Power Functions Car, with a Differential & Self-centering Steering

I cannot believe the last post in this blog was more than a year ago...time really does fly. I wished everyone had a great Christmas last year & a great start this year. I had a rather long break during the Christmas holidays and as usual I spent some time to work on some Technic/Mindstorms models, so I built this:

This Power Functions car was built primarily based on Snow White by Jaeho Jung and Sariel's The Unofficial LEGO Technic Builder's Guide. The PF car is modular in design and it is basically divided into 3 main modules:

• The drive module
• The chassis
• The steering mechanism

The drive module is the same as the one designed by Jaeho Jung, with an overall gear ratio of 1 : 3.75

1 : 2.25 ratio from motor to intermediate axle

1 : 1.66 ratio from intermediate ratio to wheel axle, giving a final ratio of around 1 : 3.75

The chassis module consists of the PF battery pack and long beams for connecting the drive module and the steering module.

The steering mechanism is a little more interesting here, one of the biggest problem with the PF medium motor + rack and pinion setup is the inability of the mechanism to return the steering to the centre after turning to the right of left. So I incorporated a self-centering mechanism found in Sariel's book to see how well it works & I was surprised by the results - it worked really really well.

Self-centering steering mechanism from Sariel's book

After playing with the model for a while I decided to see if I could include a differential to the drive module to see if the handling of the car would be different compared to a solid axle and here is how it looks like,

A drive module with differential, with an overall ratio of  1 : 2.78

The underside of the chassis

The differential did improve the cornering speed somewhat, and overall both the configuration were fun to drive around with. The power functions elements that were used in the construction are,

• 1 power functions XL motor.
• 1 power functions medium motor.
• 1 power functions receiver.
• 1 power functions battery pack.
• 1 power functions remote control.

And for anyone who wants to improve their construction technique in LEGO Technic/Mindstorms, I would strongly recommend grabbing a copy of Sariel's The Unofficial LEGO Technic Builder's Guide.

FLL 2011 Food Factor Challenge (Update)

FLL 2011 Food Factor Challenge will be held this weekend. In this edition, the participants were given shorter preparation time as the competition will be held earlier. The previous editions of FLL were held after Chinese New Year.

Nevertheless, both school teams under our watch, Light Warriors (Sekolah Sri Suria) and LEGO Logic (Sekolah Sri Cahaya), are busy doing final preparation for the competition. Both teams are under pressure to produce good results at this edition of FLL. In previous edition, both teams have won Judges Award and Rising Star Award respectively. In addition, Light Warriors had also won Best Overall Robot Design Award in FLL 2009.

It is also surprising that there is little promotion effort by FLL Malaysia organizer, SASBADI. There is no link nor any information on FLL from SASBADI website. The official Malaysia FLL Facebook page is also inactive.

A "practical" robot idea you can construct with LEGO MINDSTORM - RoboShart!

Merry Christmas!

We would like to wish everyone a Merry Christmas and Happy New Year!

FLL 2011 Food Factor Challenge

FIRST LEGO League (FLL) 2011 Food Factor Challenge is confirmed!

• Date: 13 - 15 Jan 2012 (Friday - Sunday)
• Venue: Taylor's Lakeside University Campus, Subang Jaya
• Organizer: SASBADI Sdn Bhd
• Website: http://firstlegoleague.org/challenge/2011foodfactor

Note that FLL 2011 is traditionally held in USA first before Malaysia, and not held simultaneously worldwide for some reason. The challenge and topic remain the same for other countries worldwide.


Here is the Food Factor Teaser from the website that describe the challenge:

Can FIRST® LEGO® League teams improve the quality of food by finding ways to prevent food contamination?   In the 2011 Food Factor Challenge, over 200,000 9-16 year olds from over 55 countries will explore the topic of food safety and examine the possible points of contamination our food encounters – from exposure to insects and creatures, to unsterile processing and transportation, to unsanitary preparation and storage – then find ways to prevent or combat these contaminates.  In the Food Factor Challenge, teams will build, test, and program an autonomous robot using LEGO® MINDSTORMS® NXT to solve a set of Food Safety missions as well as research, develop, and share their innovative food safety solutions.  Throughout their experience, teams will operate under FLL’s signature set of Core Values.

We will be coaching two school teams for this challenge: LEGO Logic from Sekolah Seri Cahaya and Light Warriors from Sekolah Seri Suria. We wish them best of luck!

LEGO in Google NYC

Google NYC is Google's second largest office nestled among the towering skyscrapers of Manhattan. It is host to 2,500 employees, the second-largest number of Google engineers.

Google NYC is a place full of classic tech and LEGO whimsy. One entire wall in the office is devoted to LEGO art and LEGO creation. It was a struggle not to stop, stay and play.

Source: Mashable (link)

LEGO Man may be released from custody

The 45.5kg, 2.5-metre-tall mysterious Lego man that was found on a Florida beach in U.S. may soon be sprung from a holding room.

Sarasota County Sheriff Tom Knight said the Lego-man could be freed from the shed where he's been kept for two days.

The giant Lego appeared on Siesta Key beach Tuesday morning.

"No Real Than You Are" was written on its shirt, along with "Ego Leonard" and the number 8.

Local newspapers report the name "Ego Leonard" is the name of a Netherlands artist, but it was not immediately clear who was behind the work.

The story of the Lego man has gotten worldwide attention.

Knight says the Lego man is being well kept and hopes the giant fiberglass man can be placed on display somewhere in the community.


Source: The Star (link)

Giant LEGO man washes ashore on Florida beach

Police in Florida have been left baffled after an 8ft tall LEGO man turned up on a beach.

Weighing 100lb, the giant LEGO man appeared on Siesta Key beach on Tuesday morning.

Bearing the cryptic message "No Real Than You Are" across the shirt, the words “Ego Leonard” were also visible of the outsized toy replica.

  

Ego Leonard is the name of a Dutch artist, but it is unclear as to whether Leonard is behind the toy stunt or if it is the work of an imitator.

LEGOLAND officials said the LEGO man was a counterfeit and is not endorsed by the company.

The mysterious plaything will remain in the protective custody of the Sarasota County Sheriff's Office until it is claimed.

A similarly gigantic LEGO man was washed up on Brighton beach in October 2008. (link)

A giant, smiling Lego man was fished out of the sea in the Dutch resort of Zandvoort in 2008

No one knew at that time where the colourful model, with Dutch writing on, came from either.

One resident said: "It must have fallen off a boat. The children love it."




Source: Mirror UK (link)

Ping Pong Robot made in China

A robot hits back a ball at Zhejiang University in Hangzhou, east China's Zhejiang Province, Oct. 9, 2011. 

Human-like robots developed by Zhejiang University in East China made debut on Sunday. The two robots as shown can capture the track of the ball by a camera installed inside before making reactions. The robots, 160 cm tall and weighing 55 kilograms each, took the university four years to develop. The university also aims to develop robots that can do housework.

The robots are able to track the movements of a table tennis ball and play back through a motion control system equipped with a built-in camera and an intelligence processing unit.

A robot plays pingpong with a visiting journalist at Zhejiang University.

Reference: XinHuaNet (link)

Ford Explorer in LEGO!

Fancy a unique bright red Ford Explorer SUV at half of the usual weight?

Ford Motor Co. and the LEGOLAND Florida theme park has formed a partnership with unveiling of a full-scale Explorer replication with LEGO bricks. The bright red LEGOLAND Florida edition Explorer will be on display at the new 150-acre LEGOLAND them park in Winter Haven, near Orlando.

The LEGO Explorer’s debut took place at the car maker’s Chicago assembly plant, which normally turns out real Explorers.

Crafted by 22 Ford employees, the Lego Explorer is made up of 382,858 LEGO bricks. It took 2,500 hours (about three and a half months) to complete. The structure weighs 1,203 kg and is supported by a 348 kg interior aluminium base.

LEGOLAND Florida, which opens Oct. 15, is designed for kids from the age of 2 to 12 and has more than 50 family-oriented rides, shows and other attractions. The park has exhibits that use more than 50 million LEGO bricks and is divided into 10 zones with different themes.

In 2004, a life-sized LEGO replica of a Volvo XC90 was built, also for a LEGOLAND in California.

LEGO Life of George

I won RobotC 3.0 Licence giveaway!

I never win anything in my life... probably because I dont join anything :p

Anyway, today look what I won?

Haha... fine fine... it is a 1 in 3 chance in winning!

Eric

Starcraft 2 Seige Tank

It is too awesome not to blog this...

RobotC 3.0 is out

I have tried and played with RobotC 2.0.

It was simple to use as I do have a programming background. But I didn't do much with it since it is not NRC or FLL legal.

Now they have just released a new version, the RobotC 3.0.





Read a V2 -> V3 log on all the improvements (link to botbench pdf)







What I found most interesteding is the new Virtual Robots World (VRW) module look interesting, allowing users to program and simulate without actually needing a physical NXT robot. This could be great for students to practice programming at the comfort of their home.... or for those who needs a little more time at their own pace.

However the new RobotC and Virtual Robots World module does come with either an Annual license or a Perpetual license (free updates till next majar revision).


Download their free trial and give it ago.... I know I will...
[Download page here]

LEGO in Haemophilia Camp

Participants of the 3rd Asia Pacific Hemophilia Camp were creating a model building with LEGO pieces during the Asia United Challenge group games session. These young people were eager to live life their way and not let haemophilia stop them from fulfilling their ambitions.

Co-hosted by the Taiwan Haemophilia Society and Bayer HealthCare, the 3rd Asia Pacific Haemophilia Camp was held in Uni-Resort of Mawudu in Hsinchu county, Taiwan, recently. It brought together those affected by the condition, to learn and share about haemophilia, and build friendships with fellow patients. The camp also aimed to motivate, encourage and empower patients and their caregivers. Over 100 participants from Malaysia, Indonesia, Thailand, Taiwan and China attended the camp.

The camp also aimed at motivating participants to live life to the fullest. Through the “Asia United Challenge” indoor group games, they had the chance to meet and befriend many other people like themselves, all living with the disorder and making the most of life despite the condition. The campsite was transformed into a hive of activity as participants tackled challenges at each of the six games stations: LEGO-building, a musical performance, piecing together a jigsaw puzzle, decorating a giant postcard, designing an outfit and a trivia quiz plus landmark mix-and-match. The kids learned to work as a team in order to complete the tasks.

Haemophilia is a blood disorder where the blood lacks a protein and therefore cannot clot properly, leading to spontaneous or prolonged bleeding, especially in the muscles, joints and internal organs. When this happens, ugly bruises develop.

Source: The Star, 10 Aug 2011 (link)

Thermal Infrared Sensor Review (Dexter Industries Sensor)

The Thermal Infrared Sensor (TIR) is one of the latest sensor produced by Dexter Industries. It is able to measure the temperature by detecting the radiation emitting from the object. The amount of infrared radiation emitted by an object increases with temperature, thus the TIR is able to measure these emitted radiation. You should read up a little more on Thermal Imaging (Thermography) to have a better concept on how it works.

Here is a picture of a Thermal Image, captured using very expensive thermal imaging equipment, NOT our TIR sensor. However the concept is the same, it captures the emitted infrared radiation, and converts it to an image.

Here I have a simple program that takes the value from the TIR sensor and output it to the NXT display. Please note that if you are using NXT Education software, the units is in Celcius, while the NXT Retail software is in Kelvin instead.


The following is what I have tried to measure:-

• my hand/body: 33.5°C 
• 34°C when I measured my hands using a thermometer. Strange but I always assume that our body temp is 36.9°C
• my router modem: 36°C
• my laptop: 44°C (without Laptop cooler)
• ice: 1°C    

Emissivity is a measure of a material’s radiating efficiency. Theoritically only a black body will have an emissivity of 1, thus almost everything else we measure is should be less than the actual temperature as it should have a emissivity value of less than 1. Check the emissivity list here. Please note that human skin has a value of 0.99.

There is a special block that Dexter Industries have produced to modify the emissivity value for the objects that you'll be measuring.

Here I have made a very simple software to measure the temperature of objects while the vehicle is moving. I have used the Data Logging feature available from the NXT Education's software.

The above is the measured temperature when as the vehicle is moving along for 10 seconds. Any idea what is it?

It is actually the heat produced by both my legs as the vehicle is moving in front of me. The lowest point is about 26°C (ambient) and the peak temperature is about 32°C (my legs).

I have written an equivalent for those that don't own the NXT Education's software. The above NXT-G equivalent writes the temperute to a text file as the vehicle is moving across.

Here is a simple experiment that I had devised. The first cup on the left is hot water, the centre is room temperature and the last cup is actually a frozen cup of water. 

The above is the data that I have received from the text file data, and then using excel, I have plotted the data using a colour scale. Please note that the actual measured temperature of the hot water was about 75°C (using thermometer) while the ice is 1°C (using TIR on ice directly). However when measured from the side, the temperature seems to be off by almost 10°C. I'll have to check the emissivityof these plastic cup and retry the experiment.And note that the centre cup didn't show up, because it was at room temperature!

Overall the TIR sensor is pretty good and sensitive. It is able to pick up my body temperature even when the ambient is only about 5°C different within 10" of distance.


I will be posting some of the NXT-G software up in the next few days as well as do a few more experiments.

MoonBots 2011 Winner Announced

A congratulations to the MoonBots 2011 winners

• 1st Place: LegoAces
• 2nd Place: Team Just Ducky
• 3rd Place: Lunar Lords

The following was quoted from the MoonBots website on Techno Inventors, our very own Malaysian Team from Sekolah Seri Suri:-

"Techno Inventors - The I’m So Excited Award - And they just can’t hide it. If we could harness this team’s enthusiasm and energy we could solve the worlds energy crisis. Outstanding work all the way around."

You could visit Techno Inventor's website for full details of their MoonBots competition and their video page.

Here is a video of their actual mission that they did. Not the best, but given the complexity of the mission, and the limited time they had, it is job well done.

GPS Module Review (dGPS by Dexter Industries)

Are you bad with directions?
Do you constantly check-in on social networks like Facebook Places or FourSquare?
Do you have an Iphone, Android phone or any other smart phone?

Chances are, you would have already used, or own a GPS if you answered yes to any of the above.

So what can the GPS module bring to LEGO Mindstorms NXT that I couldn't already do on my Smartphone?

Well for starters, the GPS is actually quiet an advance piece of technology. By calcualting the distance to each satellites in space, it would be able to triangulate its current location. You should read more about the concepts and theories on how it actually calculates its location at the wiki site here.

However, this advance technology is no use if you don't understand or know how to utilise it.

The good thing about the getting the GPS module for the NXT Mindstorm is that, you'll have to write your own codes, rather than just downloading the apps and run it on the phone.

You'll need to know a little GPS concepts, and lots of creative ideas on how to implement or use it.

The review that I will be doing today would be based entirely on the NXT-G blocks that have been provided by Dexter Industries. In the photo above, I have both the dGPS module writting the to the NXT display, while on the right, I have HTC Desire with a GPS app, obtaining it the current location coordinates. If you are able to look closely, both of them are actually giving out different coordinates... of by a few decimal points.

View GPS for the LEGO Mindstorms NXT in a larger map

I have plotted both the coordinates on Google Maps. As you can see, both shows a different location, about 10 feet apart. Which one is more accurate? Well both is off by a little, as in one if off to the right, while the other is off to the left. I would need to check this with a few more location to determine which is the most accurate.

In the same map, I have also plotted a path that takes me around the KT town area. The path is marked in red. I have also attached the NXT-G files used to log the data, as well as a KML Path Creator at the end of this post.

You'll have to download 2 custom NXT-G Blocks available here. One you have downloaded and added it into your NXT-G software, you'll be to use it under the Advanced tab.

The first Block is the GPSRead, where it is able to extract all the information from your new dGPS module to your NXT. You could either write it to your NXT Display or even a text file on your NXT.

I have modified one of the sample codes to both display the information on the screen as well as write it to a file. When you write the coordinates to a file, with fixed interval, you'll be able to plot a path, as shown in the Google Map above (red path).

The next Block available is the NXTNavigation block. Given a destination coordinates, it will return the distance and angle to the destination from the current location. The usage is a little different from the GPSRead block, but it has it own purpose.

Overall the dGPS module is excellent. To log on to the satellites is pretty quick on a clear open sky (less than a minute), but takes up to a few minutes if it is very cloudy. The response that I am able to get, even at 1 second interval is acceptable.

I'll have to do more advance vehicle or robots to fully utilize the dGPS module's full potential.

Resources:
Download and view PDF Instructions on how to Collect and Upload data to Google Maps.
Download the NXT-G file for data logging here.
Download KML Path generator here.

dGPS Preview (Dexter Industries Sensor)

I have just received the dGPS that is made by Dexter Industries.

I have been playing over the last few days. I have been using it to collect information, that I later convert and upload directly to Google Maps

Attached here is a Google Map with me driving around the town where I stay. Used the sample codes available at Building Blocks (taken from Dexter Industries resource/downloads) and have modified it a little.

I will continue to modify the NXT-G codes, making it easier to use. Before uploading the finished NXT-G codes here.

I  am also in the middle of editing a special Excel file that will auto generate the KML file used by Google Maps. Easier to manipulate the data for upload.

I will do a full review over the next few days, completing the NXT-G codes as well as any other files created.

Stay tuned!!

Moonbots 2011 - Prototyping & Robot Design

What I love about LEGO is that, given similar (or even same) parts, the possibility to create something seems to be infinite. So many possible solution for the same task...

The following is more of a Photo blog, of our attempt to prototype and design a vehicle for our Moonbot mission.

We started off with trying 2 basic design

• Tank Track based, with 2 driving motor.
• Car Based (4 wheel) with a front steering system.

 A very quick tank track based prototype done. After a few runs over the Moonbot ridges I have deem this design a little too unstable. It couldn't get over the ridge consistently, most of the time either falling on its back before going over, or falling head first after it has gone over the ridge.

 This was one of the first car based prototype that the kids had produced for me. It worked fine and was able to traverse any flat terrain properly. However the turning circle was bad.... really bad. With this design, we too had difficulty crossing the ridge, as it is tail heavy (note the NXT is behind the back drive wheel). Told the kids to move the NXT to between the 2 drive axle, giving it better balance.

The front steering wheel mechanism is really simple (anyone knows the name of this design?). It is just motor connected directly to the steering arm. No rocket science. Simple and effective.... However this design does have a tiny flaw.... it is difficult to get a good turning accuracy, as well as the terrain and ridges sometimes pushes it out of alignment.

The driving motor is connected to the drive axle directly. This design is able to push maximum power without any gears (speed or torque design). Simple and effective. However the trade off for this design is that it doesn't allow the car to turn properly (inner wheel is slower than other wheel).

We did a redesign it and tried it with a differential drive train. It worked very well when the vehicle is on flat terrain and when it is turning. However when faced with uneven terrain as well as Moonbot ridges, sometimes when all traction was lost to 1 wheel, thus transferring all the energy to the other wheel, causing inadequate traction and power to cross the ridge.

I reckon if we could try a limited slip differential, it could work. However with complicated design, it also could mean that the vehicle could be more unreliable. We decided not to try that design and just stick with the simple design and work within the limitations.

Here is a photo of another design of our tank track based vehicle. The student added some gearing, for it to power all the drive wheels, as well as added some counter balance to the robot. It did have great torque and was able to climb over the ridge easily, however the balance was difficult to overcome, causing the vehicle to constantly fall over the ridge.

While the some of us were killing our brain cells trying to figure out the best possible design for our vehicle, other students had the opportunity to do research and prepare for their STEM out reach project. The STEM out reach is worth a whopping 40% of the total, so getting this done properly was essential to the overall score

Alright... moon moon moon.... what else do I need to know about the moon.... Google this Google that.......

We decided to add a torque (speed down) gearing to the front drive arm. This makes the turning a little more accurate (but slow reaction), at the same time making it harder for the drive arm to mis-align when it hits the ridge or the uneven terrain.

One of our first working prototype with the NXT Brain moved to the centre for better balance and a new rake style arm for grabbing the objects. We experimented with this design. It was able to move over the ridge quite consistently, however the heading direction wasn't that consistent due to the uneven ridges pushing (mis-aligning) the vehicle steering arm.

Here is another prototype of a long reach rake style arm for trying to grab the objects from a further distance. The idea is NOT to go into Cravin Crater as it would be near impossible to leave it when you are within it.

Overall over the 2 days that I spent with the kids, it was great. We had many brain storm sessions, prototyping most of the designs we wanted to try and then decided which was the one that should be used. It was good as it wasn't my duty to dictate which is the best direction of building the best vehicle but give the opportunity to the kids to prototype, trial and decide.