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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
Andrew Drogan

My Library - 2 views

www.diigo.com/andrewdrogan

ultrasonic sensor

shared by Andrew Drogan on 13 Oct 11 - No Cached
  • Andrew Drogan on 13 Oct 11
     
    if a light source is detected on the left of the robot, the left motor will speed and the robot will veer away from the light source.increahttp://gicl.cs.drexel.edu/wiki-data/images/7/72/LearningRoomba-SensorsActuators-StudentsGuide.pdfse
Joshua Wilkinson

iRobot Corporation: Customer Care - Service/Support - 0 views

homesupport.irobot.com/...491

homebase sensor

shared by Joshua Wilkinson on 17 Oct 11 - No Cached
  • The Roomba Remote, Virtual Wall, and Home Base operate using an invisible infrared technology.
  • Joshua Wilkinson on 17 Oct 11
     
    we could use light snesor to pick up light emitting from the homebase
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.
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

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
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
Thaddeus McKeon

NXT Radar - 1 views

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

radar

shared by Thaddeus McKeon on 02 Apr 12 - No Cached
  • Thaddeus McKeon on 02 Apr 12
     
    this nxt has been built to map things with a rotating light sensor
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.
Alexander Laferriere

color and light sensor - 2 views

digital.ni.com/...F4351695FC3A7386257707006E52EF

sensor sensors Ultrasonic robot detection wall obstacle iRobot NI sound

shared by Alexander Laferriere on 16 Oct 11 - No Cached
  • Alexander Laferriere on 16 Oct 11
     
    this shows how to use the color and light sensor
Declan Coen

Programming and Robotics - 2 views

www.extremities.com/...index.html

shared by Declan Coen on 15 May 12 - No Cached
  • Declan Coen on 15 May 12
     
    the video shows that when the light sensor reads a certain value then it pick it up...
  • Declan Coen on 15 May 12
     
    *initiates the motor to turn on which lifts up the object
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
Thomas Helm

Nxt - 7 views

www.ece.gatech.edu/...NXT%20lab%203.pdf

shared by Thomas Helm on 12 Mar 12 - No Cached
  • Thaddeus McKeon on 12 Mar 12
     
    this shows how to get an NXT to keep on the line where it should turn and all taht good stuff
  • Thomas Corcoran on 12 Mar 12
     
    shows different light sensor values you should get around when you are going off the tape
Thomas Helm

Light sensor and Ultrasonic thats it - 4 views

www.youtube.com/watch

shared by Thomas Helm on 03 Apr 12 - No Cached
  • Declan Coen on 05 Apr 12
     
    this could work but what if the robot turned and started going the wrong direction back towards the start???? it only follows the walls which could lead the robot back to the start not the finish
  • Thomas Helm on 05 Apr 12
     
    anyrobot we do is basically going to be folllowing the wall though and it would have to go all the way to the end to start going back to the beginning
Thomas Helm

Avoiding Falling off - 5 views

i agree a lot with declan, by how everyone is looking most people are going to be using ramps so im gonna try and find something better

light sensor

started by Andrew Drogan on 17 May 12 2 follow-ups, last by Thomas Helm on 17 May 12
Stephen Brogan

LEGO.com MINDSTORMS : Products - SENSORS - 9843 - 1 views

mindstorms.lego.com/...9843.aspx

sensors

shared by Stephen Brogan on 13 Oct 11 - No Cached
  • 9843 9844 9845 9846
    • Joshua Wilkinson
      Joshua Wilkinson on 13 Oct 11
       
      is it posssible to use at least two of these on the robot, or is there not enough ports on the nxt
    • Thomas Helm
      Thomas Helm on 13 Oct 11
       
      im very sure that you can use more than one sensor but ill see if i an find something on it now
  • The Touch Sensor reacts to touch and release, enabling your LEGO® MINDSTORMS® NXT robotic creation to "feel" like never before! It can detect single or multiple button presses, and reports back to the NXT Intelligent Brick
  • Stephen Brogan on 13 Oct 11
     
    Interactive sensor database
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