Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: intwizs on June 27, 2009, 09:47:40 PM

Title: *URGENT* noob question....fr competition...
Post by: intwizs on June 27, 2009, 09:47:40 PM
i started making the 40$ line follower...
i need to make a bot which follows white lines and also avoid obstacles....
but the circuit is such that either it can follow white lines
(OR)
it can follow black lines+avoid obstacles....

and also, i couldn't get CdS photoresistors......can i use phototransistors as well? with the same circuit?

Title: Re: *URGENT* noob question....fr competition...
Post by: intwizs on June 27, 2009, 10:47:49 PM
hw cme ppl are jst viewing the post nd not answering...hello anyone ther?
Title: Re: *URGENT* noob question....fr competition...
Post by: SmAsH on June 27, 2009, 10:53:51 PM
it has only been viewed 16 times! be patient! and for the love of god, use spell checker!

you can use phototransistor but you will have to change a few things...
you could use a sharp ir sensor for the obstacle detection possibly on a servo.
what do you want it to do if it runs into an obstacle?
Title: Re: *URGENT* noob question....fr competition...
Post by: intwizs on June 27, 2009, 11:02:35 PM
i want it to avoid the obstacle and keep moving on the line.....
i cant afford servos...they r way too costly here.....i already have parts from my previous bot.....

im making another line following robot by following the other tutorial as well....
but it needs a servo, what can i do to a DC motor to make it run autonomously?--s in under a programmed microcontroller....
Title: Re: *URGENT* noob question....fr competition...
Post by: SmAsH on June 27, 2009, 11:03:58 PM
okay, im confused...
what parts do you have from your old bot? and what is your budget for this robot?
Title: Re: *URGENT* noob question....fr competition...
Post by: intwizs on June 27, 2009, 11:12:38 PM
budget huh? well, within 3k
one servo costs 1.2k here, dc motors are cheaper

i have 4 DC motors, they're of low rpm so they're best suited for line following right?
a chassis, wheels, an RC, and a circuit (i forgot what IC its based on--cuz a partner has it)
Title: Re: *URGENT* noob question....fr competition...
Post by: SmAsH on June 27, 2009, 11:13:35 PM
okay... what currency we talking here?
Title: Re: *URGENT* noob question....fr competition...
Post by: intwizs on June 27, 2009, 11:16:43 PM
ruppees...lol..why is that relevant?
I'm willing to put in the work, I gotta win a couple of competitions
Title: Re: *URGENT* noob question....fr competition...
Post by: intwizs on June 27, 2009, 11:37:34 PM
hello?
any actual help?pls
Title: Re: *URGENT* noob question....fr competition...
Post by: Metal Slug 2 on June 28, 2009, 12:51:12 AM
i want it to avoid the obstacle and keep moving on the line.....
i cant afford servos...they r way too costly here.....i already have parts from my previous bot.....

im making another line following robot by following the other tutorial as well....
but it needs a servo, what can i do to a DC motor to make it run autonomously?--s in under a programmed microcontroller....

Try buying a servo from ebay with free shipping.  To control a DC motor you need either two h-bridges (per motor) or a motor driver.  As for a microcontroller to get the job done, are you building the $50 robot?.  if you are, good, it will work for your robot.  If you arent, you can buy a nearly complete kit (no servos or battery) for it here: http://www.circuitgizmos.com/products/cgsorkit1/cgsorkit1.shtml (http://www.circuitgizmos.com/products/cgsorkit1/cgsorkit1.shtml)  .  But then you will also need a programmer, look on the $50 robot tutorial. 

btw, knowing your currency is very relevant.  Most members of SoR relate to any product in USD.  Therefore if you state you have a 3k budget, we may just assume you have 3k USD, and not 3k rupees.  You can see what problems that may cause...
Title: Re: *URGENT* noob question....fr competition...
Post by: intwizs on June 28, 2009, 01:05:11 AM
alrite so with a motordriver+Dcs, means i dont need a servo rite?

motordriver is the one wid L293D IC? I mean, ive made a circuit based on it i.e the one in the 40$ line following robot tutorial......

Title: Re: *URGENT* noob question....fr competition...
Post by: sonictj on June 28, 2009, 01:22:21 AM
Quote
alrite so with a motordriver+Dcs, means i dont need a servo rite?

motordriver is the one wid L293D IC? I mean, ive made a circuit based on it i.e the one in the 40$ line following robot tutorial......

A motor driver (H-bridge) is what is required to generate enough current to drive a motor.  A servo has this internally.  You need to know how much current your motors pull.  An l293d is a .6 amp motor driver intended for small dc motors.  if your motors draw too much current you will blow the l293ds.

I don't understand why you need servos.  Servo's are just gear motors with a convenient interface.

oh and looking at a few of your posts here I think you should take a look at this
http://www.societyofrobots.com/robotforum/index.php?topic=1480.0 (http://www.societyofrobots.com/robotforum/index.php?topic=1480.0)
Title: Re: *URGENT* noob question....fr competition...
Post by: intwizs on June 28, 2009, 01:45:00 AM
listen...im making two robots...
one that has a microcontroller.....
that one requires servos right? do DC motors have the capability to directly run under microcontrollers?
thats why im askin
Title: Re: *URGENT* noob question....fr competition...
Post by: SmAsH on June 28, 2009, 01:47:52 AM
a microcontroller cannot control dc motors directly. the motors draw too much current and fry the pin.
they require an h-bridge or motor driver. a servo is basically a dc motor with a gearbox, motor driver and feedback in a small, neat package.
Title: Re: *URGENT* noob question....fr competition...
Post by: intwizs on June 28, 2009, 01:49:50 AM
so its possible to connect a motor driver to a couple of geared DC motors and make them run under a program right?---for any possible circuit?
thats all I need
Title: Re: *URGENT* noob question....fr competition...
Post by: SmAsH on June 28, 2009, 02:19:36 AM
yes, you can have a robot with an mcu, motors, wheels, motor controllers, sensors and a regulated supply.
Title: Re: *URGENT* noob question....fr competition...
Post by: intwizs on June 28, 2009, 02:22:03 AM
so do i look for something specific in the motor driver im gonna buy?
all of them come suited for 4 motors right?
Title: Re: *URGENT* noob question....fr competition...
Post by: intwizs on June 28, 2009, 05:09:41 AM
i cant find a motor driver that can support 4 motors and run on a toy RC.......
I found AVR based boards for controlling the bot
but I want to use my own microcontroller and I need the motor driver so that I wont have to use servos
What to DO?
Title: Re: *URGENT* noob question....fr competition...
Post by: SmAsH on June 28, 2009, 05:23:22 AM
please don't send me a pm asking me to reply to this post, there are other people who can answer too ;)
for most small robots two motors will do fine. check out the l298 or l298d.
if it is a robot why do you want rc? i think it will be quite useless for this project...
what do you mean by "your own microcontroller"? it would be easiest to use something like an atmega8 as in the $50 robot tutorial.
Title: Re: *URGENT* noob question....fr competition...
Post by: intwizs on June 28, 2009, 05:28:34 AM
alright....tis is helpful...i think i can go on wid tis mch info.....
ty soo mch.....
Title: Re: *URGENT* noob question....fr competition...
Post by: jamort on June 28, 2009, 10:43:27 AM
*URGENT*
you know every question you asked are answered in the basic tutorials on here give them a rad you may be suprised :P