Reach Out and
Touch Something
Part 2 - Integrating Touch
Sensing With Your Robot
Touch is the most basic of all senses — for humans and robots. Better yet,
adding touch to a robot is easy on the pocket book; touch sensors are among
the least costly parts you'll have to buy for your bot. For under $15, you can
equip your wandering beast with a variety of touch detection devices.
Last month, we looked at three common and inexpensive touch sensors that can be added to your obot. We discovered what they were and how they
connected to a microcontroller such as the Arduino. In this
second and last installment, you'll learn how to integrate
these sensors into a motorized robot base. Each type of
sensor detects contact with a physical object. Knowing it
has collided with something, the robot will immediately
back off and try another route.
54 SERVO 08.2012
A Basic Base for
Basic Experimenting
It's always best to start from a known. For a
demonstration robot, I'll use an ArdBot chassis from my
online store Budget Robotics (see the Sources box). The
ArdBot is an expandable two-wheeled differentially-steered
robot that uses the popular Arduino Uno (or compatible
microcontroller) as its main brain. The kit comes with body
pieces and assembly hardware only — you add your own
Arduino, batteries, continuous rotation servos, and wheels.
The ArdBot comes in two versions. The standard
ArdBot has a larger 7" round bottom; the ArdBot II has a
streamlined bottom deck. Figure 1 shows the ArdBot II.
On both versions, the motors and batteries go on the
bottom deck.
To simplify the power requirements, the ArdBot uses
separate battery supplies for the Arduino and the servos.
The Arduino is powered by a nine volt battery connected to
the power jack on the board, while the servos are powered
by their own 4 x AA pack. You can use either non-rechargeable or rechargeable AA cells. If you use
rechargeable batteries, remember that they put out a
slightly lower voltage (1.2 volts as opposed to 1.5 volts),
so the servos will run a little slower.
There's room on the top deck of the ArdBot for the
Arduino, a small mini solderless breadboard, and assorted
FIGURE 1. ArdBot expandable robot with leaf switches
attached. The easy-to-drill plastic pieces of the base allow
for easy experimentation.
