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Number Of IR's Needed For Boe Bot To roam the house. — Parallax Forums

Number Of IR's Needed For Boe Bot To roam the house.

don_sdon_s Posts: 35
edited 2006-02-23 00:43 in Robotics
Trying to get my Boe-Bot to roam the house. I recently had two (2) IR's pointed in the front @ 45deg of each other. Was not able to see the walls as the bot angled in and had a dead zone in front were the eyes would not see the object at all. Now have the two(2) IR's pointed Straight ahead and about 1" space between them. This is a little better but I still have a problem with walls on the side and directly in front.
To make a long story short, trying to determine what I need and I come up with six(6) IR's. Four in front (Left Front, Right Front, Front for Height, Front For Drop-off's, and one on each side). I also think that this might be overkill.


So, help. Is there a more effiecent way to use the IR's to allow using less, or to adaquatly allow the Bot to see, I will need this many IR's (or possibly more)!


Thanks
Don "Ho"

Comments

  • Steve JoblinSteve Joblin Posts: 784
    edited 2006-01-18 18:37
    I have had much success with just two IR's as described in the Robotics! Stamps class... try mounting them on each side of the front of your robot facing forward... then spread them apart angling outwards to the sides a bit... if you still hit walls, try spreading them a bit more... lots of trial and error here, but you will eventually find a "sweet spot" that will capture obstacles in front as well as to the sides. I think you might have been a bit over zealous in separating them 45deg of each other, try a smaller angle.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-01-18 20:28
    Steve has the right idea.· Sometimes it's trial and error.· You need to use the IR Test program to help you adjust the IR sensors by moving them and waving something (Like your hand) in the areas of detection to get them to a nice happy medium where they see sufficiently on both sides and in front.· The side view will be limited while allowing full frontal sensing, but enough to keep the BOE-Bot from coming into the wall at a wide angle.

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • don_sdon_s Posts: 35
    edited 2006-01-18 21:24
    So you are saying to angle them out. I was placing them in to overlap the coverage in the front. If you angle them out, wont you get a dead spot in front? I will give this a try tonight.

    Thanks
    Don "Ho"
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-01-19 02:55
    Yes, if angled out you will get a dead spot.· That's not what I said.· You need to moved them until you minimize the dead spot while getting some side coverage (More like 45 degrees off to the side).

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2006-01-21 16:44
    Seems to me that you could do better with bumpers, sonar and IR.
    IR is well known for not seeing black objects.

    The sonar might sense a general path and the IR might navigate obstacles closer at hand.

    Finally, you should have 'whiskers' or 'bumpers' as tactile collision is a very real part of navigation that takes place when all else fails [noparse][[/noparse]just look at any pub at closing time to see what I mean].

    Also, if you really want it to roam the house, you might consider a couple of drop-off IR sensors that are pointed straight down. That way it won't wander down a stairwell.

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    "When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

    ······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-01-21 18:45
    Kramer,

    ·· Actually a combination of sensors would be the "best" approach since that would compensate for shortcomings of other sensors.· Even sonar isn't perfect.· Uneven or angular surafces will not reflect sound well.

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • don_sdon_s Posts: 35
    edited 2006-01-25 20:19
    Adding more sensors was in my design. Before I went to another type, I felt it would be best if I could at least get the ones that I have working correctly and understand how they are working. I was trying to eliminating the "Wiskers", but you are correct, I am not able to program for all possible close encounters.

    I am now thinking of 4 IR in the front, with one pointing downward, 1 on each side. One Sonar mounted on a servo. And I guess now, wiskers.

    This will take more pins that one stamp will have, so I will need to figure out how to make two stamps talk to each other. Should I continue to use the Boe-bot chassis to do this, or should I just bite the bullet and bulid one from the ground up..

    Decsions, Decsions, Decsions..
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-01-25 21:36
    Don,

    ·· Not necessarily...I went through this once too trying to overload my first BOE-Bot to cover everything...Of course there was no PING))) then so I lost two pins to Sonar.· In any event I later decided to look at websites that showcase various bots, especially those used in competitions.· My research showed that will a little forethought and ingenuity you can come up with a simple, yet powerful sensor array.· Many of the bots I discovered that were simpler won more competitions because their controllers had less work to do monitoring many unused sensors while being able to focus more on a way of dealing with the data they did have.· Just a thought.

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • LejgeoLejgeo Posts: 8
    edited 2006-01-25 22:37
    why not add a photocell ciruict? for example

    High 6
    pause 3
    rctime 6, 1, photocellL

    if ( photocellL > 100) then
    gosub forward



    something like that... [noparse]:)[/noparse]
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2006-01-30 06:48
    There is a definite synergy of using combined sensor technologies.
    Many of the Parallax customers are beginners, so the books focus on introducing 'one thing at a time'.

    But, if you want a robot to survive, it likely needs something akin to our 'five senses'.
    We truly rely on all to navigate and protect us.

    While you can obviously consider eliminating taste and smell, you might add something akin to balance.

    There are also different degrees of importance based on how far away the information comes from.
    That is why bumpers are quite important.

    When all else fails, stubbing your toe or bumping your arm tells to revise your navigation.

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    "When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

    ······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
  • don_sdon_s Posts: 35
    edited 2006-02-22 15:53
    Thanks for all the information. I broke down and now have one Ping))) and two Sharp Sensors. Finished up the programming last night and put the bot down and turn her lose. For the next hour, I was watching the bot move about the house without hitting a thing. Finally sucess!!!

    Been so long trying to get this done, I dont know what is next. I do have the Wheel watchers and the bot does not go straight, so I need to research this more to make this work.

    Another question is how much can I put on before I see a voltage drop?
  • Robert25Robert25 Posts: 53
    edited 2006-02-23 00:43
    Just a quick note. I eliminated my whiskers and gained two pins. However, for navagation, I mounted a Ping sensor to a servo that "looks" around while roaming. I haven't hit anything and I do not have IR (yet). In fact, I added the EMIC module and the bot says things when roaming like "Uh oh, there is something in my way." etc....
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