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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
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
Joshua Wilkinson

data log labview - 1 views

1.Click the Select a VI icon or text on the Functions palette. 2.Navigate to the VI that logged the front panel data and place it on the block diagram. 3.Right-click the VI and select Enable Da...

labview

started by Joshua Wilkinson on 26 Jan 12 no follow-up yet
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
Andrew Drogan

HowStuffWorks "Roomba Navigation" | Diigo - 1 views

www.diigo.com/...s%2Fhome%2Frobotic-vacuum2.htm

howstuffworks

shared by Andrew Drogan on 13 Oct 11 - No Cached
  • Andrew Drogan on 13 Oct 11
     
    When Roomba knocks into something, its bumper retracts, activating mechanical object sensors that tell Roomba it has encountered an obstacle. It then performs (and repeats) the sequential actions of backing up, rotating and moving forward until it finds a clear path.
  • Thomas Corcoran on 13 Oct 11
     
    I like how this shows all the different types of sensors and where they are, and what path the roomba takes
Thomas Corcoran

obstacle avoidance - 5 views

jvc.sagepub.com/...1077546310372004.abstract

obstacle

shared by Thomas Corcoran on 17 Oct 11 - No Cached
  • In this study, a path correction and obstacle avoidance method for a bipedal intelligent robot, using an ultrasonic sensor and electronic compass sensor, is proposed. The proposed method is implemented on an autonomous humanoid robot (the ARSR) comprised by the Lego NXT Intelligent Bricks. One ultrasonic sensor and one electronic compass sensor are installed on the ARSR to detect environmental information including obstacles, the distance to the obstacle, and the directional angle of the robot. Based on the obtained information, an obstacle avoidance and path correcting method is proposed to decide the ARSR’s behavior so that it can avoid obstacles automatically and move effectively to the destination area. Three obstacle avoidance experiments are carried out to confirm the effectiveness of the proposed method.
  • Thomas Corcoran on 17 Oct 11
     
    what to use for obstacle avoidance
  • Bryan Kelleher on 18 Oct 11
     
    I think this is a good idea!
Thomas Corcoran

NXT Top Spinner - 3 views

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

gears and construction

shared by Thomas Corcoran on 06 Dec 11 - No Cached
    • Thomas Corcoran
      Thomas Corcoran on 06 Dec 11
       
      could be really fun to build
    • Andrew Drogan
      Andrew Drogan on 06 Dec 11
       
      Great info
  • Thomas Corcoran on 06 Dec 11
     
    gears and construction on how to get high speeds
  • Joshua Wilkinson on 06 Dec 11
     
    This wouldn't work going up hill at 22.5 degress, and how would we get the nxt brick and the rest of the body to move that fast??
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
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
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
Anthony DiVirgilio

Roomba - Wikipedia, the free encyclopedia - 3 views

en.wikipedia.org/Roomba

shared by Anthony DiVirgilio on 13 Oct 11 - Cached
    • Anthony DiVirgilio
      Anthony DiVirgilio on 13 Oct 11
       
      these are some behaviors we could try to program our robots to do
  • generation models have a self-charging homebase they automatically try to find (via its infrared beacons). Charging on the homebase takes about three hours. All second and most third-generation Roombas can be used with the homebase, even if they do not come packaged with it.
  • Four infrared "cliff sensors" on the bottom of the Roomba's bumper prevent it from falling off ledges such as the top steps of stairways. Most second- and third-generation models have internal acoustic-based dirt sensors that allow them to detect particularly dirty spots (zones having excess particulates) and focus on those areas accordingly.
  • Stephen Brogan on 13 Oct 11
     
    Roomba descr with functions and hows
Declan Coen

HowStuffWorks "Roomba Navigation" - 2 views

electronics.howstuffworks.com/...robotic-vacuum2.htm

shared by Declan Coen on 13 Oct 11 - No Cached
  • While Roomba is cleaning, it avoids steps (or any other kind of drop-off) using four infrared sensors on the front underside of the unit. These cliff sensors constantly send out infrared signals, and Roomba expects them to immediately bounce back. If it's approaching a cliff, the signals all of a sudden get lost. This is how Roomba knows to head the other way
    • Anthony DiVirgilio
      Anthony DiVirgilio on 13 Oct 11
       
      this is how the roomba detects cliffs
  • Roomba can clean for about two hours on a single charge. If you have the self-charger, Roomba will return and connect to the charger all by itself when the battery power is low (the self-charger is sold as an add-on to the Roomba base model but comes included on most of the higher Discovery models). It accomplishes this using the infrared receiver on its front bumper. When the battery power gets low, the vacuum starts looking for the infrared signal emitted by the charger. Once it finds it, Roomba follows the signal and docks itself to the charger. Some robotic vacuums with this self-charging feature will head back out to resume cleaning once they're fully recharged
  • Declan Coen on 13 Oct 11
     
    this shows why cliiff sensors are needed and how they work
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

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 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

Something to use - 6 views

www.youtube.com/watch

shared by Thomas Helm on 03 Apr 12 - No Cached
  • Thomas Helm on 03 Apr 12
     
    This is im pretty sure everything we have
  • ...2 more comments...
  • Alexander Laferriere on 05 Apr 12
     
    i think that this is a great idea
  • Declan Coen on 05 Apr 12
     
    this would probably work very well and if we added a touch sensor *i dont know if they had one* which would activate the ultrasonic sensor and it would search and pick a path
  • Thomas Helm on 05 Apr 12
     
    That was a good idea declan thanks buddy
  • Declan Coen on 05 Apr 12
     
    OK 0_0
Declan Coen

Data acquisition with NXT and LabVIEW - Robota - 4 views

robota.das.ufsc.br/...quisition_with_NXT_and_LabVIEW

data

shared by Declan Coen on 26 Jan 12 - No Cached
  • Declan Coen on 26 Jan 12
     
    it explains how the block diagram needs to be set up to collect data and then input it to the computer
Anthony DiVirgilio

iRobot - cliff detection - YouTube - 2 views

www.youtube.com/watch

shared by Anthony DiVirgilio on 13 Oct 11 - No Cached
    • Anthony DiVirgilio
      Anthony DiVirgilio on 13 Oct 11
       
      This is a good video to show how the cliff detection works
  • Declan Coen on 13 Oct 11
     
    it shows how the roomba uses the infared sensors to detect cliffs and dropoffs. the robot expects to recieve signals from the floor and if the signals take too long to get back to the robot such as driving over stairs, the roomba will stop and go in a different direction
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

chowmillersumobots - 8 views

chowmillersumobots.wordpress.com

sensor NI sound iRobot sensors detection robot Ultrasonic wall obstacle

shared by Alexander Laferriere on 15 May 12 - No Cached
  • Declan Coen on 15 May 12
     
    the robot designs on this page are possible for our criteria. the majority of them have a ramp like structure on the front for pushing and flipping
  • ...3 more comments...
  • Joshua Wilkinson on 15 May 12
     
    the ramp on the front seems to be the easiest way to win based on other designs ive seen.
  • Alexander Laferriere on 17 May 12
     
    this has some good ideas
  • Thaddeus McKeon on 17 May 12
     
    the terminator looks like a fun approach to this project
  • Thomas Helm on 17 May 12
     
    i wish i could see some of the videos but i cant right now i wanted to see if thee were any changes to ramp in general
  • Jarid Brogan on 17 May 12
     
    the sumobotofdestruction looks cool and doable
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