Carpet Crawler

by Trenton Henry

07/15/99

Overview

This robot was an experiment using new motors, new motor driver chips, and a new chassis.

Mechanical

I basically built a minimal chassis consisting of two Lego micro motors, a brick, an axle brick, and four wheels.

Motors

The Lego "Micro Motor" is about the size of a 4 bump Lego cube. It draws 10 ma at 30 rpm with no load, and about 30 ma at about 20 rpm with a load. It runs on around 2v (though with little power or speed) up to 9v.

Electronics

I used a 6v lithium camera battery. It is actually two 3v cells in series. 6v is used to power the motors, and 3v is used to power the electronics. (I just used one cell for the cpu power, and both for motor power).

Processor

I used the Atmel AT90S1200A, just like Robigotchi.

Photocells

Same as Robigotchi.

Whiskers

Same as Robigotchi.

Software

Same as Robigotchi.

Trial and Error

Not much, it worked pretty well right off the line.

Conclusion

It roves around on a desktop, on carpet, and on saltillo tile. The micro motors work wonderfully. The Temic motor driver chips rule. Guitar string still makes the best whiskers. Like Robigotchi, it basically runs an incredibly long time on a single battery. All experiments were a success, and much was learned.

Parts List

(2) Lego micro motor, 4 wheels, a couple of bricks

(2) Temic/Siliconix Si9986CY

(2) CdS Photocell Had a bunch, chose the smallest ones

(2) 0.1uf cap For the photocell one-shot circuits

(1) 0.1uf cap Bypass cap for the processor

(1) Connector to act as a battery power switch

(1) Sonic rated at 3-16v, built in oscillator

(1) 6v Lithium camera battery

(1) Atmel AT90S1200a (Too many "good things" to list here)

End