Fast Line Tracer Robot (2nd attempt) - Lego Mindstorms NXT 2.0

[Myrsloken3]

nice

[AzNoelle493]

pretty good

[MrAlimurka]

How did you make it go so fast?

[thePavuk]

Nice and smooth with one sensor. Good parametrs. We use tighter line for student competitions and bigger wheels, so they have to use more sensors.

[SkipperWordPress]

If you programme it correctly it will drift itself,because at the corner when it goes straight the sensor will see the white place,but as I said if you programme it correctly,it will only go on anything black.Its so simple...it took our 15 minutes at school to do.

[antoniono95]

I still don't get, how did you programmed it to know when to turn lef or right? how can the robot distinguish the situation, to know wich side it will turn??

[pandalori]

@antoniono95 Take a look at the tutorial on techbricks.nl on how to build a line tracer robot using a PID controller. This method uses a feedback loop and calculates the error value relative to a setpoint. The program then adjusts the robot to minimize the error. So effectively, when the error gets larger and larger, the program will know to turn the other way to keep on course.

[dolah1995]

Erm.... Can this same line tracing be done using a normal NXT light sensor ?

Im very interested to learn how you program such a fast line tracing NXT robot.

May i request that you share the logic of the line tracing program ?

I would really appreciate it if you do.

[pandalori]

@dolah1995 Yes, it can be done using a normal NXT light sensor, but the implementation is more of a hack. I can send you the link to a similar implementation on a website I used.

[MacWii]

Well, i am as well interested on knowing on how you made the program, we are going to make a robot for a competition. and this program could be handy. if you happen to have a copy of the program of this robot, would you please let a download link for it?

Thanks in advice

[pandalori]

@MacWii You can take a look at techbricks.nl where they explain how to implement a PID controller and I found that implementation works very well too.

[MrSwiss313]

@pandalori Nice project! Did u programm it with the "normal" Software from LEGO? I hope u answer, it's really important!

[pandalori]

@MrSwiss313 No, I didn't use the software that came with the Lego kit. I used a C like programming language called NXC.

[robojove]

ey whats up i saw u line following robot can u lend me the program that u use? i want to do something like this thanks so much

[pandalori]

@robojove You can take a look at techbricks.nl where they explain how to implement a PID controller and I found that implementation works very well too.

[jjdogman170]

how did u make it to go straight

cause mine still goes zig zag line 

[pandalori]

@jjdogman170 I used a state machine where if the robot detects that it doesn't require any turning for a while, then the two motors are set to be the same power for it to go straight.

[levibowhunter]

How did you program the sensor to know the colors and to turn right and left?

right now i am using nxt 2.1 programmer for the lego mindstorm and we have it following a line but it will only make left turns and not right turns. what should i do?

[pandalori]

@levibowhunter I used NXC to program the color sensor. If you are using NXT-G there is a pretty good implementation and explanation on this site that I found. I'll email you the link.

[GMSamuelRhine]

@pandalori could you email me the link to get my bot to line trace too?

[123456bnys]

wow put loop

[lamzhiyuan]

How did you program it?

[pandalori]

@lamzhiyuan I programmed it with NXC, a C like language. It is also possible to program it with LabVIEW, the graphical flow-chart like software that came with the NXT set.

[lamzhiyuan]

@pandalori What I mean is, how did you get the robot to know whether to turn left/right when it sees white?

[pandalori]

@lamzhiyuan The color sensor shines red, green, and blue light. When the robot goes off course and slightly to one side, it would detect one of the colors. So the robot is able to distinguish between the left side and the right side and turn appropriately.

[RoboticsLearning]

@pandalori Very clever, I never would have thought to use the offset of the color LEDs to detect the sensor position. I will use this idea, thanks! :-) Steve Putz, Robotics Learning

[8597465]

@lamzhiyuan the robot doesn't really follow the line, it follows the edge of the line = to dark turn left, to bright turn right, this programmed with a PID-Controller (a formula witch compensate errors) and the robot can follow lines very nice and fast

[hydrogenhead]

@pandalori: I do not believe you can use LabVIEW for this application, since it allows only one color lamp to illuminate at a time and can't switch back and forth quickly enough to be of use. I guess I'll have to learn NXC!