Distance / Range finder

Comments

• Steve Joblin Posts: 784

  2005-11-15 22:25 edited 2005-11-15 22:25

  Very interesting issue... I have wondered this myself....
  
  I read a "white paper" that a High School student did comparing and contrasting accuracy of sonar vs IR.· Here is the link --> http://www.elqc.com/will/willg7sf.pdf
  
  Look at page 32 for the conclusion.
• Splynter Posts: 8

  2005-11-16 15:43 edited 2005-11-16 15:43

  Wow, thanks Steve.· That is just what I was looking for.· Seems like the Ping))) is much more accurate.· Do you know if the power consumption is relatively the same?· Also as I understand the DIRRS+ has a narrower beam than the Ping))) which means it will see things the are directly in front of it where as the Ping))) will also see things that are off to the side, is this correct?· What I'm getting at is if I use the Ping))) as object detection/avoidance for my bot, it will see and avoid things that are not really in it's path (and that it really doesn't need to avoid).
  
  Thanks again for your help.
• IRobot2 Posts: 164

  2005-11-17 20:45 edited 2005-11-17 20:45

  One thing to remember is that the Ping))) sonar sensor is going to cone out from its point of origin. I have not really looked at any detailed info on them but I know for a fact that it is going to have a narrower detection field at 1ft than it is at 6ft. It is going to continue to cone outward till it reaches the point that sound can no longer be reflected back and be detected.
  
  When comparing any sonar to any IR sensor you have to look at the application that you are using them for. For instance Sonar would probably not be your best best for detecting objects really close to your robot where as IR could. If it is an outside robot, you have tons of IR interference such as the sun. I am sure that some IR sensors are more apt to work differently than others but is still something to consider. Even sonar has a blind spot. If you are looking at rounded objects, the sound signal that is produced by the sensor might reflect off in a different direction and not make it back to your robot to report that there is an obstacle in the way.
  
  These are just some things to consider.
  
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  Alex Burke
  burke@ajbrobotics.com
  
  
  
  "The factory of the future will have only two employees, a man and a dog. The man will be there to feed the dog. The dog will be there to keep the man from touching the equipment." ~Warren G. Bennis!
• Splynter Posts: 8

  2005-11-23 17:44 edited 2005-11-23 17:44

  Thanks for the input.· So if I understand correctly, if the Ping))) reports an object that is close (<2ft) then I can assume it is in the path (directly in front) of the robot, if it is further then it may or may not be in the path.· This is ok for me since I want to avoid objects that arre relatively close and in the path of the robot.·