Superpositioned: Tag lego

Another RCX-based balancer

Matthew — Mon, 13 Nov 2006 08:38:00 -0800

I’m a sucker for interesting robots. Especially if they are built out of Legos. Everybody loves the Legway, but you have to admit that the concept is overly simplistic. The real challenge is building the system around the limited resources of Lego’s RCX.

Now meet another balancing robot courtesy of Maurits Kooiman on Lugnet. This one balances on one wheel and apparently uses two RCX bricks and four sensors along with three tires to maintain balance on the axis perpendicular to its unicycle. The robot balances on the main axis by directly powering the wheel. The axis perpendicular to its unicycle is balanced by the set of rotating tires. The fourth tire seems to be a freely swingy pendulum, but it may in fact be controlled by yet another motor. Check out the video!

Nic_1: Sound following robot

Matthew — Fri, 10 Feb 2006 07:01:00 -0800

There are a lot of LEGO Mindstorms robots out there, but I finally found the best. Nic_1 is a Johnny V impersonator that detects the direction of sound and follows it. Detection is accomplished by calculating the cross-correlation of two audio signals from the binaural sensor. The data is used to estimate the phase difference between the them. (Videos tracking Kelly Clarkson included!)

I can’t wait any longer for LEGO Mindstorms NXT in August. 32 bits, servos, and mics, oh my!

DIY Lie detectors

Matthew — Fri, 20 Jan 2006 06:10:00 -0800

Makezine recently posted a diy lie detector kit that uses your skin resistance (aka sweat) to detect a lie. The kit is well explained and consists of two probes you place on your palm with a red/green led readout.

Multimeter based feedback

This is all well and good, but sometimes a little more feedback is a bit more intuitive. We are trying to learn here.

Some time ago, Jason Bradbury created his own lie detector using only a resistor, a transistor, an led, and a multimeter. The led lights up if you are lying, but the multimeter provides more precise feedback of the skin’s resistance.

If you are really desperate, you can just clip the leads of your multimeter straight to your subjects palm. The ‘scary’ device may cause them to sweat and ruin the experiment, though. Just don’t tell your girlfriend you will shock her if she does not love you.

Finger straps and the LEGO RCX

The galvanic skin response sensor uses a LEGO RCX brick to detect lies and also has numeric feedback. The finger straps are the best part of this project. Your subject will know you mean business when you clip these puppies to your multimeter.

Mechanical logic gates

Matthew — Fri, 13 Jan 2006 18:17:00 -0800

A few people have designed boolean logic devices using LEGO pneumatics… I had suspected that there would be a large number of logic devices using mechanic principals, but a search for mechanical logic devices didn’t get many hits.

He decided to take matters into his own hands and design mechanical LEGO logic gates. A clockwise rotation represents a binary “one” while a counter-clockwise rotation represents a binary “zero.” The AND gate seems to require less pieces than a NAND gate, contrary to transistor design.

Unfortunately, he failed to implement an XOR gate. I wonder if it would require a more complex mechanical design (contrary to its simple transistor layout.) Kudos to the first person who implements a 16-bit binary adder with a Manchester carry chain using LEGO! VLSI is not my strong point.

Mindstorms NXT poised for hacking

Matthew — Thu, 05 Jan 2006 10:18:00 -0800

I am a huge fan of the original LEGO® Minstorms™. The platform seems to be dead lately, in spite of the FIRST LEGO® League and ongoing hacks of the RCX. Personally, building custom sensors and hacking on BrickOS were the only things that attracted me. The standard components and programming enviroment were better suited for children, but too complex and boring to keep their attention.

However, LEGO® Mindstorms™ NXT is poised change everything and bring the joy of hacking to less experienced LEGO® users through 3rd party support! Everything has been revamped and a team of four major Mindstorms™ community members contributed to the new design. NXT corrects several major downfalls and encourages hacking.

A new intelligent brick and microprocessor

The original RCX was an ugly yellow brick with a slow 16-bit microprocessor. LEGO® Mindstorms™ NXT includes a brand new brain based on a 32-bit microprocessor. I’m sure that modern technology has also made the processor significantly faster. Say goodbye to integer overflows and hundred clock-cycle calculations! The NXT also has more memory. Hopefully there is enough to bring significant amount of logged data home.

There is a large dot matrix display and “real” speaker. Spectrum analyzer? Voice recording and playback? Will the processor be powerful enough to decode mp3s?

The NXT has three motor outputs similar to its younger cousin. LEGO® has included four sensor inputs, though. If you take a close look at the brick, then you will see input 4 is not labeled. Originally I thought this was the only input that supported active sensors, but the light sensor seems to be active as well. Any ideas?

Three servo motors

Three whole motors this time! These motors are the real deal. They feature embedded rotation sensors with 1 degree precision. This means no more attempts at forcing higher precision on the stock rotation sensor through gear ratios! (Or build compatible sensors with better precision or a high precision angle sensor). Hopefully, these motors will allow direct access to rotation information and function as unpowered rotation sensors as well.

Better sensors

The NXT includes the usual touch and light sensors. It also sports a microphone sensor. The ultimate accessory is the ultrasonic sensor. Finally LEGO® has provided us with a reliable way to measure distance.

SNOT Design

SNOT stands for studs not on top. With the RCX, you are forced to lock the RCX in place using the standard LEGO® studs. This made it impossible to change the batteries and difficult to reach the buttons. With NXT and SNOT, the technic-style connections are significantly stronger and leave more of the NXT brick exposed.

6-wire RJ11 type digital input/outputs

Ever try to make a LEGO® wire connector thingy? Ever to try to solder something to the standard braided LEGO® wires? Trust me it is not easy. With the NXT, LEGO® used standard RJ11 connectors. This should make custom sensors much, much easier! In fact, LEGO® is encouraging 3rd party sensors.

LabVIEW

National Instruments’ LabVIEW is a development environment used by professionals. Personally, I have used LabVIEW in several electrical engineering lab projects and interviewed at several companies that use LabVIEW to program custom robotics equipment.

LabVIEW is also the heart of NXT. It is a block-diagram based programming environment similar to the original Mindstorms programming environment. However, it should allow for custom blocks and low-level access. LEGO® could in fact lock these features, but they will be necessary for 3rd party sensors. Custom blocks would also allow younger generations to benefit from advanced DSP or control system code designed by experienced engineers.

Bluetooth

Ever play with one of Sony’s bluetooth racers or control iTunes from your cell-phone? Giving your robot commands from your cell-phone or pda will be more fun and much geekier. It’s time to find my bluetooth dongle.

Price

Again, LEGO® Mindstorms™ will be the cheapest, most functional robotics kit available. No other kit has “back-emf” motors, bluetooth, and sonar for $250USD.

Community

The Mindstorms™ community today is fairly dispersed about the Internet. The only real colaboration is FIRST. Online communities today are much stronger, and this gives LEGO® a second chance to develop something great.

Linux Support?

Mac OSX is supported, but Linux seems to be left out. LabVIEW works in Linux and hopefully a driver/software port will not be too difficult.

Either way I am sure going to lose hairs on this. Hopefully the Linux community can work something out.

Hacking LEGO® Mindstorms™ NXT

As you can see, LEGO® has done a much better job of satisfying Mindstorms’ wide variety of users. They have released a call for 100 great developers. The chosen few will have access to the NXT platform six months before its final release. I have applied and can always hope. If I am not chosen, the LEGO® MINDSTORMS™ Users Panel better have some interesting hacks started by August of 2006.

Jason Calacanis’ CES 2006 Photos

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News Releases

Square Lego wheels

Matthew — Sat, 31 Dec 2005 19:39:00 -0800

The Troy, NY company that invented a mechanism for powering a vehicle with square wheels has been all over the web lately. Their idea is obvious, but ingenious. The square wheels are turned by a rotating mass mounted atop the vehicle. Everything is angled precisely causing each wheel to successively roll flat as the mass rotates around the vehicle.

Several LEGO maniacs decided to try this on their own. (Video included in the first link.) The results are simple and successful.

Philo’s Solution (with video)

Alexander’s Solution