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Declan Coen

PID Controller For Lego Mindstorms Robots - 7 views

www.inpharmix.com/...or_Lego_Mindstorms_Robots.html

pid nxt

shared by Declan Coen on 12 Mar 12 - Cached
  • light sensor "sees white" then we know it is left of the line's edge (and the line). If it "sees black" then we know it is to the right of the line's edge (and on the line). This is called a "left hand line follower" since it is following the line's left edge
  • We need to know what values the light sensor returns when it "sees white" and when it "sees black". A typical uncalibrated sensor might give a "white" reading of 50 and a "black" reading of 40 (uncalibrated, on a 0 to 100 scale). It is convenient to draw the values on a simple number line to help visualize how we convert light sensor values into changes in the robot's movement.
  • Below are our made up light values for white and black.
  • ...4 more annotations...
  • We'll just divide the range into two equal pieces and say that if the light level is less than 45 we want the robot to turn left. If it is greater than 45 we want to turn right. I won't go into how exactly the turns should be done. I'll just say that gentle turns work well for a fairly straight line
  • line with lots of curves usually needs to be making sharper turns. For gentle turns you might use Power levels of 50% on the fast wheel and 20% on the slow wheel. For sharper turns on a curvy line you might need to use 30% power for the fast wheel and coast or brake the slow wheel. Whatever power levels you use the numbers will be the same for the two turns, you just switch which motor gets the big number and which get the smaller number (or a stop command).
  • This type of a line follower will follow a line but it isn't very pretty. It looks OK on a straight line with with the motors programmed for gentle turns. But if the line has any curves then you have tell the robot to use sharper turns to follow line. That makes the robot swing back and forth across the line. The robot only "knows" how to do two things; turn left and turn right. This approach can be made to work but it is not very fast or accurate and looks terrible.
  • In the above approach the robot never drives straight, even if it is perfectly aligned with line's edge and the line is straight. That doesn't seem very efficient does it? Lets try to fix that. Instead of dividing our light value number line into two regions lets divide it into three.
  • Anthony DiVirgilio on 12 Mar 12
     
    seems useful for following a line effectively
  • ...1 more comment...
  • Thomas Corcoran on 12 Mar 12
     
    this is a really good technique
  • Declan Coen on 12 Mar 12
     
    the top of this article explains how it would be easier to follow the edge of the line rather than the center of the line. As it detects the white it will turn back to the black and as it detects the black it will turn back to the white.
  • Thomas Helm on 12 Mar 12
     
    i found the edge thing on another site too
Thomas Helm

LINE - 4 views

Line Following In Chapter 3, we talked about going straight and having a well-tuned robot. I mentioned using the field environment for help in traveling a straight line, such as running along the...

started by Thomas Helm on 12 Mar 12 no follow-up yet
Joshua Wilkinson

NXT Line Follower - 2 views

www.nxtprograms.com/...steps.html

shared by Joshua Wilkinson on 12 Mar 12 - No Cached
  • When line following, the robot will try to align itself centered over the boundary between white and black (not centered over the black line), with black to the robot's left.  Here the brightness seen by the sensor is halfway between the black/min and white/max readings
    • Joshua Wilkinson
      Joshua Wilkinson on 12 Mar 12
       
      This would be useful since we get the value when its over the tape and table, we can also find the value of the sensor when its directly over the tape then the table seperately.
  • When prompted to sample the "Min" or "Black" reading, position the sensor so that the red spot is centered over the line and then press the Enter button on the NXT. When prompted to sample the "Max" or "White" reading, position the sensor so that the red spot is completely over the surface away from the line and press the Enter button on the NXT.
  • Andrew Drogan on 12 Mar 12
     
    Before line following using either the LineFollow2 or LineFollow5 program, you should "calibrate" the light sensor to the actual conditions expected. With the sensor mounted on the robot where it will be used, and the robot placed over the actual line it will be following, a calibration process takes two light sensor readings, one directly over the line (minimum = darkest), and one over the surface away from the line (maximum = brightest).
  • Declan Coen on 12 Mar 12
     
    if we follow the edge of the line we will always be between the max and the minimum values. therefore, it can detect both values and stay between the min and the max.
  • Thomas Helm on 12 Mar 12
     
    we have to figure out how to correctly calibrate the sensors
Anthony DiVirgilio

Fuzzy Line Following NXT Robot - 5 views

stefans-robots.net/...zy-line-follwing-nxt-robot.php

following line nxt robot

shared by Anthony DiVirgilio on 12 Mar 12 - No Cached
  • Bryan Kelleher on 12 Mar 12
     
    One of the tutorials within the Lego Mindstorms NXT Software shows how to program a robot that follows a line using Boolean Logic. In the following, an improved version, based on Fuzzy-Logic, is presented. Although a little bit more complex, the program is still implemented using NXT-G Code.
  • Anthony DiVirgilio on 12 Mar 12
     
    this has some good ideas
Thomas Helm

Line Follower - LabVIEW for Lego MINDSTORMS Projects - 3 views

sites.google.com/...line-follower

shared by Thomas Helm on 12 Mar 12 - No Cached
  • 3. In case the lighting in the room changes, could you program your line follower to re-calibrate the light sensor when you push a button?
    • Thomas Helm
      Thomas Helm on 12 Mar 12
       
      could b useful later on to look into
  • Thomas Helm on 12 Mar 12
     
    Tufts University Center for Engineering Education and Outreach In this activity, we will learn how to create a robot that follows a line on the ground. It will use one light sensor to sense where the line is, and use this to control the motors to steer the car and stay on the line.
Thomas Corcoran

Robots, mazes, and subsumption architecture - 3 views

www.ibm.com/...j-robots

shared by Thomas Corcoran on 02 Apr 12 - No Cached
  • Wall-following is a simple maze algorithm you might have learned as a child. All you do to solve a maze using this algorithm is keep your left hand on the left wall (or your right hand on the right wall) and just follow it along until you exit the maze. It's easy to see that this algorithm always works if the maze you're in has an entrance and an exit on its border. However, if the goal is within an island — a part of the maze that's disconnected from the rest of the maze — this algorithm can't find a solution because it can't "hop" over to the island.
  • has only its exterior walls and "growing" walls inward
  • Thomas Corcoran on 02 Apr 12
     
    wall following
  • Thaddeus McKeon on 02 Apr 12
     
    it works but there is no way we complete it in a minute
Andrew Drogan

Single Sensor « The Roboticist - 4 views

www.theroboticist.org/...single-sensor

shared by Andrew Drogan on 12 Mar 12 - No Cached
  • Andrew Drogan on 12 Mar 12
     
    In this setup, a single light sensor is positioned on the robot and programmed to follow the outer-edge of a black line. We commonly refer to the robot executing a 'Z' pattern while following the black line.
  • Thomas Helm on 12 Mar 12
     
    a z pattern might not b the best idea on this because we have a certain time we have to do
  • Declan Coen on 12 Mar 12
     
    if we keep it between a very specific max and minimum then it will not zig zag as much and will appear to go straight
Thaddeus McKeon

NXT Line Follower - 1 views

www.nxtprograms.com/...index.html

sensor detection

shared by Thaddeus McKeon on 12 Mar 12 - No Cached
  • Thaddeus McKeon on 12 Mar 12
     
    yet another NXT line follower bot using the light sensor
Andrew Drogan

Wall Follower - Top View - YouTube - 2 views

www.youtube.com/watch

view wall Follower

shared by Andrew Drogan on 13 Oct 11 - No Cached
  • Andrew Drogan on 13 Oct 11
     
    Another great video for wall detectio using the ultrasonic sensor.
  • Declan Coen on 16 Oct 11
     
    this is a great video because it enables the robot to keep track of the wall it is following and be on the look out for other walls to trace. this could also work for us because we have 3 motors: 2 for drving and turning and 1 for the ultra- sonic sensor
Alexander Laferriere

wall following - 4 views

www.youtube.com/watch

wall followind sensors sensor obstacle detection

shared by Alexander Laferriere on 13 Oct 11 - No Cached
  • Alexander Laferriere on 13 Oct 11
     
    this shows the wall following in action
  • Declan Coen on 16 Oct 11
     
    this is a good design for our robot because it has the sensor on the side for wall following and it has a touch sensor on the front which tells it to turn
Anthony DiVirgilio

NXT Line Follower - 8 views

www.nxtprograms.com/...steps.html

sensors detection

shared by Anthony DiVirgilio on 17 Oct 11 - Cached
  • Thaddeus McKeon on 17 Oct 11
     
    shows how to build a robot that follows lines.
  • Thomas Corcoran on 08 Mar 12
     
    line follower
  • Thomas Helm on 08 Mar 12
     
    All we would have to do is change those razor things out
Thaddeus McKeon

RoboCup Rescue Basic Line Follower.pdf (application/pdf Object) - 1 views

www.robocupjunior.org.au/...%20Basic%20Line%20Follower.pdf

line follower sensors detection

shared by Thaddeus McKeon on 12 Mar 12 - No Cached
  • Thaddeus McKeon on 12 Mar 12
     
    this is kind of a weird way of straddling the line but it works
Andrew Drogan

Lesson on how to follow the line - 3 views

www.comp.dit.ie/...Sensing_LineTracking.pdf

shared by Andrew Drogan on 12 Mar 12 - No Cached
  • Thomas Corcoran on 12 Mar 12
     
    this gives you a good strategy to find the line after you fall off
  • Andrew Drogan on 12 Mar 12
     
    This lesson will help you to follow the line better and more efficiently
Bryan Kelleher

LEGO.com MINDSTORMS : Community : NXTLOG - 4 views

us.mindstorms.lego.com/...DisplayProject.aspx

sensor

shared by Bryan Kelleher on 02 Apr 12 - No Cached
  • Bryan Kelleher on 02 Apr 12
     
    the way the ultra sonic sensor is set up is a good idea
  • Thaddeus McKeon on 02 Apr 12
     
    I feel the way they set up the light sensor is a little to far out
  • Joshua Wilkinson on 02 Apr 12
     
    we are gonna have to place the ultrasound or light sensor under three inches if we are following the inside walls, but thats an individule decsion. we could use a code similar to the wall following code in the romba project.
Jarid Brogan

Roomba Wall Following - YouTube - 1 views

www.youtube.com/watch

shared by Jarid Brogan on 21 Dec 11 - No Cached
  • Jarid Brogan on 21 Dec 11
     
    great wall following presentation
Declan Coen

electricbricks » Line Follower in LabVIEW. State Machines - electricbricks - ... - 6 views

blog.electricbricks.com/...lineas-labview-maquinas-estado

line follower

shared by Declan Coen on 08 Mar 12 - No Cached
  • Declan Coen on 08 Mar 12
     
    this is a possible way we can program the line folllower excluding the ultrasonic sensor
  • Thomas Corcoran on 12 Mar 12
     
    you can use the ultra sonic sensor for the maze bot later
Anthony DiVirgilio

Wall Follow Behavior Demonstration - YouTube - 5 views

www.youtube.com/watch

shared by Anthony DiVirgilio on 13 Oct 11 - No Cached
    • Anthony DiVirgilio
      Anthony DiVirgilio on 13 Oct 11
       
      the wall following robot is much more efficient in its cleaning
    • Thomas Helm
      Thomas Helm on 13 Oct 11
       
      it shows how it knows what to do near a wall
  • Andrew Drogan on 13 Oct 11
     
    great video for wall detection and how the robot will make its way through obstacles.
  • ...1 more comment...
  • Jarid Brogan on 13 Oct 11
     
    very good demenstartion and helped me understand how the wall detection move
  • Declan Coen on 13 Oct 11
     
    it helps show how the robot will travel until it reaches a wall to clean. Then from there it continues to travel along the wall until it is clean. Also, it helps show the perimeter of the room.
  • Alexander Laferriere on 17 Oct 11
     
    it looks like the grey one has something wrong with it
Anthony DiVirgilio

http://drgraeme.net/DrGraeme-free-NXT-G-tutorials/Ch102/Ch102V1G/default.htm - 0 views

drgraeme.net/...default.htm

motion following line

shared by Anthony DiVirgilio on 12 Mar 12 - No Cached
  • light sensor moved towards, and then away, from the line edge, (and then again towards, and then away, and so on…) as shown in the two photos below.
  • Thaddeus McKeon on 12 Mar 12
     
    I know we don't have 2 light sensors but it is nice to know one way of doing it
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