Content in “Lego”

Mr. Chair Challenger

jip — Sat, 15 Mar 2008 17:39:54 +0100

Primary image

What does it do?

Goes around the four legs of a chair to meet the chair challenge

Here is the program for the robot :-)

Since it just uses its encoders to do the moving it will drift over time as you can see in the video...

- Jimmy

Cost to build

Embedded video

Finished project

Complete

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Time to build

Type

URL to more information

Weight

PICAXE Pete

jip — Fri, 08 Feb 2008 15:33:57 +0100

Primary image

What does it do?

Since this project is not finished yet the robot just sits there for now...

Most of the LEGO platform used for this robot was used in DTU RoboCup 2006.

PICAXE Pete is my first time using the PICAXE controller.

The robot has a homemade line sensor using light dependent resistors (LDRs) and a homemade PICAXE-board with an L293 driver chip as well (see picture).

It can either connect to a single 7,2 V pack og two of these in serial (for giving the motors more power).

Power to the chips and line sensor is regulated by an LM7805 voltage regulator with some bulk capacitors. Of course the PICAXE board also has a means of connecting the programmer cable to the board for programming the PICAXE chip.

I took the robot apart and took some pictures while putting it back together - just so you can see how it's made. I think the design is rather nice actually :-)

First of all there is the "engine block":

Then there is the "tail section":

These two are then put together:

(Disregard those grey 1x4 plates in the left side of the picture. They're a leftover from some strange idea I had. Next image shows some added axles for the active wheels (notice they run through the rotation sensors - they're the blue ones in case you wondered). There's also been added some things at the front for the line sensor:

Then finally the active wheels (from the Technics Super Car set) are added and the vehicle is finished:

A look from the rear:

This is kind of an expensive construction since it uses bricks from a MINDSTORMS 2.0 set, a Technics Super Car set and two separately purchased LEGO rotation sensors (they are NOT cheap!). Anyway I like this vehicle!

With line sensor, controller board and batteries the whole thing looks like this:

It's not really the prettiest robot in the world :-).

Cost to build

Embedded video

Finished project

Number

Time to build

Type

wheels

URL to more information

Weight

NXT Line Follower

jip — Tue, 05 Feb 2008 19:55:16 +0100

Primary image

What does it do?

Smoothly follows a black line

The robot measures line position with the 4 line sensors and feeds this to a PD-regulator which in turn produces the two motor outputs. This setup gives a smooth line following.

The cost of the robot is roughly the cost of a set of MINDSTORMS NXT + 3 additional NXT light sensors and the rechargeable battery.

The time to build includes several mutations of the basic design - time flies when you play with LEGO ;-). Of course some time was spent finding some usable values for the P and D constants for the PD-regulation.

I used the Bricxcc IDE for developing the controller program.

Cost to build

$650

Embedded video

Finished project

Number

Time to build

5 hours

Type

URL to more information

http://defiant.dk/movies/nxt-robot2.mov

Weight

722 grams