Author Topic: small robot help-urgent  (Read 910 times)

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Offline aruna1Topic starter

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small robot help-urgent
« on: August 22, 2010, 09:00:58 AM »
guys I'm making a tiny line follower robot. it is a basic line following with two transistors.I use two pager motors and rubber wheel on cassette players as wheels.my question is this robot it too fast therefor it cant respond to line accordingly. there is no motor speed control mechanism implemented.can some one please tell me how to slow this down without making a big circuit?
a transistor based pwm circuit will be great i guess.I'm posting the circuit I'm using

I'm in hurry as I'm making this for an exibition and date is getting closer

thank you

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Offline Soeren

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Re: small robot help-urgent
« Reply #1 on: August 24, 2010, 07:15:53 PM »
Hi,

my question is this robot it too fast therefor it cant respond to line accordingly. there is no motor speed control mechanism implemented.can some one please tell me how to slow this down without making a big circuit?
a transistor based pwm circuit will be great i guess.I'm posting the circuit I'm using
A diode (or more) in series with the motor(s) should help. A resistor in series with the motor(s) would work too.


I'm in hurry as I'm making this for an exibition and date is getting closer
Aren't you always?  ;D
Why on earth don't you start a little earlier?
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline aruna1Topic starter

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Re: small robot help-urgent
« Reply #2 on: August 24, 2010, 07:18:54 PM »
well sorry for urgency.they always asked me to built them at the last moment, and with this academic load its really hard to allocaate time for robots  :(

by the way can you suggest me a small h bridge ic that contains 2 full bridges in 8 pin package?
thank you
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Offline cyberfish

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Re: small robot help-urgent
« Reply #3 on: August 25, 2010, 09:03:13 PM »
Can I get an 1 pin AND gate?

1 full bridge requires 4 inputs. 2 requires 8.

Where does power come from?

Offline Soeren

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Re: small robot help-urgent
« Reply #4 on: August 26, 2010, 06:11:27 AM »
Hi,

by the way can you suggest me a small h bridge ic that contains 2 full bridges in 8 pin package?
Nobody can.
2 full bridges takes (at least): 4 inputs, 4 outputs and 2 power lines.
I don't know of a 10 pin device either and since you didn't mention what voltage and current you need, I cannot point you to anything at all.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline aruna1Topic starter

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Re: small robot help-urgent
« Reply #5 on: August 26, 2010, 07:12:51 AM »
oh, i use 3.6v nimh battery and current is about 90mA per each motor
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Offline blackbeard

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Re: small robot help-urgent
« Reply #6 on: August 26, 2010, 07:24:29 AM »
Hi,

by the way can you suggest me a small h bridge ic that contains 2 full bridges in 8 pin package?
Nobody can.
2 full bridges takes (at least): 4 inputs, 4 outputs and 2 power lines.
I don't know of a 10 pin device either and since you didn't mention what voltage and current you need, I cannot point you to anything at all.


actually the l293d is a quad half H bridge IC in an 8 pin package. it's actually pretty good and it can control 2 motors independently

edit: DOH >.< i was thinking 16
« Last Edit: August 26, 2010, 07:25:40 AM by blackbeard »
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Offline aruna1Topic starter

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Re: small robot help-urgent
« Reply #7 on: August 26, 2010, 07:25:37 AM »
Hi,

by the way can you suggest me a small h bridge ic that contains 2 full bridges in 8 pin package?
Nobody can.
2 full bridges takes (at least): 4 inputs, 4 outputs and 2 power lines.
I don't know of a 10 pin device either and since you didn't mention what voltage and current you need, I cannot point you to anything at all.

nope it has 14 pins

actually the l293d is a quad half H bridge IC in an 8 pin package. it's actually pretty good and it can control 2 motors independently
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Offline knossos

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Re: small robot help-urgent
« Reply #8 on: September 11, 2010, 01:40:38 AM »
guys I'm making a tiny line follower robot. it is a basic line following with two transistors.I use two pager motors and rubber wheel on cassette players as wheels.my question is this robot it too fast therefor it cant respond to line accordingly. there is no motor speed control mechanism implemented.can some one please tell me how to slow this down without making a big circuit?

Well, a simple way would be smaller wheels.  Not sure how small your line follower is, but a great idea for small wheels can be found on some of the beetle bots.  Use the motor shaft itself as the wheel, you can even put some heat shrink on it for more traction.  Also changing the angle of the motor will change speed of the robot: the closer the motors are to being parallel to the ground, the faster the robot goes.

I'm in hurry as I'm making this for an exibition and date is getting closer

Hope this doesn't come too late.  I'm curious to hear what solution you used.
« Last Edit: September 11, 2010, 01:41:58 AM by knossos »
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