sensor was used to detect “burglars” breaking its light source, and its readings were shown on a graph written in BASIC. We purchased “Mission Control” (Sherston Software) in 1999. This simulates process control in a factory, and is similar to what happens in a milk-packaging unit, or in any factory where CAM is used – a great introduction to robotics. The children visited Pure Fresh Dairies, Duffy's Bakery and Carrabine Joinery in Ballina, on 30th September 2000, to see examples of process control in action. By then they had become familiar with the RCX and some of its main capabilities, and the class tour really motivated them to continue as it convinced their parents that this SIP was for real – without the parents on side a teacher’s task is always much more difficult. At the dairy, it was obvious that the cartons had to be filled and packaged in tens, so five were swept off the conveyor belt at a time and pushed onto another belt. The first belt had to pause while this was done, and the second belt paused after a short distance until the second five cartons pushed on the first five. These were then shrink-wrapped and sent for storage at 4° C.

At the joinery, the school name was etched on a slab of wood using a router which was controlled by a computer. Two of the children helped select the font, and type in the letters, while two others chose the borders around the text. The machine did the rest, exchanging router bits during the process.

They also toured the window-frame manufacturing section and were amazed that the computer could calculate the glass sizes for the panes to minimize glass wastage, and could then cut each pane to a precise measurement. 

Daniel Carrabine and the children eagerly watch the computer-controlled router, (Sept. 2000) as it etches out "Stokane N. S." on the slab of mdf.

A huge sheet of glass lies on the deck waiting to be cut into panes by this computer-controlled glass-cutter in Carrabine Joinery, Ballina

The dough is rolled into a thin narrow sheet, it passes over trays and a measured amount of the apple/syrup mixture is poured in as the conveyor belt moves along in Duffy's Bakery, Ballina.

The tart lids are on, the edges crimped and a hole is punched in the centre of each tart as it passes by. The tart on the right is being seperated from the sheet of dough and it will be taken out and placed on a large baking-tray (see below)

Kelly is caught on camera as Catherine explains the baking process. "The baking-trays pass slowly through a tunnel; when they emerge, their contents are baked", she explains.

Removing the tarts from the conveyor belt is done by hand. All workers (and visitors) to Duffy's Bakery must wear protective clothing and gloves.

Thanks to Daniel Carrabine of Carrabine Joinery, Ballina, for showing us around. Even though he was on crutches, he could cover huge steps because of his great height! Tony and John Duffy treated us very well at Duffy's Bakery, Ballina, and we each had a tart for tea when we got home! Thanks to all the staff as well, especially Catherine.

An angel figure on CAD
Daniel loads this image from an image bank and chooses the tools for each detail.

Busellato 6000XL in action

The router takes the program from the PC and carves out the design on a slab of wood.

The angel figure on wood

The finished product!

As a group of young LEGO engineers, we would recommend the project to any school with a little space and even a slight interest in construction – there is a great learning and fulfilling experience waiting, and you'll have plenty to show and talk about if you have a digital camera and a printer! For our project, we chose the legend of St. Patrick and Crom Dubh. The story goes that St. Patrick tried to convert the local tyrant chieftain, Crom Dubh, who lived in a dún on a peninsula in North Mayo. Crom Dubh, who responded by attempting to murder the saint, was isolated in his dún after Patrick caused the collapse of the arch connecting the peninsula to the mainland. The then powerless tyrant finished his days marooned on the stag now known as Downpatrick or Dún Phadraig. Dr. Séamus Caulfield (Prof of History, UCD) visited the stag by helicopter in 1980 and stayed overnight there, and Bill Whelan composed a haunting piece called Dún Briste. The last Sunday in July  – Garland Sunday  – is called Domhnach Chrom Dubh. The children made models of a boat, the fire, Crom Dubh's dún, the bridge to the stag which was operated using pneumatics and the two hounds. Several small booklets were also produced using Storybook Weaver, and Microworlds LOGO. An adventure game based on the story of St. Patrick and Crom Dubh is nearing completion. A tour was organised to the places mentioned in the story, and project work on the life of St. Patrick can now be easily undertaken. 

Our Project Work

Fred Flintstone's scooter, Thriller

The image shown on the left is a simple two-wheeled vehicle which uses a single 12-stud LEGO beam for a chassis. If placed on a slope, it rolls downwards, gaining speed as it does so. Is it programmed? In a way it is, because if we place it on the same slope several times, its actions will be exactly the same each time. Its movements will be predictable. 

As a model is in the making, we talk about what we want it to do and we use the names of its constituent parts. We take pride in knowing the correct terms to use.

"Tús maith leath na hoibre" Parts list: 2-hubs, 2-tyres to match hubs, 2-grey axle-stubs and one 12-stud beam.

Scooter Fun 

Make two scooters and race both to see if they are matched for pace. Try them on different surfaces, e.g. on a towel or on cardboard, or an a sandy slope. Which surface is best? 

Hide the scooter and tell somebody what they need to make it, and how to make it, but don't show them your model. When completed, compare both. Are they both the same or do they make a symmetrical pair? Ask somebody who is left-handed to make a scooter and see if yours and his are a symmetrical pair. 

Place a pea or a small piece of chalk on one of the studs and allow the Thriller roll forward until it hits a solid object such as a book placed at the other end of the desk. Why did the pea not stop when the scooter stopped? Why do people need to wear seat-belts in cars? 

Try changing one of the wheels for a bigger size. Does the scooter move faster? Do both wheels turn at the same speed? Why? 

Raise one end of a desk by placing books underneath, and place a measuring tape lengthwise on the desk. Place the Scooter on the desk at the higher end so that it is free to roll forward towards the other end. Place a chalk mark on the desk at the rear wheel and count Zero …. One …. Two …. Three …. as the vehicle rolls forward, and continue to place chalk marks at the now moving rear wheel at each count. Note that the chalk marks are getting further apart as the scooter rolls forward

Kirsty and Anne-Marie

John and Darragh

Kelly and Tara

Bryan and Paul

What are they at? 

If somebody came into the classroom at LEGO Mindstorms Workshop time and saw the scenes above they would wonder what these young engineers were at. A closer look would reveal the hive of activity, from selecting a piece which might fit to deciding that the design needs fundamental change. Kirsty and Anne-Marie are busy checking the gear-train before fitting the RCX on top. The RCX is a special battery-box which can be programmed to control a robot built around it. These two girls like to place the motors low down on the chassis. John, who works alone, likes to use big wheels and most of his models are tall, slow-moving and powerful. Darragh builds straightforward models. Kelly is working from a kit, while Tara is adding a belt drive to her model. A belt drive is much easier than a gear-train to put together. On the right, Bryan and Paul are exchanging views on how best to hide the RCX, without its IR lens getting covered. When these projects were in progress during first term 2000, the differential gear-box wasn't even mentioned!

We include here some of the photographs from our project, St. Patrick and Crom Dubh. Thanks to Kirsty, Anne-Marie, Grace and Marie for taking the photographs.

Anne-Marie with the touch-sensor car

Bryan with "St. Patrick" and Darragh with his soap-box car

John with his robot

Kelly and Fiona with their robotic gadget

Kirsty with Téideach's boat

Marie and Grace hold Crom Dubh's fire

Paul is making a cat for Crom Dubh

New lad, Richard, has just completed his robot

Shane displays St. Patrick about to break the bridge

The tax-collector, or the trickster, shown by Shane

Tara displaying a cross dog, Saidhthe Suaraighe

Edward and Vincent holding another vicious dog, Coinn Iotar