Nuts and Volts - July 2010

Experiments with Alternative Energy

Part 12 - Build the Telematics Car

By John Gavlik, WA6ZOK

Telematics is the twenty-first century word for “telemetry” which was coined somewhere around the mid-1950s, to mean wirelessly transmitting data from one point to another — usually from a moving vehicle like a car, plane, or spacecraft to a ground station. These days, telematics is an entire industry generally focused on modern automobiles that wish to be “always connected” to where they are and where they are going. GM’s OnStar™ is one example, as is FordSYNC™ that purport to keep you in touch with your vehicle as you drive — as well as the environment in which you’re driving — with things like GPS voice activation, accident detection, directions to the next filling station or restaurant, etc.

Figure 1. The Telematics Car.

So, what does any of this have to do with fuel cells? The answer is that we are about to equip our [already spectacular] fuel cell powered Hydrocar with telematics capabilities. That is, we will equip it so that it wirelessly transmits the Hydrocar’s electric motor parameters to your computer as it moves; this will include [the measure of] the voltage, current, motor resistance, and power wirelessly transmitted in real time to your computer. That way, you can see exactly how the car’s motor and fuel cell react when it starts, stops, moves forward, reverse, and up hills and down. Our telematics circuitry will transform a toy into an intelligent teaching tool (Figure 1).

ZigBee® and XBEE®

To do this, we will employ a relatively new and powerful wireless technology called ZigBee (formally known as IEEE 802.15.4) that does the hard work of taking in RS-232 type serial data in one module mounted on the car and wirelessly sending it to a receiving module connected to your computer — all without interference and special protocols that are the norm with standard RF methods (like some of the popular 400 MHz and 900 MHz radios). To make matters even better, companies like Digi International (formally Maxstream) have created plug-in modules they call XBEE that contain the ZigBee circuitry plus an antenna. Just add + 3. 3 volts and a connection to the RS-232 source and you’re in business (see sidebar).