Society of Robots - Robot Forum

General Misc => Misc => Topic started by: helmyshahryl on June 06, 2007, 08:13:56 PM

Title: Automated guided vehicle using line following concept
Post by: helmyshahryl on June 06, 2007, 08:13:56 PM
Hi...My name is Helmy...I would like to build an AGV that use a concept of line follower...My AGV or I wanna call it as LiDTrans(Line Detection Transporter) can go from one station for loading goods to another station to unload the goods before return back to the base. I would like to have 4 station which will be station A, B and C and also base station. If I have a junction, let say, if the LiDTrans instructed to go to station C, it must pass 2 junction which is junction for station A and B. Can you give me some ideas on how to detect that it is the junction for station A, B or C. One more thing, I will have a control panel at base station. The control panel will have a GUI for user to select where to load the goods and where to unload the goods, and the signal will be transmitted to the LiDTrans where the PIC will process the signal to navigate LiDTrans to go to load and unload station. All I'd mentioned above will be implemented in my Final Year Project and I am in the proposal stage right now. Can you please help me on the idea of my LiDTrans because it is very important for me. Thank you so much.

Regards,
Helmy Shahryl
[email protected]
[email protected]
Title: Re: Automated guided vehicle using line following concept
Post by: Kohanbash on June 06, 2007, 09:59:25 PM
A simple way to detect the points is by putting a hall effect or limit switch at each station. The problem with this is that you need a homing routine in the beginning since the station is relative based off counting ticks from each station. "smart" ways to do this is to use RFID tags to send out the actual station number or put metal prongs on each station representing the station number and have limit switches on the robot to sense the prongs. This can also be done using light sensors. For example with two limit/light sensors you can detect four positions: 00 01 11 10. (note the count is not in numerical order but is similar to a gray code where only one possible bit changes per location, this can be used to insure no error in sensing locations.

For the controller just send the position number and have logic to figure out direction of travel based from last position passed. Again you will need a homing routine or you can always start the robot from the same location.
Title: Re: Automated guided vehicle using line following concept
Post by: Ro-Bot-X on June 07, 2007, 12:00:14 AM
Something similar was done using Lego robots and Lego automated machines in 2003 by SMART group. Very impressive. It's called Cooperative Crate Contraption

Check out these videos (you need divx):

http://zx81.isl.uiuc.edu/lego/crates/Overview1.avi (http://zx81.isl.uiuc.edu/lego/crates/Overview1.avi) Overview 1 -  7.8Mb (length: 0:29.5)

http://zx81.isl.uiuc.edu/lego/crates/Overview2.avi (http://zx81.isl.uiuc.edu/lego/crates/Overview2.avi) Overview 2 - 13.7Mb (length: 0:52.0)

http://zx81.isl.uiuc.edu/lego/crates/Overview3.avi (http://zx81.isl.uiuc.edu/lego/crates/Overview3.avi) Overview 3 -  6.4Mb (length: 0:24.2)

http://zx81.isl.uiuc.edu/lego/crates/OverviewFast.avi (http://zx81.isl.uiuc.edu/lego/crates/OverviewFast.avi) - Sped up overview - 20.4Mb (length: 1:16.7)


And this year's contraption on youtube:

 (http://www.youtube.com/watch?v=bGmOAYqKSaU[/url)
Title: Re: Automated guided vehicle using line following concept
Post by: Admin on June 08, 2007, 12:57:34 PM
This sounds exactly like a competition at CMU called MOBOT (http://www.societyofrobots.com/competitions_mobot.shtml)

Basically robots follow lines to get to various goals (called gates), and if the line splits the robot must choose the correct path:
(http://www.vision.cs.chubu.ac.jp/~hf/IMG/CMU/013.jpg)

Google it for more.

There are also factories that actively use this robotic technology so is worth a google search on it.
Title: Re: Automated guided vehicle using line following concept
Post by: helmyshahryl on June 08, 2007, 07:56:55 PM
Hi,
If the line splits, how my robot going to determine the correct path?Is it predefined from the program...Is the use of sensors suitable for determine the correct path?...For the IR sensor that detect the line, do we need to have 3 sensors which 1 sensor is for detecting the line and the other 2 sensors for a guide if the car deviate from the line. Is it necessary? Or, if I just use 1 sensor, can I do a closed loop system?But then, I don't have idea on how to do a closed loop system for the line detection using 1 sensor.Same as zaryn's image processing, my project must be proposed within next week,and I really need your help regarding my line detection project.
Thank You...

Regards,
Helmy Shahryl
Title: Re: Automated guided vehicle using line following concept
Post by: iNFINITE on June 09, 2007, 07:02:46 AM
Hi Helmyl,

You can make a line follower with one sensor also, but it will not be a good follower. Normally 3-6 sensors are necessary to detect line splits, obtuse angle turns..
See this write up:http://www.wrighthobbies.net/guides/linefollower.htm (http://www.wrighthobbies.net/guides/linefollower.htm)