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BROCK'S BMW: ELECTRONICS UPDATES On October 2nd, millions of Australians will watch the motor racing at Bathurst. In particular, their eyes will be on Peter Brock and his co-drivers. Computers will be watching him too as he strives to get the very best out of his BMW M3 sedan. By LEO SIMPSON Just how do you screw the very maximum performance out of a racing sedan over a distance of 1000km without running the risk of blowing it up before the finish? That is a question which continually haunts racing drivers and their backup teams as their cars hurtle around the track. More than any other driver, Peter Brock has always managed to perform this task to the optimum. They don't call him "Peter Perfect" for nothing. That he has won more races than anyone else is a tribute to his superb feeling for motor cars. He has been able to judge just how hard to push a car while still keeping enough in reserve to be able to finish the race. In other words, there is more to winning a race than just being able to go fastest around the track. But as motor racing becomes more competitive, even superlative drivers like Peter Brock need more than just the "seat of their pants" to keep them out in front. And this is where computers are being brought into the picture. Not that computers have not been involved in motor racing for a number of years. Most of the cars circulating around the track at Bathurst this year will have one or more on-board computers in their ' ' engine management systems''. These systems are used to control the ignition timing and fuel injection. The problem with existing engine management systems in cars is that they don't tell the driver anything about the state of the engine. They have been designed that way so that they are as unobtrusive as possible. But even if the engine management system did provide This diagram shows the main components of the Netcomm Racing Modem System. The system can cope with more than 60 sensors on the car. PC UHF RADIO 4 SILICON CHIP feedback to the driver, he would still want to know more, about the state of the tyres, brakes, suspension and so on. If racing drivers had this information about their cars' condition, they could push them a lot harder. In the meantime they have to err on the side of caution if they are to finish a race. Overcoming this lack of information has been a joint project between leading data communications manufacturer Netcomm Pty Ltd and Peter Brock's BMW racing team. Netcomm and Brock are in the process of developing a comprehensive monitoring scheme which will give real-time information about virtually every aspect of the car during a race. Called the Netcomm Racing Modem System (RMS) it was first featured in the car driven by Murray Carter in the 1987 Bathurst 1000. This year it will be featured in the Mobil BMW car driven by Brock as well as Murray Carter's Ford Sierra. Racing Modem System As the name suggests, the RMS is based on modems but there is far more to it than that. The basic rac- DATA .. CAR COMPUTER SENSOR 4FHE PIT CRE Peter Brock in the BMW M3 sedan at Oran Park on Sunday 28th August. Brock won this race. Will the Racing Modem System give him the edge to win at Bathurst in October? (Paul Buchtmann photo). ing modem system consists of a bank of sensors placed around the car, an on-board computer, a modem and a UHF (ultra high frequency) transceiver. The computer converts all the signals from the sensors into a digital data stream which is fed via the modem into the transceiver. The transmitted information is picked up at the pits by another transceiver and modem and fed into a computer where it is displayed on a video monitor for constant analysis by technicians. As the race progresses, technicians can monitor every aspect of the car and thereby are able to spot problems before they become disasters. Sensor functions Just to show how comprehensive the monitoring is, the various sensors and their functions are listed, as follows: • Engine tachometer: measures engine revolutions up to 9000 RPM. This is one of the screen displays used on the Apple Macintosh to display car sensor information. Note the thermometer displays for temperature readouts and the dial displays for speedometer and tachometer readings. (Paul Buchtmann photo). OCTOBER 1988 5 A laptop computer can be used to replay data recorded during a practice or race session using the Netcomm Racing Modem System. In this way, the driver can optimise his performance on the track. This photo shows how the Netcomm modem and UHF transceiver are installed under the dash of peter Brock's BMW sedan. The modem transmits at between 2400 and 9600 baud. (Paul Buchtmann photo). • Speedometer: measures up to 300km/h. • Backward/forward accelerometer: measures the acceleration and braking forces on the car and driver. • Up/down force: measures the downward force applied to the car by the spoilers. • Left/right accelerometer: measures the cornering forces on the car and driver. • Engine oil pressure. 6 SILICON CHIP • Engine oil temperature. • Fuel pressure: measures the pressure of the fuel delivered to the injection system. • Fuel temperature: measures temperature of the fuel to determine if vapourisation is occurring. • Water temperature: measures the temperature of the water as it passes from the engine to the radiator. • Detonation: an acoustic sensor monitors for the onset of this critical condition. If detonation occurs at racing speeds it can destroy the engine. • Exhaust gas: measures the carbon monoxide content of the exhaust gas. • Exhaust port temperature: each cylinder exhaust port is measured. This is another critical engine parameter. The piston heads are run at a temperature which is at times just below melting point. • Relative horsepower: a figure obtained from the existing engine management system on the BMW. • Battery voltage. • Battery current. • Fuel pumps: monitors which pump is operating. • Fuel flow: measures the rate of fuel consumption. • Gearbox oil pump. • Gearbox oil temperature. • Engine bay temperature. • Differential oil cooler pump. • Brake temperature: brake discs will glow red hot when braking at the end of the straights. If the calipers become too hot there is a risk that the brake fluid will boil. • Brake pedal pressure. • Brake pad wear. • Brake lockup: determines if the wheels lockup under braking. • Wheel spin: determines if the rear wheels lose traction under acceleration. • Throttle position. • Cabin temperature: air conditioning is not a feature of racing sedans. • Air temperature: measures the ambient temperature around the car. • Humidity: measures the ambient humidity around the car. • Air pressure: measures the atmospheric pressure. • Driver temperature: measures body temperature. • Driver heart rate. • Tyre temperature: the temperature of the tread casing of all four tyres is measured. If it exceeds a critical level, the tyre will disintegrate. • Tyre pressure. • Shock absorber temperature: each shock absorber is measured. If shock absorbers get too hot they cease to work properly and the car's handling suffers accordingly. This photo shows the prototype Netcomm system as used on Murray Carter's Nissan in 1987. • Vibration: measures vibration of the car body. That adds up to more than 45 sensors although we understand that some of these are not yet on the car. Tyre pressure monitoring is a particular problem; just how do you measure pressure in a spinning tyre? Netcomm weren't saying. Tyre temperature, on the other hand, is measured by infrared pyrometers spaced a critical distance away from each tyre. They have to get the spacing just right. Too far and sensitivity is degraded; too close and the oscillating wheel will rip out the sensor. Many of the sensor functions are already provided by the existing engine management system on the BMW and its anti-skid braking system (ABS). But that still left a great many others which have had to be installed. Processing the data Signals from the sensors are fed to a data acquisition computer which can accept up to 66 inputs. The computer is based on an 8-bit microprocessor with 32K of ROM (read only memory) and BK of RAM (random access memory). The computer prescales the inputs (ie, attenuates or amplifies the signal for optimum data transmission) and then performs analog-to-digital conversion. The digital data is encoded with a parity system for error correction - most important in a telemetry system of this complexity. The resulting 8-bit parallel data is then converted to a serial data stream to pass via an RS232 port to the Netcomm modem. The FSK (frequency shift keyed) signal from the modem is then fed to a transceiver (a combined transmitter and receiver) transmitting in the 470MHz band. The transmitted signal is picked by another transceiver in the pits area of the track and the detected signal fed to another modem to produce an RS232 signal fed to the port of a Apple Macintosh. This is specially programmed to display the information from the car sensors. Graphic displays Rather than just display the information as numerical quantities, the computer is programmed to display the information graphically. Hence, there are displays on the screen, to depict a speedo, tachometers, various thermometers to show the many temperatures be- ing monitored and so on. In this way it is easier for the technicians to monitor any changes just by glancing at the pointers, thermometer levels etc rather than having to pick specific figures off the screen. Not only is all the sensor information able to be displayed on the screen, it is stored in the computer for later more detailed analysis. Of course the Racing Modem System is heavily used in practice and training sessions. During these times the drivers can really push the car to the limits and beyond. This enables the technicians to build up comprehensive information about the onset of failure all the car's systems. It remains to be seen whether the Netcomm Racing Modem System gives Peter Brock and his team the necessary edge to win at Bathurst. But one thing is certain - it will be used on more racing cars in the future. •~ Our thanks to Netcomm Australia Pty Ltd and Communications Solutions Australia Pty Ltd for their assistance in the preparation of this article. OCTOBER 1988 7