Alt-BEAM Archive
Message #07404
To: alt-beam@egroups.com
From: emolson@capecod.net
Date: Fri, 5 Nov 1999 06:27:33 +0000
Subject: [alt-beam] Re: CONTEST
> Reply-to: alt-beam@egroups.com
> Date: Sat, 06 Nov 1999 18:13:12 -0400
> From: michael.hirtle@ns.sympatico.ca (Michael Hirtle)
> To: alt-beam@egroups.com
> Cc: beam@sgiblab.sgi.com
> Subject: [alt-beam] Re: CONTEST
That wouldn't really keep people from cheating, they could
just glue together some caps and a cell and drag it through the
salt..
btw, when would the deadline for the contes bet? I would like to take
part, but I've just started making BEAM bots and it will probably
take me some time to get a photovore working.
Eben Olson
> I think their should be an actual picture of the salt trail with the bot not
> just a discription becaus epeople can lie, and the bot could just be a bunch
> of parts put together and not actualy work.
>
> Evan Dudzik wrote:
>
> > i think that for the purpose of this contest, the bots
> > need not be expensive... i may even make available for
> > sale for a reasonable price some of my own parts
> > (mostly just about 20 pager motors along with a few
> > odd solar cells...) the entry will be simple, and
> > should be really easy with access to a scanner or a
> > digital camera... just a top and bottom view of the
> > bot next to a ruler will be OK, more is recommended...
> > and a salt trail over a period of 5, 10, 20, or 30
> > minutes, depending upon how active your bot is... just
> > scatter salt evenly on a piece of black paper, and let
> > the bot loose with a lamp at one corner of the paper
> > (please specify where the lamp is...) and when your
> > bot has made some good tracks, either photograph the
> > paper with the salt trails, or provide a detailed
> > drawing of the trails (for those with no camera).
> > descriptions of your bots should be included...
> > thanks, I should have a page up and running soon...
> > Hopefully I can get some entrants! (2 possible
> > entrants so far... thanx!!!)
> >
> > --- Michael Hirtle
> > wrote:
> > > If i can scrounge up enough money i think i will
> > > participate.
> > >
> > > Evan Dudzik wrote:
> > >
> > > > would anyone be interested in participating in a
> > > > contest (like chiu's) that was NOT hosted by a
> > > "BEAM
> > > > god?" (ie- ME) i know that when a major BEAMer
> > > like
> > > > chiu has a contest, it commands respect, thats
> > > just
> > > > the way it is: but it seems that whenever i ask a
> > > > question on my page, or ask people to participate
> > > in
> > > > something, only like one or two nice people
> > > actually
> > > > respond.. and thats really pale in comparison to
> > > the
> > > > hours people spend making bots for chiu's
> > > contests...
> > > > i just want to see for the last time if BEAM
> > > really is
> > > > just led by a couple masters, or if the lower
> > > levels
> > > > of BEAMers can have fun too... so would anyone
> > > like to
> > > > participate in a contest i would start? the theme
> > > > would probably be just a most interesting behavior
> > > > photovore... standard rules. as for prizes?
> > > well, if
> > > > nobody donates anything, they will be really small
> > > (se
> > > > parts packs??? i dunno...) because not everyone
> > > can
> > > > afford huge amounts of parts like escaps and other
> > > > expensive motors and things, let alone give them
> > > away
> > > > as prizes... sorry to offend all you higher ups,
> > > but i
> > > > am trying to speak for the less super BEAMers.
> > > >
> > > > =====
> > > > +------------------------+
> > > > |http://surf.to/photovore|
> > > > |Photovores online! |
> > > > |Evandude Dudzik |
> > > > +------------------------+
> > > > __________________________________________________
> > > > Do You Yahoo!?
> > > > Bid and sell for free at http://auctions.yahoo.com
> > > >
> > > >
> > >
> > ------------------------------------------------------------------------
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> > > http://www.egroups.com/group/alt-beam/?m=1
> > > > -- Free email groups at eGroups.com
> > >
> > >
> > >
> > >
> >
> > =====
> > +------------------------+
> > |http://surf.to/photovore|
> > |Photovores online! |
> > |Evandude Dudzik |
> > +------------------------+
> > __________________________________________________
> > Do You Yahoo!?
> > Bid and sell for free at http://auctions.yahoo.com
> >
> > ------------------------------------------------------------------------
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> > http://www.egroups.com
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main(){char x,y=-1,t,n,*c="-=+X# \nrf.mpsbo.toylph@ld";while(++y<25)
{for(x=0;x<80;){float a,b,d,i=2.2/25*y-1.1,r=2.8/80*x++-2.1;t=b=d=0;do{
a=b*b-d*d+r;d=2*b*d+i;b=a;}while(++t<32&&b*b+d*d<4);for(n=0;t&~1;t/=2,
n++);putchar(c[x>79?6:y>23&&x<19?25-x:n]);}}}
7405 Fri, 05 Nov 1993 18:24:03 -0600 [alt-beam] Re: PS HEAD V2 beam@sgiblab.sgi.com SG Brad:
I asked Wilf about the V2 and the V3. he replied with this:
Hi Sparky,
V2 and V3 are on the backburner for now: too tricky to adjust! But V1 is
stable and works fine. Check out Darrell Johnson's site for construction
details
right, now i can get two fleds with polarity switched to light up at the
motor outputs. but attached a pager motor and nothing happens! then the
power is very very quickly drained.
gonna switch the HC for an AT tonight and see if there is any results.
Somethng is draining the juice!
-Sparky
At 12:04 PM 11/5/99 -0600, you wrote:
>for every one on the ps head project,
>i was digging and found this in the archives
>it doesn't have the circuitry for the fled,
>but it has a very indepht description of the operation of the circuit.
>it helped me understand the operation of the circuit alot better
>later
>brad
>
>Wilf Rigter wrote:
>>
>> Prodded by Justin, here is an updated and tested version of the
Power_Smart
>> head circuit complete with a description of operation.
>>
>> The Power_Smart Head V2 - 9/99 - wilf rigter
>>
>> NOT A BICORE
>>
>> The basic BEAM head is a tried and proven design with a substantial number
>> of working units posted at various websites. However the conventional
bicore
>> head circuit is difficult to adjust to operate over a wide range of light
>> conditions and is notorious for high power consumption. The switching
losses
>> are significant, because the bicore is continually reversing the motor
>> current. In fact, current required for a motor in a bicore head is almost
>> double that needed with the motor connected straight to the power supply.
>> Moreover the circuit consumes power even when the head is locked on and not
>> moving.
>>
>> HIGH/LOW/OSCILLATE
>>
>> The Power_Smart (PS) head , as the name implies, was designed to address
>> these problems while maintaining the same simple "freeformable" circuit
>> layout and similar components. The PS circuit uses what could be called a
>> modified bicore oscillator but which I will call the High/Low/Oscillator
>> (HLO). This is in fact a textbook CMOS oscillator with a voltage
>> controlled Pulse Width Modulation input. This PWM control input is simply a
>> 1M resistor connected on one side to a voltage source (in this case the
>> midpoint of two photo sensors ) and connected on the other side to bias
>> point of the oscillator timing components (U1-pin2). Two photo sensors use
>> reasonably well matched photodiodes or light depended resistors to form a
>> voltage divider (or half bridge), with the voltage at the midpoint close to
>> 1/2 Vcc when the light on each sensor is balanced. This 1/2 Vcc voltage is
>> near the input switching threshold of standard 74HC240 (not HCT) logic. The
>> control range was designed so that when the photo sensors are balanced,
>> the oscillator produces a square wave with 50% duty cycle. When unbalanced,
>> the duty cycle changes between 0% or 100% (full reverse to full forward).
>> The two complementary outputs of the HLO are connected to the inputs of a
>> bipolar pulse generator.
>>
>> A CHANGE OF PHASE
>>
>> The HLO is followed by the Nv/Nu (2N1) bipolar pulse generator. The 2N1
uses
>> two capacitors and one resistor. The produces positive going AND negative
>> going pulses with a pulsewidth about half the period of the HLO output. For
>> the duration of the pulse width the output of the 2N1 is in phase with the
>> resistor signal. If that signal is longer than the pulse width, the 2N1
>> output changes to the inverse of the resistor signal. Since the resistor
>> input signal and the 2N1 output are connected through a driver stage to the
>> motor, it is the difference (out of phase) between these two signals which
>> cause the motor current and rotation. Therefore a steady state signal
>> applied to the 2N1 resistor input, when the sensor bridge is greatly
>> unbalanced, will cause continuous rotation. When the sensor bridge is
>> balanced and HLO oscillator produces a 50% duty cycle (squarewave), there
>> is no difference signal developed between the 2N1 input and output and the
>> motor does not rotate. When a HLO output is a pulse width modulated
>> oscillation, the 2N1 circuit produces a pulse train phaseshifted with
>> respect to the input signal with a pulse width difference which is
>> proportional to the sensor bridge imbalance. This difference signal is a
PWM
>> signal the causes slow rotation of the motor when the sensor bridge is
>> slightly unbalanced.
>>
>> TWO NEURONS IN ONE
>>
>> The Nv/Nu (2N1) circuit in one sense combines the functions of both types
>> of neurons. Normally a Nu integrates a signal applied to the resistor with
>> the capacitor grounded. A Nv differentiates a signal applied to the
>> capacitor with the resistor grounded. The Nv/Nu stage applies signals to
>> both the capacitor and the resistor. A second capacitor and second inverter
>> is used to provide positive feedback to overcome the common problem of
>> linear inverter high frequency oscillation as a Nu input voltage passes
>> through the linear region. The driving outputs also act as virtual grounds
>> for the respective capacitor and resistor. (note that the earlier power
>> smart head used just one 240 stage for the Nv/Nu neuron resulting in bursts
>> of high frequency oscillations especially when using the preferred 74AC
>> logic) .
>>
>> HUNTING/SEEKING/TRACKING
>>
>> When there is a strong light source off-center from the photo sensor's line
>> of sight, the midpoint of the sensor bridge is strongly unbalanced. This
>> causes the PWM control input to saturate (full forward or reverse) and the
>> oscillator output no longer pulses but stays high or low depending if the
>> control voltage is higher or lower than the linear region. In this
saturated
>> state, the motor is driven continuously left or right, turning the photo
>> sensors towards the light source . This provides a feedback servo loop
>> driving the motor to balance the light level on the sensors until the
>> control voltage is restored to 1/2Vcc. While the oscillator is saturated,
>> all power is continuously (efficiently) applied to the motor without the
>> switching losses common in Bicore designs.
>>
>> BUFFERIN/BUFFEROUT
>>
>> The output of the HLO and the Nv/Nu stages are buffered with 2 parallel
>> inverters each and these can directly drive a small gear motor of the BG
>> Micro type. If more power is needed then I recommend using a complementary
>> mosfet h-bridge to source and sink up to 1A with low losses. With a heavy
>> duty motor and the more powerful mosfet h-bridge, a PS head can be used to
>> position a camera or other device (ie an electromagnetic BB gun : you'll
>> shoot your eye out!).
>>
>> ONE MORE TIME
>>
>> To recap, the HLO generates a High or a Low output when the photo sensor
>> bridge is unbalanced and Oscillates when each photo sensor receives roughly
>> the same light. The complimentary outputs of the HLO connect to the inputs
>> of a Nv/Nu stage which generates pulses when the HLO oscillates. The motor
>> driver consists of a buffered bridge connected to one HLO output and the
>> Nv/Nu output. The bridge drives the motor in one direction or the other
when
>> the photo sensors are unbalanced. When the photo sensors are slightly
>> unbalanced, the motor driver produces narrow pulses (reduced power) to
nudge
>> the head position towards the balanced condition. When both photo sensors
>> are equally illuminated, the HLO oscillates width 50% dutycycle square
wave
>> output. At this frequency and duty cycle, the Nv/Nu stage generates pulses
>> which are precisely in phase with the HLO output. Therefore the bridge
>> outputs are the same polarity, the motor is stopped and the brake is on.
>> This is a low power standby mode which requires just 1 ma of supply
current.
>>
>> 240 or not 240
>>
>> Since only 6 inverters are needed for the PS head, it is also possible to
>> make a PS head using only one 74HC04 chip and MOSFET h-bridge or for small
>> motors, use just a single 74AC04 chip. For a 2DOF PS head just duplicate
the
>> circuit and add another motor.
>>
>> AN EYE FOR AN EYE
>>
>> I recommend installing red and green LEDs connected in reverse parallel
>> across the motor to indicate direction of motor rotation providing visual
>> feedback.
>>
>> X MARKS THE SPOT
>>
>> Although not shown in the schematic, an auxiliary IR LED can be mounted on
>> the head to provide an active IR SPOTLIGHT. The LED current can be also be
>> synchronously Pulse Width Modulated to increase IR brightness while
>> reducing overall power consumption. When using the IR SPOT, make sure the
>> head is far from reflective walls, etc since the head will lock on any
>> nearby object reflecting the IR beam.
>>
>> That's it for now: but remember feedback is always welcome here.
>>
>> enjoy
>>
>> wilf
>>
>> <>
>>
>> Wilf Rigter mailto:wilf.rigter@powertech.bc.ca
>> tel: (604)590-7493
>> fax: (604)590-3411
>>
>> ------------------------------------------------------------------------
>> Name: SM_HEAD2.gif
>> SM_HEAD2.gif Type: GIF Image (image/gif)
>> Encoding: base64
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