Thank you for all your suggestions.

About the energy requirments... we do have one. 200 joules for a 21
meter race (its a small robot) and an allowed "production budget" of
CAN 100 (the robot, if mass produced, cannot cost more then $100 to
build).

I was thinking of having the robot o forward (with no control for
that), and using the beacon to correct my course.

The prefered solution is to build the bugger so well that it just
travells straight for the 21 meters... but alas, another requirmet is
that some sort of guidance system must be included (usually this
project involves obstacles the control system must avoid, the professor
took those out since the race is outside).

Cheers,

G_dir


wrote:
On Sat, 23 Sep 2006 01:12:12 -0700, Richard Clark
wrote:

On Sat, 23 Sep 2006 03:07:50 GMT, wrote:

VOR is very different.

Hi Alison,

Yes, I already admitted the term was probably pulled from an alphabet
soup of navigational equipment I've calibrated: TACAN, VOR, DME, ADF,
LORAN (although more commonly marine application) and on and on. The
mechanical phasing systems were a workable kludge. But what kludges
nonetheless. I've even navigated by the time differential between the
Naval Observatory encoded signal in LORAN stations and my atomic clock
aboard a sub tender (our LORAN was broke).

I flew the las AN and also all the other Alphasoup but as a civi pilot
and small boater. Even used LF ranges and DF off of broadcase
stations. There are a lot of electronic ways to navigate.

Which is eminently suited to the problem.

AN has 180degree ambiguity

Which is not an issue for the stated problem.

True, only noted it.

A light path can be resolved with hardware logic instead of software.
Faster performance.

Optical interferometry.

Hardly. This is gilding the Lily and painting the Rose. The optical
analog of the AN system is sufficient to the problem. Simpler beacon
methods would prevail even here.

I never said the hard way was best!

Me, I'd go with a beacon at UHF for small antennas and ease of
construction. Since the car has some control system I can resolve
where the front should point from there. A two antenna TODA can
provide enough phase info to generate an error signal. The real work
is the servo loop.

Of course a simple optical bangbang system using the same tricks
as heatseekers would work.


The difficult issue is one of a closed feedback loop and maintaining
stability, not deciding if one is on or off the path. That is dirt
simple. What you DO with the information is the logical nightmare,
because errors compound quickly and information descends into
statistical nonsense in its out of phase application.

Clasic servo problem. Classic answer, KISS!

In a recent robotic car rally, the big name universities and
corporations with million dollar budgets, gizmos galore (multiple GPS,
radar, and what have you) and plenty of engineering talent were
literally blown off the road by an insurance broker who hobby funded a
garage crew outfit.

Been there and done that in other areas. Nothing beats a few good
minds and a well stocked junkbox.


Allison