Over the last few weeks, I have been adding content about the latest features of NXT-G 2.0 (The programming software shipped with NXT 2.0), showing off the latest additions, and explaining differences in file content, etc. Here is a brief index of the latest posts:
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One of the most frustrating things about the Alpha Rex model instructions for the NXT 1.0 is the difficulty in changing the battery - without partially taking apart the AlphaRex torso.
LinearActuator had tried to solve the problem by redesigning the torso of the AlphaRex so that it will work with the NXT Rechargeable battery (that is shipped with the NXT Education Kit).
The full step by step instructions can be found here:
Straight from "Indiana Jones and the Kingdom of the Crystal Skull" comes the NXT Jungle Cutter! As seen in the film, the NXT Jungle Cutter can cut down trees using its' front saw blades (Exo-Force Wheels), and crush stray branches and twigs with its' 'Grinder' mounted just above the front triangular 'shield' (See Pictures).
The NXT brick is mounted behind all of this inside the cabin of the Jungle Cutter.The NXT Jungle Cutter uses two NXT Servo Motors, as well as 2 PF Motors (One PF Motor is a dud, and is mainly a cosmetic and used to keep the model symetrical and balanced). The PF motors are connected to the NXT Brick using a converter cable that was made by cutting a PF Motor wire and a NXT cable wire in half, and then soldering them together. One PF Motor controls the front saw, and the other the Grinder mounted just above the saw.
The 'Saw' of the NXT Jungle Cutter was made using two wheels from the Exo-Force model "Mobile Devastator (Set# 8108), and is powered using one PF Large Motor (The other PF motor is a 'dud', and is used to keep the model symmetrical). As one wheel turns, powered by the PF motor, it meshes with the other wheel, allowing it to rotate as well. A castor wheel has been attached to the Exo-Force wheels to help them balance and mesh.
The Tracks of the NXT Jungle Cutter are both powered by individual Servo Motors, and are connected to the front of the model either side of the 'saw'. 
To celebrate the release of Batman’s latest film, “The Dark Knight”, the NXT BatCycle was created! Armed and dangerous, the BatCycle can handle any opponents it may encounter with its’ hidden rocket launcher that expands from the body of the bike. With its’ large wheel area, the NXT BatCycle can also stand and move unaided! (with minor turning and terrain exceptions)
The BatCycle’s documentation has been split up into four main modules, as well as a small section on the NXT BatCycle’s weapon, and how to construct the black TECHNIC panels from the TECHNIC Tow Truck (Set No. 8285). An .LXF file of the basic construction of the BatCycle as well as a basic program, have also been provided on the NXTLog page for this model.
The results of the NXT NXT competition are in... and the NXT Whac-A-Mole recieved the creative use of NXTlog award! Here are the judge's comments:
For the latest NXT competition, we designed a NXT Whac-A-Mole, just like the machine most commonly found in carnivals, but with the added inteligence of a NXT brick!
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.
Robot sumo is one of the fastest growing sports around. Now if you own a LEGO MINDSTORMS NXT, you can join in as well:
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.
You are now ready to have some fun with your sumo robots:
Wall-e, the LEGO MINDSTORMS NXT based robot that my children and I designed and built, wins the LEGO NXTLOG Building Challenge Champion award.
Today I want to share with you a floating robot my children and I been designing and building over recent weeks.
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.
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.
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.
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.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.
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:
Well! I got myself a free Blog account at last. I have even given it a name. And the whole world can see my blog in blogspot.com. As of today, I am officially a blogger!
What now? I have no idea how to create a Blog. So I decided to investigate further to see what is available – starting with what Google Blogger / BlogsSpot provided:
I did a simple blog entry today using the Google Blogger’s built in HTML post screen:
However, having used to working in smart client applications with rich functionality, I was struggling to get used to using the Web based editor. Where is my spell checker? Where is my auto correct? Where is my grammar checker? What about all the cool formatting I am used to in Microsoft Word? Why can’t I paste an image instead of first having to upload it first ? and so on...
Coming from a software background, my immediate answer to my above problems was to write my own content management system for Google Blogger that I could use from my Desktop. I used the .Net version of Google Blogger data API’s to do just that. This was easier than I thought... it was just a matter of downloading the Google API client library, a few lines of .Net code to authenticate and a few lines of code (see below) to submit the entry:
AtomEntry newPost = new AtomEntry();
newPost.Title.Text = "My first ever Blog post !!";
newPost.Content = new AtomContent();
newPost.Content.Content = "<div xmlns='http://www.w3.org/1999/xhtml'>" +
"<p>Woooo hooo. At last. I got my self a blog. Stay tuned for " +
" some really cool posts coming here relating to the stuff " +
" me and family get up to, my thoughts etc.</p>" + "</div>";
newPost.Content.Type = "xhtml";
newPost.Authors.Add(new AtomPerson());
newPost.Authors[0].Name = "BlueToothKiwi";
newPost.Authors[0].Email = "BlueToothKiwi@somedomain.com";
AtomEntry createdEntry = service.Insert("http://www.blogger.com/feeds/"
+ "BlueToothKiwi/posts/default", newPost);
But the thought of writing my own fully fledged CMS in 3 hours seemed a bit daunting – so I carried on exploring:
I wanted to explore the option of posting directly from Microsoft Word 2007. After playing with Word 2007, I found a ‘New blog Post’ option under new document on the main menu:
Pressing ‘Create’ gives you a choice of Blogging providers to choose from (including the Google Blogger):
Then there was a simple login screen to connect to the blogger. The Office dialog came back with a list of all my Blogs on blogspot.com to connect to – very impressive!!
Once you have completed editing your post, submitting is as easy as pressing the ‘Publish’ button:
I logged on to my blogger and checked out my posts to see if the post from Word 2007 made it. And sure enough it was there on the list of posts!! I was very impressed by now. A quick examination of the source showed it was OK’ish HTML:
<div class='post-body entry-content'>
<p><span xmlns=''><p style='text-align: center'><span style='color:#333333; font-family:Verdana; font-size:12pt'>Woooo hooo. At last. I got my self a blog. Stay tuned for some really cool posts coming here relating to the stuff me and family get up to, my thoughts etc.<br /></span></p></span></p>
<div style='clear: both;'></div>
</div>
However, I could not get the images to upload automatically from Word. It looks like Microsoft did not implement the Blogger’s image interface – so the only option I had was to upload it to my own server – which was not what I wanted:
I looked at various options – the best option was to use a free Photo album store on the net and use Word to embed the images. I looked at various options including MySpace and Google’s Picasa Photo Album. I was pretty surprised to find all my pictures I uploaded from the blogger account in the Picasa photo store! I figured out that both Blogger and Picasa used the same image store on the Google server!
Google Picasa was pretty easy to use – and I could use the same Google Login I created for the blogging to create an Album and upload my pictures.
The ‘link this photo’ option gave me the link to the photo on the Picasa photo store. I copied the link URL, cleaned it up and embedded the simple URL in the Word document as an HTML <img> tag..
The Category / Label button on Word was disabled – so I could not set it. And even more disappointing was when you published the content, Word automatically stripped the pictures. I decided that I could not use the Word option until we have direct picture publishing capability directly from Word 2007 into the Blogger image store.
After the partial success with direct publishing with Word 2007, I realised I needed an alternate strategy. I still wanted to stay with Word 2007 for editing – but find a way of retaining the images. I can live with putting the YouTube videos manually after the post.
So I saved the blog I created in (3) above in Word 97-2003 compatibility format (The new MS Word 2007 Docx format is not yet supported by Google) and uploaded it into my doc store in my Google ‘Docs and Spreadsheets’. The upload and conversion takes a few seconds.
Once you have published on the doc & spreasheet repository and have checked the conversion from Word format to HTML, you are ready to upload it to your Blog.
Before you can do that, you need to configure the Blog site settings (username / Blog name and password).
As long as you got a Word style of H1 heading applied to the main title in the original document, the converter retains the heading as the title and will be used as the title of the post. I have not figured out how to use Label / Category tags yet. The upload wizard did a pretty good job of converting the Word document into HTML – I was extremely impressed.
The thing that most impresses me about Google Docs and Spreadsheet is that you can actually email it to special email address they give you (with a complex address so no one else can use it). You can use this as a quick way to get a whole bunch of documents online at one time – with each attached document will be converted to HTML and appear as a separate document. .. And the title of each document will be the file name of each attachment.
So now that I got the blogging sorted, you would be seeing more blogs from me hopefully!
P.S. This blog was created in Word 2007, published using Google Docs and Spreadsheets without any edits in here.
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