Wishful Coding

I found a video that features a skating robot, it moves, but skating? I did a lot of skating myself, so I started to think about a better skating movement.

It occurred to me that while skating around pylons, you don’t need to take your skates of the ground. What you do instead is hard to explain.

I tried to explain my idea to anyone who’d listen in #mindboards, but to no avail. You just have to see it with your own eyes.

It is a really fun thing to build and play around with. I suspect you can find more efficient and inexplicable ways to move and turn.

Get the building instructions for this model

This is the Mirah code I used in the video:

import lejos.nxt.Motor
import lejos.nxt.Button

def align()
	Motor.A.rotate(360 - (Motor.A.getTachoCount() % 360))
	Motor.C.rotate(360 - (Motor.C.getTachoCount() % 360))
end

speed = 150
Motor.A.setSpeed(speed)
Motor.C.setSpeed(speed)

Motor.A.forward()
Motor.C.forward()

Thread.sleep(20000)

Motor.A.stop()
Motor.C.stop()

align()

Motor.A.backward()
Motor.C.forward()

Thread.sleep(20000)

align()

Motor.A.forward()
Motor.C.forward()

Button.waitForAnyPress()

I am going to attend Hacker School this summer. While I will fill half of my suitcase with LEGO, I won’t be posting regularly.

With that said, I hope there will be some exciting projects I can share with you. Have a great summer… or winter!

I’m working on a few things that require a bit more code that what I’ve done so far, but I find it to cumbersome to write so much code using NBC, NXC or NXT-G. Then I found Lejos.

Lejos is a Java Virtual Machine for the NXT, and it replaces the standard firmware. While Java is a marginally nicer language, the major win is in the packages.

Lejos comes with a lot of packages that contain useful code for doing common things, neatly organized by names like lejos.navigation.Navigator or java.util.Map.

The only problem with Java is that it’s verbose. Compare a simple program that prints “Hello world!” written in Ruby, and in Java.

You might wonder why Ruby is suddenly involved. It’s because of Mirah, which is Ruby syntax for Java classes. You could thus run the linked Ruby code, but you are actually using java.lang.System.out.println.

This means that if you need to know how to write something, google for the Ruby solution. If you want to know which classes to use, look for the Java solution. (classes are like hierarchical  collections of words, more on that later)

To make this all work with the NXT, you first need to instal Lejos.

To install Mirah, you also need to install jRuby, afterwards you can just run

jruby -S gem install mirah

Stay tuned for for some Mirah code for the NXT. I might also tell you more about classes.