Programming NXT Robots

1. Robotics: Lego Mindstorm NXT
Stage 2: Programming

2. Time to Program!
You just built your starting robot! Congrats, now it’s
ready for action. Oh wait, it’s just sitting there isn’t it…
That’s because you didn’t give it a program yet, therefore,
it doesn’t know what to do yet!
So let’s learn how to program!

3. Change How You Think
Remember when I told you the most important thing you have
to do it change how you think?
Well now is when you learn why.
To program, you have to understand how to think like a
computer. And that’s to be able to think with algorithms,
which is the computers thought process. You take for
granted how easy it comes for people to be able to think and
then act off that impulse, so we’re going to make you do an
exercise to learn how to think like a programmed robot.

4. Stop and get programmed
We are going to put you in groups of two. One volunteer to be
the robot, the other is the programmer.
Now blindfold the volunteered robot, arrange an obstacle
course in our room, and the programmer verbally direct the
“robot” through it. (i.e.“Take 3 steps, stop, turn left 90
degrees, stop, take 4 steps, stop, etc.”)
And the robot can’t feel around, keep arms to the side.

5. What did you learn?
You probably noticed that it was harder to get around when
you couldn’t think for yourself as the robot. And if you were
the programmer, you must have had to think pretty detailed
on what directions to give and how.
That’s the point. Robots can’t think for themselves, they need
exact directions. When you program your robot you are
going to need to know where you want it to go, how far,
what direction, when to turn, when to stop, etc.

6. Programming with NXT
Now that your mindset is
in programmer mode,
let’s Mindstorm!
(corny pun)
Lucky for you, NXT
programming is not
that complicated.

7. Basics
The goal of this week is for you to learn how to program on
your own and be as creative with it as you want. So we
aren’t going to give a strict guideline on how to program
your robots, the goal is to learn the basics and program your
robot anyway you see best!
Once you start learning the basics you
might discover better ways to program
than the other teams or the instructors,
don’t hesitate to be creative.

8. Movement
You make NXT programs
like you are putting Lego
blocks together.
Movement blocks are one of
the most used actions in
programming. You can
decide what servo to
activate with them,
direction, and for what
duration. (Duration will
be important later)

9. Sound Blocks
When you activate these
blocks you can make
your robot play a sound
from the files in the
NXT programer

10. Switch
When you need to program a
function for a sensor, you use the
switch function. It allows you to
program exactly what the robot
should do if a sensor is tripped.
Example: Touch sensor trips,
program to move back 2 rotations,
then turn right, continue to next
function.

11. Wait button
The wait function is
necessary for when
you want your
robot to act until it
trips a sensor. So if
you want the robot
to act a certain way
when it trips a
certain sensor, you
will use the wait
botton.

12. Loopty Loop
Loops are very handy, they
contain a program you want to
repeat. It can repeat once until
forever if you like.

13. Stop: It has to at some point!
The most important thing you need to learn in programming is
how to stop! We don’t get paid enough to do this forever!
You will want to program
your robot to stop at some
point.
Remember that you can
program the stop function
into a loop or sensor
action.

14. Making the Distance
Remember the movement blocks? When you want to program
your robot to go a certain distance, how do you know how
long to make it run?
Well, you don’t. The fact that any robot you make can move
different than other robots means that you have to find out
how far it will go on your own.
We have a handout ready to help you write down your data.

15. The reason we suggest using “rotations” instead of “seconds” to
run the movement blocks is because it is easier to figure out
how many rotations it takes to go a certain distance. Basic
math will figure out longer distances.
 Le sg totheP g m ingHa o
t’ o ro ra m nd ut

16. Stage 3
Now that you have
collected your data on (Obstacle2)
distance, you can (Obstacle3)
(Obstacle1)
accurately program your
robotic system around
our obstacle course. The
course floor plan will
vary depending on what
location you are in, but it Start
will look something like Finish
this.

17. Competition
We will have a friendly competition to see what team has
programmed their robot with more skill. The team that
completes our course with the best time wins.
However, when the competition is complete, you can readily
get back into teams and begin to create more robotic
creations.
The point of all three stages was to teach you how to create and
program NXT robots, so be creative and have fun!

18. Additional Designs
There are some additional designs in the Lego NXT program,
but if you want to find designs off the internet go to the
following sites:
 www.nxtprograms.com
 http://www.thenxtstep.blogspot.com/
 http://www.nxtasy.org/

19. Hope You Have Fun!
Good Luck!