Author Topic: Sensor board for a small line follower  (Read 1661 times)

0 Members and 1 Guest are viewing this topic.

Offline ConscriptedTopic starter

  • Robot Overlord
  • ****
  • Posts: 291
  • Helpful? 10
Sensor board for a small line follower
« on: December 16, 2010, 11:55:35 AM »
I'm in the design phase of a small line follower. I found this sensor and wanted to know if it would be suitable to build the line tracking sensor. http://uk.farnell.com/osram/sfh7221-z/emitter-detector-ir-880nm-smd/dp/1219694.
The plan is to use:
  • Two pager motors
  • ATTINY85
  • SFH7221 (X3)
I'm planning on running the bot at 3vdc.

Conscripted

Offline waltr

  • Supreme Robot
  • *****
  • Posts: 1,943
  • Helpful? 98
Re: Sensor board for a small line follower
« Reply #1 on: December 16, 2010, 12:32:16 PM »
Nice small device. Looks like it should work.
It will probably take a little experimenting to find the optimal distance, LED current and phototransistor bias to get reliable results.

Offline ConscriptedTopic starter

  • Robot Overlord
  • ****
  • Posts: 291
  • Helpful? 10
Re: Sensor board for a small line follower
« Reply #2 on: December 16, 2010, 10:19:26 PM »
I could use some advice on how to use the photo transistors. I googled about a bit today but everything I found that may have given me information was blocked by the firewall. How do I connect these to the micro? Will it have to be through the ADC or can I get a simple digital input? A schematic would be great help.

Conscripted

Offline aruna1

  • Supreme Robot
  • *****
  • Posts: 381
  • Helpful? 4
  • I'm an Ordinary guy
Re: Sensor board for a small line follower
« Reply #3 on: December 17, 2010, 06:56:10 AM »
pager motors are power hungry buggers.will eat your battery in minutes.and they are hard to control
I'm Me

Offline ConscriptedTopic starter

  • Robot Overlord
  • ****
  • Posts: 291
  • Helpful? 10
Re: Sensor board for a small line follower
« Reply #4 on: December 17, 2010, 07:15:03 AM »
I'm ok with a relatively short battery life. This is just for my own improvement. I won't be going to a contest with it. I'm currently in south dakota. There aren't any competitions within a 5 hour drive from here.

What makes pager motors harder to control then a regular motor?

Conscripted

Offline aruna1

  • Supreme Robot
  • *****
  • Posts: 381
  • Helpful? 4
  • I'm an Ordinary guy
Re: Sensor board for a small line follower
« Reply #5 on: December 17, 2010, 08:31:47 AM »
well they just dont behave well. i guess they are not made to be controlled.just go wild and vibrate(due to attached weight of course).even with lo pwm useful speed is too high (from my experience) however if you can gear it ,it will be a different story
I'm Me

Offline ConscriptedTopic starter

  • Robot Overlord
  • ****
  • Posts: 291
  • Helpful? 10
Re: Sensor board for a small line follower
« Reply #6 on: December 17, 2010, 09:00:05 AM »
I'm looking at a pair of pager motors from www.solarbotics.com they don't have weights attached. They also sell geared pager motors.

Offline waltr

  • Supreme Robot
  • *****
  • Posts: 1,943
  • Helpful? 98
Re: Sensor board for a small line follower
« Reply #7 on: December 17, 2010, 09:11:54 AM »
I could use some advice on how to use the photo transistors. I googled about a bit today but everything I found that may have given me information was blocked by the firewall. How do I connect these to the micro? Will it have to be through the ADC or can I get a simple digital input? A schematic would be great help.

Conscripted

Think of the photo transistors as a regular NPN transistor but with light creating the Base current. The Collector and Emitter is connected as any other NPN.
You don't need an ADC if you design the photo transistor circuit correctly. What you want is the photo transistor is be either fully off on fully on (saturated) when the sensor is over a black or white surface. Then just connect to a digital input to be read as a '0' or a '1'.

 


Get Your Ad Here

data_list