Random NXT: BlueToothKiwi's NXT blog

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noreply@blogger.com (BlueToothKiwi) — Mon, 04 Nov 2013 19:24:00 +0000

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A NXT Amphibious Vehicle

noreply@blogger.com (BlueToothKiwi) — Sat, 05 Jul 2008 19:18:00 +0000

Yesterday, it rained all day and we had two inches (5 cm) of flood around our house. So we designed this robot initially to go and fetch the mail so we don’t have to go in the rain and get our feet / shoes wet.

I have not had a chance to test this outdoor properly yet - as it is still raining. But we did have 20 minutes break in the rain - long enough to take this picture.

This is our first version of a NXT Amphibious vehicle. We tried to make it so that it can crawl over rocks like the Packbot [iRobot] / LNE [Brian Davis] / SCAT [222Doc] and also can track through 3" of water by raising its head and NXT using the two side arms while moving. We also want to add some buoyancy in the middle so that it can float and use the arms to 'swim' through the water and when it reaches the water edge, start climbing walking with the flippers and when it reaches flat ground use the flippers and tracks to move really fast.

We also have plans to make it so that the long tail will be pivoted at multiple places so that the tracks move like a snake and will aid with the motion. But it is a bit hard to do that - as the tracks allow very little lateral bending and not designed to be flexible from side to side!

I will post the detailed instructions in NXTLog shortly. It has some really clever stuff to do with using the Differentials in a new way - driving three tracks with two motors.

The clone wars: New Star Wars film coming next month

noreply@blogger.com (BlueToothKiwi) — Tue, 01 Jul 2008 12:46:00 +0000

I have always been a fan of Star Wars films - and recently I saw a trailer for the new animated Star Wars Film: The clone wars. The new film is weeks away from being released in Europe and USA - and from what I have seen of the CGA animation - it sure looks cool.

So last week, I decided to build one of my favourite Star Wars droid: The Hailfire. The IG-227 Hailfire, was a droid tank constructed for the InterGalactic Banking Clan prior to and during the Clone Wars.

If you got a NXT retail kit, two universal joins and the two green wheels from the Green devastator, you can build your own wheel droid. You can find the instructions on LEGO NXTLog. The model also has an optional dual missile launchers (controlled by NXT) and an RFID sensor to identify other droids.

And talking of NXTLog, LEGO have just introduced a new account system. So while you are there check out the new stuff.

Making your own Wall-e with NXT

noreply@blogger.com (BlueToothKiwi) — Wed, 25 Jun 2008 17:56:00 +0000

This weekend many people would be able to see the Disney Pixar film Wall-e in Europe and USA. The film about a robot that falls in love is one of the most creative to come out of the Disney-Pixar studio for a while.

To mark the release of the film, the oficial web site has a 'Build your own robot' section where you get to choose the looks / behavour / mobility etc.

And of course, if you got a NXT - you dont need to go to a web site to design a virtual robot. You can of course build your own real Wall-e! Well almost!!

To get you started, here is some inspiration. This version, designed about a year ago was based on a leaked picture of the robot and it won one of the NXTLog building challenges last year. We had a lot of fun creating it - it can be built with the components from one NXT retail kit and one 2007 TECHNIC Bulldozer kit.

If you want instructions on how to build it, check out the NXTLog instructions here.

World's Fastest NXTien

noreply@blogger.com (BlueToothKiwi) — Sat, 07 Jun 2008 20:58:00 +0000

We built this really fast NXT based vehicle over the weekend to see how far you can step up the rotations from a NXT motor before you reach the point where the power delivered to the wheel is no longer enough to make the vehicle move.

And here is a video to go with it:

NXTilicious Xmas

noreply@blogger.com (BlueToothKiwi) — Wed, 26 Dec 2007 19:05:00 +0000

I hope you all had a fantastic Christmas yesterday and you found lots of MINDSTORMS and LEGO stuff under the Christmas tree.

We had a fabulous Christmas day yesterday - We started the day with the kids opening their presents... and watching the kids playing with the roller skates they got for Christmas and other cool toys while we stuffed ourselves with food and wine.

The highlight of the day was giving all the kids their own NXT for Christmas: I have had enough of having a single MINDSTORMS NXT in the house shared between four people - and decided it would increase the peace and harmony in the house if every child had their own NXT.

So for Xmas each of our children got one NXT, four NXT sensors each, and a selection of motors - including TECHNIC & PF XL motors, PF standard motors, remotes and power supplies.

To top it all, we decided to have a building competition , where everyone get an hour to dream up and build a machine (with or without the NXT) and fight each other.

To make it interesting, we piled up a room full of TECHNIC pieces they can use in addition to the box full of LEGO MINDSTORMS goodies and TECHNIC pieces they got for Christmas:

The building went really well. We had one hour of peace when the three kids were busy concentrating on buildng their best creations, whilst our 11 month old baby watched them from the rocking horse she got for Christmas.

At the end of the construction, we had the contest - we used the old Sumo ring we built two weeks ago for fighting. It was really etertaining to watch the contest. Our 12 year old boy won the first price after knocking the other two off the ring. Our 7 year girl won the fastest and cutest robot price for the four motor vehicle .. and our 14 year old boy got the most amusing and ingenious robot design price with his NXT based robotic caterpult with multiple motors and a pneumatic projectile launcher..

Why not share what you did for Christmas?

In the mean time, I like to wish you all a happy new year and a prosperous 2008.

LEGO MINDSTORMS NXT Sumo robot Competition

noreply@blogger.com (BlueToothKiwi) — Wed, 05 Dec 2007 05:56:00 +0000

Robot sumo is one of the fastest growing sports around. Now if you own a LEGO MINDSTORMS NXT, you can join in as well:

The LEGO NXTLOG is running a building challenge where NXT owners can design and submit a LEGO Sumo robot that could actually compete in a LEGO Sumo match.

And here is a twist: A panel of MINDSTORMS experts will build a select number of finalists. The finalist robots will compete in an exclusive LEGO Sumo match run by the MINDSTORMS experts. The NXT Sumo robot that wins the most rounds in the match will be declared the winner of the MINDSTORMS NXT Sumo Competition.

You still have plenty of time to enter the MINDSTORMS NXT Sumo robot competition run by the LEGO company. The deadline is mid December.

Are you up for it? Do you want some inspiration to get you started? Here is five minutes montage of pure Sumo heaven:

I will be posting more stuff here in the next few days:

How to make a Sumo ring in 30 minutes

noreply@blogger.com (BlueToothKiwi) — Tue, 04 Dec 2007 01:43:00 +0000

In recent weeks my children and I have been having lots of fun making and fighting Sumo robots with LEGO MINDSTORMS NXT. However, I wanted to make the fights to resemble the official Sumo rings used in competitions similar to how it is suggested in the LEGO NXT Sumo web site.

Making a simple Sumo ring for the family is really easy. The following explains how a Sumo ring can be built in 30 minutes with easy to find stuff.

Things you need:

· Few sheets of A3 paper
· 1 x pair of Scissors
· 1 x can of white paint
· 1 x can of black paint
· 1 x knife / box cutter
· 1 x bottle of mineral turpentine (just in case you have to wipe any drips)
· 1 x piece of wood
· 1 x hard board
· 1 x masking tape
· 1 piece of string about 1 m
· 1 x PVA bonding / Glue

(1) Make a stencil with paper

Step 1 - make a giant square of paper: Join up few sheets of A3 papers together with masking tape to make a giant square just over 4 feet by 4 feet [1.25m x 1.25m]

Step 2 - Draw a giant circle: Rest the giant paper on something solid (like a wooden deck) and hammer a nail into the middle of the paper

Tie a piece of string on the nail with a bit of slack so it can freely rotate around the nail. Tie a pen or a pencil to the other end - you now got a poor man's compass.

Using the stretched string as guide, draw two concentric circles – the outer one 2 feet (61 cm) radius and the inner one 22 inches (56 cm).

Step 3 - Cut the stencil: Use a knife or pair of scissors to cut along the mark. You will have three stencils: a round circle, a ring, and a outer bit.

(2) Painting
Step 4 - Paint the outer bit white

First use the smaller circle template – place the stencil on the hardboard - you may use a glue stick to prevent it moving while spraying. Spray the can of white paint around the stencil. Wait for 10 mins for it dry.

Step 5 - Paint the inner bit black

Using the ring stencil, spray the inside black – being careful not to get any drips / spray on to the outer white bit. Wait for 10 mins for it to dry

(3) Cutting and finishing

Step 6 - Cutting the hardboard

Using a very sharp knife cut the hardboard along the outer edge of the ring stencil. The hardboard is pretty hard to cut with the knife - If you are not comfortable using the knife, then get an adult to help. If you are using a thicker material (such as plywood), then you are better off using a Jigsaw - as you will get a much better finish.

Place the painted circular hardboard on a piece of wood so the edges will be raised Glue it so it is firm and solid. Leave for another 2 hours for the paint to harden and the glue to dry.

You are now ready to have some fun with your sumo robots:

Guy Fawkes robot

noreply@blogger.com (BlueToothKiwi) — Thu, 29 Nov 2007 21:46:00 +0000

The military has been using robots for bomb disposals for many years now. Most of them are remote controlled.
However, lately there has been development of more specialised and autonomous EOD (Explosive Ordnance Disposal) robots that do risky operations that human beings don’t need to risk their lives for. I always wanted to design a robot that did something that is too risky for humans – and thus potentially save lives.

So early this month when we had Guy Fawkes night, I decided to use a robot based on my MINDSTORMS NXT to light our fireworks. There has been a lot of concern lately about fireworks maiming and injuring the person igniting it and a few cases of fatalities. So I thought it would be a good idea.

This autonomous NXT robot will light multiple fireworks in a sequence - while the family sits back and watch the display! The robot is incredibly simple - It uses a MINDSTORMS NXT, two light sensors (one for navigation and other to detect a lighted fuse) and an Ultrasonic detector (to detect the top of the fireworks (and hence the height of the fireworks fuse wire) so it can adjust the torch arm height depending on the position of the fuse. It uses three motors - two for motion and the third for the torch arm elevator.

Warning: Working with fireworks is dangerous. Please exercise extreme caution.

Enjoy:

My review of HiTechnic IR-Link sensor and PF elements on BrickJournal

noreply@blogger.com (BlueToothKiwi) — Fri, 26 Oct 2007 17:39:00 +0000

If you subscribe to the 'Brick Journal' magazine, check out my review of HiTechnic IR-Link sensor and PF elements in the latest edition.

If you dont, you can still see a slightly cut down version online here

There is a really good video that goes with it that walks you through the steps. If you want to learn how to robotize your own LEGO TECHNIC creations with NXT, Power function motors and the new IR-Link, checkout the following video:

Wall-e robot made with LEGO Wins the LEGO NXTLOG Building Challenge Champion award

noreply@blogger.com (BlueToothKiwi) — Sat, 06 Oct 2007 17:52:00 +0000

Wall-e, the LEGO MINDSTORMS NXT based robot that my children and I designed and built, wins the LEGO NXTLOG Building Challenge Champion award.

The entries from all over the world were judged for having the best robot design and robot performance.

Our autonomous robot was chosen by the judges to be the best amongst entrants for the NXTLOG Back to School Building Challenge. We did not expect to win with such high standard of entries - but the children, who put a lot of hard work into it were really happy to win the Champion Award.

The robot was inspired by the new Pixar-Disney film that is coming in a year's time, WALL-E. The film is all about a clean up robot:

The story goes "WALL-E is the story of the last little robot on Earth. He is a robot that his programming was to help clean up. You see, it's set way in the future. Through rampant consumerism, the Earth was covered with trash. And to clean up, everyone had to leave Earth and set in place millions of these little robots that went around to clean up the trash and make Earth habitable again..... " according to Disney.

Here is our Wall-e in action cleaning up the litter:

For more details, check out the LEGO NXTLOG entry.

Using 'Infrared-Link' to control PF motors from MINDSTORMS NXT

noreply@blogger.com (BlueToothKiwi) — Thu, 20 Sep 2007 22:33:00 +0000

In this post I want to talk about robotizing LEGO TECHNIC creations.

The picture below shows a bulldozer 'robototized' by adding a MINDSTORMS NXT brick and a NXT IR-Link (made by HiTechnic) to a TECHNIC bulldozer 8275.

Powered by the latest LEGO Power Function motors and controlled by the NXT brick via a HiTechnic 'InfraRed Link' Sensor, the above autonomous robot has a mind of its own!

You can see it scanning the environment with the Ultrasonic sensors and then flattening anything in its path using the Ripper and the blade in the video below:

What on earth is this?

noreply@blogger.com (BlueToothKiwi) — Fri, 07 Sep 2007 21:33:00 +0000

This Bizarre looking creature was Constructed with LEGO MINDSTORMS NXT.

The three wheeled robot is extremely fast. The Windows Mobile device (the big phone shaped thing you see mounted behind the head) controls the NXT via blue tooth and provides a degree of autonomous behaviour.

Swimming Pool Insect Terminator (SPIT)

noreply@blogger.com (BlueToothKiwi) — Sat, 11 Aug 2007 01:45:00 +0000

Today I want to share with you a floating robot my children and I been designing and building over recent weeks.
Swimming Pool Insect Terminator (SPIT) is a special self powered autonamous floating robot that locates and destroys small clusters of bugs that float on the top of swimming pools.
We used LEGO MINDSTORMS to build this. LEGO TECHNIC wheels are used as floats. The only non TECHNIC part that was used in this project is a can of inspect spray.
The robot uses the light sensor to detect the presence of insect cluster while the Ultrasonic sensor is used to avoid bumping into the side of the pool by telling the steering motor to turn. When the Light sensor detects a cluster of bugs it tells a motor to push the button on a can of Insect spray. Another motor is used to power the SPIT forward. The project was a success and we learned a lot from it – though there are still a lot of room for improvements. The rest of this blog entry explains the problem and our solution in more details.

Swimming Pool floating bug clusters

One of the most irritating things about our Swimming pool is the thousands of tiny floating insects that inhabit the pool. The insects form clusters on the surface and make the pool look dirty and uninviting.
They are resistant to the chlorine in the pool-water and it is almost impossible to get rid of. Because it stays on the surface it never gets sucked into the water filter system. You can’t even scoop them with an object (such as a stick), as they simply fly back into the water as soon as you scoop them off the water. When you jump into the pool they get all over your body and it is totally gross.
So the idea was to create robot that can find the clusters on the surface, spray them with a mild insect spray that paralyzes them, and drown them with a
paddle so it can be picked up by standard pool filter.

Bug detection - Insect cluster locater

To detect the clusters of insects on the pool surface, the light sensor is used. It identifies the presence of dark patches on water under the robot. It does this by reading the optical properties of the water the robot is traveling over using the MINDSTORM light sensor.
A lot of time was spent on identifying reliable threshold that can be used to minimise false spraying caused by floating leaves and reflection on the water. A plastic case full of floating bugs was used to calibrate the threshold value of the light sensor reading to trigger the spray.The robot continually monitor the light sensor while it travels around the pool. When the reading changes to the calibrated threshold indicated by the insect cluster (the trigger point), the NXT brick drives the motor that pushes the button of the insect spray can.The ultrasonic detector is not used for the bug location - it is simply there to detect edges and thus avoiding damaging the light sensor by bumping into the side of the pools.

Insect killing subsystem

(a) Automatic Insect spraying
Once the Light sensor identifies a cluster of insects, the NXT brick tells a motor to power a push-rod forward into the spray button of the spray can nozzle. The Light sensor and the spray can nozzle are separated by 10 inches (25 cm) - which makes up for the distance traveled by the robot on the water during the delay before the spray hits the bugs on the water. It took nearly a week of trying different approaches to push the spray can button, that drives the spray nozzle. Even now it needs some improvements - the TECHNIC rods bending under load sometimes.

(b) Insect drowning
The sprayed insect clusters then have to be drowned for them to be picked up by the pool filter. This is done by the dual action of the paddle wheel. As the sprayed insect cluster floats underneath the SPIT, the paddle wheel churns the water and the half dead insects gets pushed below the waters surface so they drown.

The video below shows the spraying mechanism in action - you can see the spray can button being pressed by the MINDSTORM motor using gear wheels and worm gears:

Buoyancy and stability

(a) stability:
Considerable effort went into making the robot as stable as possible in the water. To make the floating robot stable, a double 'A' frame based structure was used to spread the weight of the MINDSTORMS NXT and the spray can and to keep the center of gravity low. It was really hard to avoid making the whole thing top heavy - as we have to protect the electronics from the splashes from the wheel and any ripples from wind / pool filter pump.

(b) Buoyancy:
As for Buoyancy, at first the SPIT was going to stay afloat with 4 rubber Lego Mindstorm wheels. However, this did not supply enough buoyancy to keep the robot above the water so another 4 TECHNIC tractor wheels were added.During pool testing we added A ribbon of Polystyrene on the two sides provide failover if the LEGO wheels fail (e.g. by letting in water whilst on water). Of course it was not necessary as the SPIT was self buoyant - thanks to the big TECHNIC tractor wheels.

Propulsion and steering

(a) Propulsion Subsystem:

After some prototyping work it was decided to use paddle wheel type propulsion – which was inspired by the old steamboat. The position of the paddle wheel is important. The traditional steamboat had the paddle wheels either on the stern or the sides. To maximise stability we positioned these wheels in the middle. This way the rotating action of the paddle wheel doubles up in aiding with the drowning of the sprayed bugs as well as powering the SPIT. We used the 4 MINDSTORMS claws as the paddle - as it gave the best trust with least splashes - and it looked cool.

(b) Steering Subsystem:
The steering is controlled by a turntable powered by a motor. The orientation of the paddle wheels is determined by the readings of the Ultrasonic sensor mounted at the front of the SPIT When the Ultrasonic sensor detects the side of the pool. It tells the motor to turn the turntable and thus make the paddle wheel pointing to a new direction until the edge is no longer in range of the sonic sensor.

You can see detailed description of the floating system / steering & propulsion system in LEGO's NXTLOG web site. Below is the animated building instructions of the steering and propulsion system.

Programing

We kept the program as simple as possible - Two parallel beams of NXT blocks looping forever - one for insect hunting /destruction; the other for navigation and propulsion.

< -- Click on the picture to see the blocks in NXT-G

Field Testing

The video below shows the maiden voyage of SPIT in our pool. It then progresses to a a film of SPIT shot at night: we found the light sensor most effective in the absence of ambient light (i.e. night time) in detecting bugs. The light sensor uses its own light (the red light you see on the front of the robot in the film). During pool testing we added more wheels and A ribbon of Polystyrene on the two sides provide failover if the LEGO wheels fail (e.g. by letting in water whilst on water). Of course it was not necessary as the SPIT was self buoyant - thanks to the big TECHNIC tractor wheels.

Whats NXT?

We had so much fun making the floating robot and and playing with the MINDSTORMS stuff in the process. What is next? The project is complete but we have already thought of many improvements including:

Better stability by using wider frame and more tractor tyres
More accurate bug cluster detection by using the colour sensor (instead of the light sensor which only works best at night)

More robust spray can button pressing mechanism based on beams rather than rods

Incorporation of a Compass sensor and GPS sensor to make the scan of the pool more efficient

Warning: If you want to attempt a project similar to this, please exercise caution to ensure that your NXT / motors and sensors are not damaged by the water.

Also it is potentially dangerous to operate an aerosol can button with a motor - be cautious.