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The Control car is the central nervous system of the UNSW SRT when the car is on the road. It contains quite an impressive inventory of electronic gear, from inverters (to convert 12 volt dc to 240 volt ac) and batteries to wireless GPS units and satellite telephones. Luke MacPhearson gave me a tour of the Control car setup.
The purpose of the Control car electronics systems is to give the strategy team as much useful information as possible to allow them to make better racing decisions. The solar racing car contains the data collecting part of the telemetry system, which gathers information regarding the state of the batteries, array, motor, etc. The rest of the telemetry system is contained in the Control car. The solar car and the Control car communicate via a wireless Ethernet connection, allowing high speed two way communications between the two vehicles.
The Control car also has an internal Ethernet network connecting the wireless link to a desktop PC, and up to three notebook computers, which are used by the control car's passengers to collect and analyse data and run prediction software. The desktop PC runs Debian Linux and acts as the telemetry server.
The telemetry server is also connected to a 11 channel ADC (analog to digital converter), allowing us to monitor the output of several reference solar cells which are mounted to the Control car, for example. The Control car also houses a 12 channel GPS receiver which communicates with the telemetry server via the the NMEA protocol, giving us accurate latitude longitude, altitude co-ordinates, as well as time and sunset/sunrise predictions.
The telemetry server can also act as a mobile internet gateway, on both terrestrial GSM networks and the Iridium satellite network. This allows us to connect to the internet at any time, and while mobile, in order to obtain new information for team strategy, such as weather data. The support car has a Motorola Iridium satellite phone which is used for both voice and data communications, and an Ericsson GlobalStar satellite phone used for voice communications, when GSM and CDMA networks are unavailable.
All six cars in the fleet are fitted with CB radios for the communication of instructions and strategy between team cars. The Control and solar cars are fitted with both AM and FM CB radios, with spares available in the event of failure. As such, the support car is fitted with several antennae, including CB, iridium, GPS and wireless Ethernet. Because the support car travels behind the solar car at all times during the race, the support car utilises a directional antenna which faces forward in order to improve the range of the wireless Ethernet.
The Control car's systems are powered by a variety of means, however power is ultimately derived from the vehicles alternator. Where possible, systems are powered from 12 volts or via DC-DC converters, however for convenience, some systems are powered from a 750 watt inverter, which supplies 240 volts the systems that require it. In order to avoid flattening the car's battery while the engine is switched off, the telemetry can be powered by four 12-volt, sealed lead-acid batteries located underneath the inverter, which are charged by the alternator while the car's engine is running.
Of course, all cars are fitted with portable car-CD players and a fresh supply of CDs for entertainment.
Willy The Whale
Willy!
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