Alt-BEAM Archive
Message #03018
To: "'Dennison'" dennlill@buffnet.net,
From: Wilf Rigter Wilf.Rigter@powertech.bc.ca
Date: Wed, 5 May 1999 20:55:30 -0700
Subject: [alt-beam] Re: Bicore head targeting?
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As discussed at the chat today here is a (new?) idea.
With a phototropic BiCore head mounted on a uCore walker, the head should b=
e
free to turn towards a light target and send an error signal to influence
the walker uCore to start turning toward the target. From some
experimenting, I found that integrating both BiCore phase signals produces
two average Vdc error signals proportional to each phase duty cycle. Since
the duty cycle of each phase is complementary to the other phase, this
produces two complementary error signals which can be applied to the two
corresponding uCore bias points to lengthen the process in one Nv and
shorten it in the other Nv, in effect causing the walker to turn. (ie <
50% =3D turn left, 50%=3D straight ahead, >50%=3Dturn right) Given a relati=
vely
high oscillation frequency for the Head BiCore, it is simply a matter of
connecting both BiCore outputs through 2 suitable resistors to the uCore
bias points using the uCore caps themselves to integrate the average DC
component of the BiCore outputs. =
The problem is that the head circuit stops sending out an error signal (50=
%
duty cycle) when fully turned and locked on the light source. So once the
head is turned into position: no more error signal and no more influence. =
Solution ? add a centering spring(s) between the head and the walker,
tensioning the head to face to the front of the walker. Now when the head
turns, the BiCore has to "work" to keep it turned towards the light and
therefore keeps sending an error signal to the uCore until the head and
walker both face straight towards the light. 8^)
What do you think?
<> =
=09=09Wilf Rigter=09mailto:wilf.rigter@powertech.bc.ca
=09=09=09=09=09tel:=09(604)590-7493 =
=09=09=09=09=09fax:=09(604)590-3411
> -----Original Message-----
> From:=09Dennison [SMTP:dennlill@buffnet.net]
> Sent:=09Tuesday, April 27, 1999 12:01 PM
> To:=09John A. deVries II; Sean Rigter; Wilf Rigter; van Zoelen, Bram
> SSI-TSEA-352; Chiu-Yuan Fang; Dave Hrynkiw; Beam List (E-mail)
> Subject:=09Bicore head targeting?
> =
> I found out from dave that the controll system for his and Mark T's Heads
> are not Bicores. They use some other "poppernets" or something like that
> to control things. So that brings me back to bicores, how does one tell i=
f
> the bicore has 'targeted' something? You should be able to compare pulse
> durrations, when the pulse durrations are equal in length you know that
> the head has 'locked on' and is no longer in motion. But how to compare
> these pulse's is the question. My first Idea was to connect both outputs
> in some fashion to the +v or gnd side of a sizable cap. The idea goes
> that, while one output charges the cap, the other output discarges. When
> the pulse durations are equal, then in theory the average net change in
> voltage across the cap should be zero. That would mean that at any other
> point, when the avereage net change was a positive value, the head was
> still in motion. I know it's confusing, but think about what would happen
> if the cap was being charged and discharged.
> =A0
> Dennison
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