Where is the cars URL?
As geeks worldwide continue to come up with inventive ways to deploy the hit Brit minikit Raspberry Pi, and the publication of a 101 uses for a...* guide is surely just a matter of time, Reg reader Ray Brooks has been in touch to show off his prototype carbot powered by the diminutive ARM-compatible computer. Ray is a …
Anyone doing anything in the electrical engineering block at Birmingham Uni should have an advantage here: the 2nd year project is to build a line following robot, which are then raced. Ours was based on a PIC16F84, which should tell you something about how long ago I was at uni. Clever people did stuff with camera's and visual processing (which didn't work for most of them, and sure as hell wasn't run on a PIC16F84) efficient engineering types used arrays of light sensors.
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> I built a line follower so long ago it used a couple of VDRs and discrete analog components
Yep. I built one like that in 'O' level Physics.
Getting the illumination level right turned out to be important, so I built an ALC out of the three outputs. And then a voltage comparator on that output to detect the front end going over a step :-)
"based on a PIC16F84, which should tell you something about how long ago I was at uni"
Last week? When I was at Glasgow Uni we used discrete logic chips for that kind of thing. Or an interface to a PC where we'd write the code in Turbo Pascal. None of these fancy newfangled PIC things. ;)
White-line following cars? How very 70s! ;)
I remember seeing a circuit for a white-line following model car in an ETI magazine back in 1979 or thereabouts. Only that one didn't use complex computer chips or software; as I recall, it simply consisted of two side-by-side phototransistors either side of a light bulb, feeding into an op-amp-based voltage comparator, which in turn fed current to the steering servo, according to which one of the phototransistors was receiving more light from drifting over the white line than the other. No CPUs or software involved, just a basic electronic feedback loop consisting of a handful of resistors, capacitors, transistors and a cheap op-amp IC (an LM 3900 IIRC.)
These days the solution wold consist of a billion-transistor CPU, a gig of RAM, a CCD camera and ten thousand lines of optical-recognition code to achieve the same result!
(Reg, we seriously need a "Get off o' my lawn" icon for us old farts that remember this shit...)
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