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Electronic development could mean ecstasy for operators
Page 38
Page 39
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by Jerry Rodwell
MOST of today's commercials contain hundreds of yards of wiring, connected with hundreds of separate terminals — an electrician's nightmare! But developments now in progress could cut the wiring to only a few yards, with a dozen plugs and sockets.
One system being researched by Smiths Industries at its Witney, Oxford, factory virtually condenses the whole vehicle wiring system into three wires in a loop around the vehicle — the company calls it "Ecstasy".
By using electtonic coding systems, one of the three wires carries information from the dashboard to all the electrical items on the vehicle — lights, tachometer, speedometer, gauges, warning lights.
The other two wires are for power and earth.
With integrated circuitry — transistors, resistors, all the electronics bits "integrated" into a tiny chip of material — electrical items are made to sense when they should operate through a coding system.
Apart from obvious savings in wiring, this type of system provides valuable safety features. If any item does not function when ordered to, warning lights appear on the dashboard, or an audible warning system can be made to sound.
Head-up displays
Much publicity has been given to the so-called "headup" speedometer display. This is a basically mechanical system of displaying the speedometer reading at a point that appears to be floating in front of the vehicle bonnet.
Smiths have a demonstration vehicle fitted with a head-up display which we were able to try.
Although it takes a bit of getting used to, the image of the speedometer reading "floating" over the road ahead certainly makes it unnecessary to take one's eyes off the road to check vehicle speed.
Since it is entirely mechanical, with mirrors and light bulbs creating the display reflection on the windscreen, this system has dimming facilities so that display brightness can be reduced at night time.
There is also a boost facility to brighten it in strong sunlight, and adjustment for the position of the display to suit driver height.
The test vehicle showed some optical distortion in the windscreen, and apparently this is hard to get rid of.
But the overall effect is pleasing, and as an example of the possibilities of this kind of display it is most convincing.
But since it depends on a slanted windscreen for its optical effect, and is also rather bulky, it cannot be applied to commercials in its present form due to their vertical screens.
In fact, according to Smiths' chief of electronics, Mr Brian Shepherd, it is unlikely to go into production in its present form. More sophisticated and desirable systems are already being developed.
Some of these new systems are capable of presenting the driver with a whole dashboard of information on speed, engine revs, fuel contents, oil pressure, water temperatures — in fact everything he wants to know through entirely electronic means with hardly a mechanical moving part aqwhere.
Over some years, various systems aimed at this have been tried, and rejected.
A half-way solution from Smiths has been their electronic speedometer — much the same as their already well-known electronic tachometers. But though this is perfectly usable and reliable, it still depends upon mechanical means to rotate the indicating needle, and provide an odometer read-out.
Exotic effects
Now exotic effects using chemicals that react to electricity are being tried. Among them are liquid crystals and dc electroluminescent devices.
Liquid crystals consist of a chemical, sandwiched between thin glass plates, which, when an electric current is applied turns from a transparent to a "milky" state. Mr Shepherd demonstrated a display which included speedometer — reading directly in digits — and a fuel gauge, and another with a sectional speedometer and gauges, each using a single plate of liquid crystals.
These crystals operate on voltages compatible with those used by integrated circuits, and in almost every way are ideal for commercial use.
They can provide a display which is easy to read, and can be made to adjust in brightness automatically to compensate for light levels outside the vehicle — such as when driving into a tunnel from bright sunlight.
But in their present state of development they have a major drawback: their life is limited.
Though it is hard to say what their life would be in commercial use, it might at present be only a few hundred hours. Mr Shepherd reckons that until a life of many thousands of hours can be guaranteed, the present high cost of liquid crystal displays will prevent their use in vehicles.
Another impressive display is provided by phosphors reacting in a manner known as de electroluminescence.
Again, a complete dash panel layout had been made by Smiths, with all the gauges needed, laid out under a filter panel.
In this case, sections of the display are made luminous when electronically "called up" to form a display representing, for instance, the speedometer. As the road speed increases, segments of the speedometer dial light up.
This display approaches the planned ideal closely, in that the whole panel only shows information when it is needed.
For instance, fuel contents would be shown normally only when the tank was getting low, so that the driver is not distracted by the gauge until he needs the information. He is able to "call up" the fuel gauge when it is not being displayed, however, by just pressing a button.
Equally, warnings of low oil pressure, high engine temperature, battery condition, would not be displayed until there was something to warrant the driver's attention. By this means, a peaceful, blank panel is presented until faults are approaching.
As with so many things, there is a problem here. The dc thermoluminescent displays depend on a voltage higher than that used by integrated circuits, and so are not easily combined into integrated circuits or commercial vehicle power systems.
Maintenance
Maintenance for these electronic systems should consist for the garage man — of a plug-in replacement part where there was a failure; rather like servicing a colour television. There should be no need for specialized electronic knowledge with such a system, since by its nature diagnosis of a fault could be made by just plugging a test machine into the circuit, Such a machine would automatically scan the system, and read out any faults, and their exact location.
Although all this may seem "space-age" and far from reality, it is probable that we shall see such systems in only a few years in wide use on commercials. And simple diagnosis and maintenance means less work for the garage, and less VOR time, which adds up to more money for operator.