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ashish_agarwal123456
07-10-2008, 09:13 PM
hello friends,
i am planning to make a line follower which can run with speed 1m/s or more...... i am not clear of which hardwares to go for...... please help me out.....

MOTOR
dc geared motor or simple dc motor??
highest rpm for geared motors available here is 120rpm..... but main problem is that they are bulky,costly and big in size.......
simple dc motor are small, cheap, fast.... upto 2000rpm...... i can use external plastic gears..... but can they provide enough power?????i will be using smallest possible tyres.the weight of final robo is going to be around 400gm(excluding motors) if voltage requirement is below 6v.....

sensor
ir sensors or led+photodiode???
on the forums, i found people saying photodiodes are better for line follower..... but can they work fast??? also i do not want to use modulated wave for sensors..... i think ir sensors require modulated wave to work properly. also i am not sure whether they are absobed properly by black line or not?? ..... if you could suggest any other sensor also???? i will be using 5 sensor array.... my requirements include fast response (so no ldr), easy to use and cheap......
also tell me do i need to convert the output of sensor to digital form of 8bits..... i mean can't we use their output of 1 bit.... high if line present(/absent) below it and low if line absent(/present) below it... because here we do not want to calculate the distance..... does converting to 8bit digital form has any advantage...... i can increase the array to 7 if required.....

brain
pic or avr or 8051 family
i dont have any programmer so i need it also...
8051 family is cheap, easy to use, large no of i/o pins but its programmer is to complex to built and too costly to buy.......
avr are a little costly, complex, but programmer is cheap and affordable by me....... for avr i think atnega8 will be best candidate..... cheaper, enough memory, 2 pwm for motors.....
what about pic.... i have never worked with them..... from my search i dont see much difference between pic and avr..... but how to program it???? also which series will be suitable??


specifications for my project are:
1) fast speed:1m/s on straight tracks
2) able to take sharp and acute angle turns
3) i will be using pid algo so need resouces for it in uc
4) uc should be able to provide pwm for two motors
5) the only source for finance for me is my pocket money, so i want the project to be completed within 1000-1500 Rs. in which i have to buy all components, programmer kit, and a multimeter(as i just passed out from college so no help from that side)..... i have ni-cd batteries so no expense for them......

any other suggestions for this project are also welcome..... specially for mechanical assembly(i am not even good in it) :( ...... any do's and don't......

thanks.......

docel
07-11-2008, 12:42 AM
1. We have several 300RPM x 16.8cms wheel circumference LFRs that are winning prizes all over India..........!

NONE of them have a Microcontroller!!!

2. Its time you guys realised this: You go for a Microcontroller and you will be slow ( or never in a competition, or away from Robotics for ever ) :roll:

My students design, make, run & optimise LFRs and Grid navigators, according to problem statements in one day.

Why is it that people always think that a Micro is the ONLY way to do these things?
I pity the guys "struggling" to Program a micro to do a simple job of a basic 4-input-4output logic.

3. For that money, you wont even 'see' good geared motors, except the inefficient junk sold all over the country by Vegakit and others.
These will never allow you to achieve half of what you are planning for.

Its time you guys thought of other easily achievable ways than get stuck with the unnecessary hassles of a micro.......no matter what your seniors or anyone else says that a Microcontroller is THE ONLY way to Robotics!

ashish_agarwal123456
07-11-2008, 10:32 AM
i know replacing hardware with software decreases processing speed..... but the thing is that a micro can be programmed many times so same micro can be used in different projects....... if i invest in digital ics then they will be soldered and so unusable any further..... as i am a hobbyist only, not making robo for any competition, i prefer something reusable........


for the motors what would you suggest...... i saw a 300rpm motor on online tps..... http://www.onlinetps.com/ShowCategory.php?CategoryID=14 ...... will they work??????

shashak
07-11-2008, 10:54 AM
@ ashish

if i have to build on these specs and budget.

for motor i would have hack china made tank toy
for sensors i use would IR pair.
for mcu i would use mega8 with avr studio + ponyprog.
and standard PP3 9 volt batteries, would buy 2 box of 10. one battery of each run.

@docel
making robot with just simple logic is means leaving them to work on there instincts just like insects. And i feel the same for beam robots. i hope i had not offended feeling of beamers :)

The use of micro is inevitable for robotics, as it make robots/ machine more useful and versatile. beam and all simple logic are good for only specific functions/tasks.

Nivedita
07-11-2008, 02:08 PM
3. For that money, you wont even 'see' good geared motors, except the inefficient junk sold all over the country by Vegakit and others.
These will never allow you to achieve half of what you are planning for.


I am always guessing the way of manufacturing these motors.

Are these motors reused one?

Do you have a good resource for motors?

ashish_agarwal123456
07-11-2008, 02:55 PM
thanks shashak

but i can't figure out what u meant by "hack china made tank toy"...... do you mean motors which come in china made toys or they are something special....... if so where i can find them?????

also i want a schematic for atmega8 programmer kit...... i tried it for my previous project also... but there are many circuits available on net and each of them say that the circuit is compatible with ponyprog..... how ponyprog will determine which circuit i am using.... if you have any sure-shot circuit plese send me a link to it or mail me......
ashishfriend2002@yahoo.com

and for the sensors..... i have a ir-tx-rx pair....but i cant make them work..... can i use them without modulated wave???? i mean in the way we use led+ldr????? also how to make sure ir-led is emitting light..... they r not visible to my mobile camera..... i havent tried with laptop but it also has same type of camera.......


thanks......

ashish_agarwal123456
07-11-2008, 03:49 PM
and the award for doing world's most silly mistake goes to------ ASHISH AGARWAL.....

yes, for the last 3 months i am trying to make my ir-led-photodiode work. today i get to know that the led like structure with clear transparent casing is actually photodiode and the led like structure with dark blue casing is actually ir-led..... :D ( i was thinking the other way and it don't even come to my mind once that it can be wrong)....

i dont remember where i read that ir-photodiodes are packed in dark casing to filter visible light...... also the ir-emitter present in my remote control is tranparent....... maybe their is not a fixed standard....

and yes, now its visible from mobile camera.... and the sensor is working great for line detection......

so now i have only two problems remaining ..... lets hope they r solved soon......

bye....

ashish_agarwal123456
07-11-2008, 07:39 PM
thanks again shashak

well, i found many circuits for programming atmega from parallel and serial port...... i was just curious to find a circuit to program atmega using USB..... but couldn't find any..... is it something TOP SECRET :P :P

where can i find affordable usb atmega programmer...... i just want programmer, not the development board....

virgo
07-12-2008, 01:20 PM
nothing top secret , it is all open

visit the following link for circuit of usb programmer
http://www.fischl.de/usbasp/

Happy line following. :lol:

maddy_nish
07-16-2008, 01:19 PM
The following idea would give you good speed along with average torque. My robot runs at 120 cm/s.

First of all do not use a 300rpm motor or a faster one directly.Purchase a 60 rpm motor and remove the gears till u have only one gear train between the driving shaft and driven.
Now your motors are ready which can give you satisfactory speed and torque.Whatever may be the speed a matching torque is required to drive the robot efficiently. Hence the above motor design would give you good speed but low torque. Now if a high frequency pwm of duty cycle approx 80% would give the required torque and moderate speed to your robot. Such a motor can be efficiently controlled via a micro controller to give speeds as high as 120cm/s. Several experiments were conducted before setting the optimum frequency and duty cycle of the driving pwm.

asimov_18
07-16-2008, 09:35 PM
Hi as docel mentioned..........same mistakes again and again........ppl are in a hurry to get into robotics and electronic....for show off and marks.........end up falling on their face...........start making simple ckts.....frankly i too love micros ....sorry docel for this but I find it(uC) like a blank slate on which I can draw anything.......BUT PPL START BY MAKING SIMPLE OPAMP CIRCUITS..........THen MOVE TO ALL THIS STUFF........


asimov

ashish_agarwal123456
07-17-2008, 09:19 AM
i have mentioned my specs and yes i will be using uC (for some resons i have already mentioned).... so why not keep our focus in that direction only????

[Edited]

samurai_01
07-25-2008, 03:18 PM
http://www.robotroom.com/Jet.html
please see this site.it has very nice explaination of what you want to build, with component specifications.
you may use this site for reference

alphageek
02-15-2009, 04:10 AM
an ir-phototransitor pair can also be used as the sensing module wiyh good results...the action of the phototransistor is unaffected by visible light..!

allbits
02-15-2009, 08:27 AM
.the action of the phototransistor is unaffected by visible light..!


Thats a mis concept - it depends on the type of transistor you are you are using.

Take your transistor, wire it, and light it up straight into its lens, and see the deftection in a CRO or a DMM. !!!

The responce to different wavelengths of light for each phototransistor will be mentioned in the datasheet. Read them and see which one suits you the most!!!

alphageek
02-15-2009, 03:39 PM
i mayb wrong...bt it works for me flawlessly...i think visible light is nt gonna make much of a difference in its action..am i right?