Exotic timepieces of all stripes have always fascinated me, from water-powered clocks to the massive type that serves as an integral part of building architecture. Rolling ball clocks have also piqued my interest, hence this post about Philippe (“Philo”) Hurbain’s RCX-powered rolling ball clock, based on an original design by Bob Kojima.
Powered by a single RCX 1.0 (w/AC power) and equipped with a number of tiny LEGO balls (see below), this contraption can keep track of time thanks to some custom NQC programming and an elegantly-designed 8-bucket ball elevator. On his website Philo explains how he surmounted one challenge — an overly speedy RCX processor — with some custom NQC code:
The problem should have been very simple: each minute, start the elevator until a ball is detected by one sensor. Unfortunately, my first try over a several hours period showed me that my clock was fast, several seconds each hour! After eliminating all mechanical possibilities (two balls at a time, or an undetected ball), I concluded that my RCX itself was fast… To make sure, I finally put a frequency meter probe on RCX crystal, and indeed it oscillates at 16.03 MHz instead of 16.00 MHz. So I finally added some code to wait for 6.92 seconds each hour.
Check out Philo’s complete web page for more details on how he modified the design to overcome other challenges, along with some useful links and other info. (Source: LUGNET, Philohome : Images (c) Philippe Hurbain) – [Jeff James]
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Everyone loves to see a giant row of dominos getting knocked over in perfect sequence, with lines of the falling tiles snaking off into every direction. Everyone loves to see the finale, but what about all the hard work that went in to lining up thousands of those blasted little things? Robot builder Dave Astolfo came up with a solution: the RCX-powered DominoBot.
Astolfo explains on his website that some aspects of the build were particularly challenging, especially coordinating the actions of the three motors to properly place the dominos on their edges:
“Without giving away too much, DominoBot consists of sub-sections that are built seperately and the combined into the final model. The biggest challenge that I faced was using three motors to drive, steer, and lay the dominos. I met that challenge with the Loader mechanism (seen below), which has the ability of dispensing and placing each domino with one motor and sensor.”
The original DominoBot took Astolfo rough 20 hours of testing and experimentation to complete the build, as well as additional time to create the building instructions. Astolfo’s creation was featured as one of 10 Mindstorms robots featured in the LEGO Mindstorms Ultimate Builder Projects book by Syngress Publishing.
An updated version of DominoBot based on the new Mindstorms NXT (DominoBotNXT) has been created by Astolfo as well. (Source: Dave Astolfo) – [Jeff James]
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Having spent a winter or two during my youth in the 1980’s trying — mostly unsuccessfully — to solve that brightly-colored bundle of endless frustration and obsession known as the Rubik’s Cube, I eventually gave up and moved on to other puzzling pursuits. Frustration with inanimate objects becomes me, I guess.
Close to 20 years later, JP Brown has managed to create arguably one of the most impressive Mindstorms creations ever — an RCX-powered Rubik’s Cube solver. Using a pair of RCX units, a Mindstorms Vision Command camera, a few grabber arms and an extensive amount of custom programming, Brown’s creation can methodically grasp and turn the cube until it is solved.
As he explains on his website, Brown admits that one of the more time-consuming aspects of the project was writing the color recognition software that helped determine which way the grabber arms needed to move. Working in conjunction with the color recognition software is the 3×3 Rubik’s Cube solver code (adapted from some existing code) that is based on a cube-solving solution developed by Herbert Kociemba.
A project page on Brown’s site provides a detailed overview of the project, including code downloads and other details. (Source: JP Brown, images copyright JP Brown) – [Jeff James]
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We’ve chosen one of the more ambitous projects we’ve received to kick-off our coverage of old school (pre-NXT) Mindstorms creations: an RCX-powered, full-size pinball machine!
Designed and built by Gerrit Bronsveld and Martijn Boogaarts, this fully functional pinball machine boasts a number of novel features, including a working coin slot (50 cent Euro coins only, please!), a functional tilt switch (to detect table movement), rotation bumpers (to generate extra ball speed) and an automatic ball-kickback mechanism. Thirteen RCX units were used to control all of the board functions, driven by custom programs written using the alternate NQC (Not Quite C) programming language.
Gerrit and Martijn used more than 20,000 LEGO bricks in their creation, along with an equally impressive number of other elements:
- 50 lamps (34 used for “Pinball” display alone)
- 24 motors
- 8 light sensors
- 13 rotation sensors
- 18 touch sensors
The pinball machine is not only functional, but has endured the hands-on attention of thousands of fans at a recent LEGO event held in Zwolle, Netherlands, that attracted more than 48000 visitors in 6 days. Impressive stuff indeed.
Check out more photos of the device at either Gerrit’s or Martijn’s Brickshelf sites, peruse an in-depth feature over at Pinball News, or download a fact sheet (Microsoft Word Format) here.
Have a cool RCX-powered old school creation you’d like to tell us about? Drop me a note at jeff [@] nxtbot.com! – [Jeff James]
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