HELP!!! PIC-less Simple Obstacle Avoiding Mobot

[blackberry04]

Mga sir, posible kaya ito?

I have all the components needed (IR LED, phototransistors, photodiodes, LDRs, etc.)
Saw this IS471 on a site..pero ngtnong na ko sa mga shops pero wla yatang available dito..pero kung meron sna nu'n I will be able to do this 
on my own..
Ang gusto ko sanang function ng mobot is, pag nakadetect siya ng obstacle, say on the S2 side, hihina ung current flowing through the Motor 1(M1) or make it 0v para, greater ung speed nung Motor 2 at para makapivot siya to the left..same as the other sensor. So ang paglalabanan lang ng dalawang motor is their currents, to dictate its direction.
Hindi pa po kasi kami natuturuang magprogram ng PIC eh..and my prof said its must be simple as it is.

Thnx in advance, for those who have time to help

[zer0w1ng]

How would you detect obstacles?

Light sensors don't detect obstacles unless the sensor is already covered.
And it will be too late to turn the mobot at this time.

Ultrasonic is better.
It could detect obstacles even few feet away.
But using ultrasonic is a bit hard to use without MCU.  

[marcelino]

IR pwede din....

but we must push the limit of IRED then mataas na amplification sa receiver.

[tiktak]

TSOP2238 from vishay kelangan lang yung IR LED ay modulated ng 38khz pede na 555 para dun

[blackberry04]

@sir mamart: wlang PIC  

@sir zer0w1ng: proximity sensor sir, on other site, they have this IR pair; an IR LED comes side-by-side with a photoresitor

this, taken from : http://g9toengineering.com/AllSaints/infraredproximity.htm
"An IR proximity sensor works by applying a voltage to a pair of IR light emitting diodes (LED’s) which in turn, emit infrared light.  This light propagates through the air and once it hits an object it is reflected back towards the sensor.  If the object is close, the reflected light will be stronger than if the object is further away.  The sensing unit (for this experiment a Sharp IS471FE will be used), in the form of an integrated circuit (IC), detects the reflected infrared light, and if its intensity is strong enough, the circuit becomes active.  When the sensing unit becomes active, it sends a corresponding signal to the output terminal which can then be used to activate any number of devices.  For the purpose of this exercise, a small green LED will turn on when the sensor becomes active"

I dont have that Sharp IS471 , I only got phototransistors, photodiodes, and LDRs and sabi ng prof namin light sensors lang daw ang gamtin

How about this: http://home.cogeco.ca/~rpaisley4/PhotoDetectors.html
Yung -Section 1- : Visible Light Photo-Detector Circuits , sakto na po ba yan...palitan ko lng ung LED ng DC motor?

Thnx

[tiktak]

pede yung TSOP2238 pamalit dyan sa sharp available ito sa e-gizmo, IR Receiver + amplifier na yun

[blackberry04]

w8, pwede rin bang gamitin ang IR LED as receiver?

[zer0w1ng]

One problem with optical sensing, like IR, is that it is very dependent on the reflective surface and the surface angle of the obstacle.

If the obstacle is has a flat and shiny surface and is facing the sensor, a HIGH value will be read.
And if the angle is tilted/changed, the value will be lower or sometimes no IR light will be detected at all.
This IMHO is difficult to determine the "nearness" of the object and the ability of the mobot to turn BEFORE hitting the obstacle.

With ultrasonic sensing, the delay of the return ping is measured and multiplied with the speed of sound, you will get the distance.

IR is OK with line followers for the distance and angle of the floor is constant.

[aidzmana]

kelangan ko po din ng walang PIC na mobot para sa project nmin.. need schematic.. ang gamit lng po ay logic circuit/relay at proximity sensor..

[rdpzycho]

'yung unang mobot na ginawa namin parang ganito, logic gates lang, pero hindi obstacle avoiding, kapag nabangga siya saka lang talaga iiwas.

[nucleus]

posible ito with a lot of comparator

[blackberry04]

@sir zer0w1ng:  endorser ng ultrasonic sensing ah , kung pwede nga lang sir di na ko mgppkahirap. Mejo mahal at un eh
_______________

i cant get my IR pair working eh...ayaw magreflect
question lang, pwede ba ko magsub ng comparator sa isang Op-amp


Thnx

[aidzmana]

'yung unang mobot na ginawa namin parang ganito, logic gates lang, pero hindi obstacle avoiding, kapag nabangga siya saka lang talaga iiwas.

gnun po ba.. hayss. ewan ko ba dun sa prof nmin kung pde lng mag pic eh. haiz

[rdpzycho]

pwede naman, switch lang kasi sensor namin noon kaya kapag nabangga saka iiwas. kung proximity 'yung sensor, pwedeng avoidance.

[aidzmana]

la ko mahanap na schematic.. yohohohoho..

[blackberry04]

@aidzmana: LOL aidz not2 toh, amp dami jan...mukhang mdli sa schem pero sa actual di ko mapagana

@rdpzycho : haha...kung ganun lang proj namin..gagawa kami ng sandamukal...meron kcng step by step nun sa Instructables.com

[rdpzycho]

^ ang papalitan niyo lang naman doon e 'yung sensing part.

[aidzmana]

haha. cge salamat idol.. we'll try our best.. blackberry isa kang malaking BETL*G

[aidzmana]

ser meron ka pa pu ba nung schematic ng mobot niu? ung pag nabangga chaka iiwas..

[rdpzycho]

wala na (actually, nung ginawa namin 'yun, naka-sulat lang sa board 'yung schematic ). matagal na 'yun. comparator lang 'yun at monostable multivibrator (fixed 'yung time na iikot 'yung mobot). forward-reverse lang 'yung motor. then merong ilang gates para lang ma-sigurado na hindi sabay mag-on 'yung magkabilang side ng H-bridge.