Servo - September 2011

Going Further With The Beginner Bot

Yesterday’s robots can teach us a lot about today’s robots. That’s because old school bots used simpler ways to control them. It was easier to understand what was happening, thanks to their reliance on simple circuits. You could see how the wires connected from one point to the next, and visualize how the juice from a battery turned on this component, or switched off another.

There’s no need to stock up on tubes and giant relays ... we don’t need to go that far back in history! If you’d like to step into the world of smart robotics, however, a great way is to learn how to build a no-frills, no-brain mechanical pet that uses basic electronic parts to move around the floor.

What’s even better is the parts for your bot can be repurposed when you’re ready to move to the next step.

Part 2

by Gordon McComb

www.servomagazine.com/index.php?/magazine/ article/september2011_McComb

That’s the idea of the Beginner Bot, introduced last month. In Part 1, we discussed how to construct the Beginner Bot using common materials like plywood or sheet plastic. We also discovered how to drive and steer our bot by using a pair of mechanical switches.

This time, we’ll go to the next level. We’ll replace the manual switch control with fully automatic — yet simple — electronic function. Our robot will react to light, coming toward any bright light source.

Using just a flashlight, you’ll be able to lead your robot around a darkened room. (Yeah, I know I was going to demonstrate tactile feedback this time around, but I’m going to save that for a future installment.) Figure 1 shows the completed Phase 2 Beginner Bot — all ready to be guided by nothing more than photons.

Remember that the techniques you’ll learn here — and even the components you’ll use — will be applied in upcoming episodes of the Beginner Bot series.

Using Electronic Motor Control

Mechanical switches help demonstrate how to control the motors of a robot. As you discovered in Part 1, motor direction is controlled by alternating the polarity of the current applied to the motor’s terminals. A double-pole, double-throw (DPDT) switch is a great demonstrator of robot motor control.

A manually controlled robot is nothing more than a fancy toy; it’s not a true robot until it can run on its own. Through electronic control, you can replace the switches with