
2
To master a Challenge, you must follow three basic steps:
1. Construct – To start, review the Design Brief. Then gather the pieces
you need to meet the Challenge and start building. (Don’t hesitate to
customize your robot with additional parts and pieces.)
2. Program – Once your robot is built, you can program it using the
simple, but powerful, programming language included on the CD-ROM.
Your program will determine how your model reacts to its environment.
3. Test – Now it’s time to test your program and design. Once you have
downloaded your program from your PC to your RCX using the infrared
transmitter, your robot can run independent of your computer. Now let it
loose and watch what happens!
The Constructopedia™ is a building guide for the Robotics Invention
System™ that offers suggestions, hints, and tips to get you started on
the CD-ROM Challenges and robotic inventions of your own design.

PROJECT IDEAS 4
ROBO 1 6
ROBO 2 9
PATHFINDER 1 13
PATHFINDER 2 15
ACROBOT 1 17
ACROBOT 2 20
SPECIAL FEATURES
Movement 26
Sensors 28
TIPS & TRICKS 32
TOP SECRET PLANS 39
PARTS IDENTIFICATION 47
CONTENTS
PAGE
3
©
1998 The LEGO Group.
®
, ™, LEGO, MINDSTORMS, Constructopedia, RCX and the LEGO and MINDSTORMS
logos are exclusive trademarks of the LEGO Group.
ISBN 1-57056-050-1

ROBO 2
Project Ideas
PROJECT IDEAS SPECIAL FEATURES
4
4 26
ROBO 1
PATHFINDER 1
6
9
13
• Slowly moves back and forth.
• Requires one motor.
• Slowly rotates in one direction.
• Requires one motor.
• Quickly turns left and right.
• Requires two motors.
What follows are basic instructions for
building the six subassemblies associated
with the CD-ROM Challenges. The same
instructions can be used for building your
own robotic inventions.

TIPS & TRICKS TOP SECRET PLANS32 39
5
PATHFINDER 2
ACROBOT 1
15
17
• Slowly turns left and right.
• Requires two motors.
• Quickly turns left and right.
Even does “wheelies.”
• Requires two motors.
ACROBOT 2
20
• Moves fast and flips
upside down.
• Requires two motors.

Robo 1
PROJECT IDEAS SPECIAL FEATURES
6
4 26
To get started on Robo 1, follow these five steps.
For this step, you need:
Put the
8-tooth gear
on the motor.
Put the
bushings
here.
For this step, you need:
To measure an axle,
see page 37.
Bushing
24-tooth crown gear
Push the 24-tooth
crown gear onto
the axle.
8-tooth gear
Motor
2 x 6 plate
with holes
Put the motor on
the 2 x 6 plate
with holes.
Attach this to the previous step.
Push the wire into
the groove.
4x means you
need 4 of these.
!
BEFORE YOU GET STARTED...
Make sure there are batteries in your RCX. For help installing batteries, turn to page 38.

TIPS & TRICKS TOP SECRET PLANS32 39
7
For this step, you need:
For this step, you need:
Dark gray connector peg
Put the beams on the
RCX using the dark gray
connector pegs.
Do this first!
Put the 2 x 6 plate
with holes here.
Connector peg with axle
Put the
connector peg
with axle here.
2 x 6 plate
with holes

PROJECT IDEAS SPECIAL FEATURES
8
4 26
Attach the end of the
wire to port “A”.
HINT: Try
this wheel.
HINT: Try
this wheel.
IF YOU NEED HELP COMPLETING YOUR ROBOT...
• Check out “Special Features” on page 26.
• Turn to “Tips and Tricks” on page 32.
TO PROGRAM YOUR INVENTION...
• Go to the MoboRobo challenge or the Robo Bumper
challenge on the CD-ROM.

Robo 2
TIPS & TRICKS TOP SECRET PLANS32 39
9
B
uild the foundation for Robo 2 by following these eight steps.
For this step, you need:
For this step, you need:
Put the 1 x 2 plates here.
1 x 2 plate
2 x 6 plate
with holes
This is the gray
connector peg.
Gray connector peg
Motor
Put the motor
onto the 2 x 6
plate with holes.
8-tooth gear
Put the 8-tooth gear
on the motor.
1x means you
need 1 of these.
!
BEFORE YOU GET STARTED...
Make sure there are batteries in your RCX. For help installing batteries, turn to page 38.

PROJECT IDEAS SPECIAL FEATURES
10
4 26
For this step, you need:
For this step, you need:
To measure an
axle, see page 37.
Push the wire into
the groove.
Put the bevel gear in place
and push the axle into it.
Do this first!
Put the bevel gear
on the differential.
Differential
Bevel gear

TIPS & TRICKS TOP SECRET PLANS32 39
11
For this step, you need:
Put the beams on the RCX using
the dark gray connector pegs.
Dark gray
connector peg
For this step, you need:
Do this first!
Put the beam here.
1 x 6 plate
Put the 1 x 6
plate here.

PROJECT IDEAS SPECIAL FEATURES
12
4 26
For this step, you need:
2 x 8 plate
with holes
Put the 2 x 8
plate with
holes here.
Make sure the
beam touches
the gear.
For this step, you need:
Bushing
Put the bushing
on the axle.
Put the beam onto the
gray connector peg.
24-tooth gear
Put the 24-tooth gear here.
HINT: Try
this wheel.
HINT: Try
this wheel.
IF YOU NEED HELP COMPLETING
YOUR ROBOT...
• Check out “Special Features” on page 26.
• Turn to “Tips and Tricks” on page 32.
TO PROGRAM YOUR INVENTION...
• Go to the Robobeeper challenge or the Robioptic challenge on the CD-ROM.

Pathfinder 1
TIPS & TRICKS TOP SECRET PLANS32 39
13
T
o start building Pathfinder 1, follow these four steps.
For this step, you need:
For this step, you need:
Skid plate
Put the skid plates here.
Inverted roof brick
Put the inverted roof bricks here.
2 x 4 plate with holes
Put the 2 x 4
plate with
holes here.
2x means
you need
2 of these.
!
BEFORE YOU GET STARTED...
Make sure there are batteries in your RCX. For help installing batteries, turn to page 38.

PROJECT IDEAS SPECIAL FEATURES
14
4 26
For this step, you need:
For this step, you need:
Put the
motor
on here.
Put the ends of
the wires here.
Motor
Put the RCX
on top.
HINT: Try
this wheel.
RCX
IF YOU NEED HELP COMPLETING
YOUR ROBOT...
• Check out “Special Features” on page 26.
• Turn to “Tips and Tricks” on page 32.
TO PROGRAM YOUR INVENTION...
• Go to the Outback Tracker challenge or the
Light Tracker challenge on the CD-ROM.

Pathfinder 2
TIPS & TRICKS TOP SECRET PLANS32 39
15
For this step, you need:
For this step, you need:
To measure
an axle, see
page 37.
Put the 1 x 2 bricks here.
1 x 2 brick
Bushing
Put the
bushings here.
4x means
you need
4 of these.
To get started on Pathfinder 2, follow these four steps.
!
BEFORE YOU GET STARTED...
Make sure there are batteries in your RCX. For help installing batteries, turn to page 38.