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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
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
Joshua Wilkinson

Reading from Datalog Files - NI LabVIEW 8.6 Help - 5 views

zone.ni.com/...reading_datalog_files

datalog reading

shared by Joshua Wilkinson on 26 Jan 12 - No Cached
  • Bryan Kelleher on 26 Jan 12
     
    this shows how the data logs work ( ._.)
  • Alexander Laferriere on 26 Jan 12
     
    Nice (o____________________________________________________________________o)
  • Nick Laferriere on 26 Jan 12
     
    oooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo
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
Thomas Corcoran

Reading Microsoft Excel Numeric Data Into LabVIEW - National Instruments - 2 views

digital.ni.com/...F61B6AB9CD6AFA8625734600814D6B

shared by Thomas Corcoran on 02 Feb 12 - No Cached
  • Thomas Corcoran on 02 Feb 12
     
    converting .xls to .lvm
Anthony DiVirgilio

Read Ultrasound (cm) - LabVIEW 2009 LEGO MINDSTORMS NXT Module Help - National Instruments - 3 views

zone.ni.com/...sonar_cm

shared by Anthony DiVirgilio on 13 Oct 11 - No Cached
    • Anthony DiVirgilio
      Anthony DiVirgilio on 13 Oct 11
       
      here is a good code example for the ultrasonic sensor
  • Thaddeus McKeon on 13 Oct 11
     
    shows how to use basic ultrasonics in labview
Thomas Corcoran

Read PING))) Sensor Distance VI - LabVIEW 2011 Robotics Module Help - National Instruments - 0 views

zone.ni.com/...skit_read_ping

Ultrasonic sensor

shared by Thomas Corcoran on 13 Oct 11 - No Cached
  • Thomas Corcoran on 13 Oct 11
     
    teaches you how the ultra sonic sensor works
Thomas Helm

Sound sensor - 4 views

www.convict.lu/...NXT_sound_sensor.htm

shared by Thomas Helm on 13 Oct 11 - No Cached
  • Both LEGO™ NXT sound sensors were placed at the same distance from the speaker. A very simple LabVIEW NXT toolkit was run in debugging mode, in order to display the values on the PC screen and keep the NXT alive (Fig. 3). The frequency and the signal amplitude were gradually changed and the sensor readings were noted manually and entered into an Excel-file and also into a LabVIEW 3D-graph program (that we do not reproduce here). (Fig. 4 and 5) show the different graphs in 3D for the frequencies 100..1000Hz.
    • Anthony DiVirgilio
      Anthony DiVirgilio on 13 Oct 11
       
      we could use this to make the user have to do less to use the robot
  • Thomas Corcoran on 13 Oct 11
     
    Sound sensor with example code
  • ...1 more comment...
  • Alexander Laferriere on 06 Dec 11
     
    this is helpful
  • Declan Coen on 06 Dec 11
     
    This shows how the sensor will detect sound and then transmit it to the nxt
  • Bryan Kelleher on 07 Dec 11
     
    THIS WAS EXTREMELY HELPFUL
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