2000-11-28 – I got slack in my updating

Tut tut, I got slack in my updating. This is because I am trying to
rewrite the site to better improve the navigation, and introduce PHP
functionality, whilst doing everything else in my life! There are several new
interesting bites, and here are two new ideas/musings.

For an automatic windscreen wiper system you need a sensor
that detects the visibility available through a part of the screen covered by
the wiper. One method might be to have a system of IR transmitters and receivers
and measure the reflectance back to the sensor. It obviously isn’t possible to
have any of the parts on the outside of the car windscreen. Another system might
be to have a small staring array which allows you to measure the sharpness of
the images it sees. The problem with this is that in a fog or mist, the wipers
would start, and so would squeak annoyingly. Of course, no matter how smart your
system is, it should still have a manual over-ride to prevent problems which
cannot be solved. Try to think of how your eye and brain determines when the
screen needs a wipe, and don’t forget you still need to be able to squirt some
washer fluid on there if it is mud, and not water. The processing load for the
imaging system would be quite high, but the work could be done by the same PC
you have installed to play your MP3’s off. An old P200 would do a stirling job,
I suspect, loaded with a copy of Linux and a music processor. A nice serial port
connection would be fine for the controls of the player and the inputs for the
wiper could be parallel port, or even a USB camera, depending on the exact
system you opted for. Remember that the MP3 will need most of your processor
power, and you don’t want the wipers to interfere with your listening pleasure.
You can probably get a 12volt supply from somewhere to prevent the need for an
inverter, but don’t forget the car battery has lots of electrical noise, and the
actual voltage goes up as high as 14.4 volts due to the charging. You will also
need a +5 volt supply, and a -5 and even a -12, depending on exactly what
hardware you hang of your system, though scanners will be a luxury. A removable
hard-disk would be very handy, however. The keyboard and a glidepad might be
useful for doing work on, but where are you going to put a screen? Don’t forget,
it is illegal in the UK to have a screen where it may cause a distraction to the

¬†On a related note…

Why don’t cars have mains inverters built in? I have a
separate box, which plugs into the cigarette lighter, which then steps up the 12
volts to 240 volts. Obviously this can only be used for a relatively low powered
device, such as a laptop, but with a current trip limited to 1A a built in
system would be a big selling point. Let’s face it, everyone has given up
smoking, yet everyone I know still has one or more things in the cigarette
lighter socket. Phone chargers are the most common, but spotlights, small
torches, Radar detectors, even car alarms, all run from that single 12 volt
supply. A modern car should have an inverter, as well as a pair of cigarette
lighter sockets!

As you may be able to guess, I have been doing a lot of travelling this
last few weeks. Fuel costs are killing me!

Leave a Comment