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Author Topic: $50 with IR problem  (Read 2148 times)

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Offline ConscriptedTopic starter

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$50 with IR problem
« on: June 27, 2009, 11:22:44 PM »
Ok so I tried to finish the sharp IR upgrade for the $50 dollar bot. It didn't go as I expected. The scanning servo locks out to the left and the bot goes in circles. Occasionally one or two of it's circles turns into an ellipse and it will move a little but it isn't in response to any stimulus that I can see. I tried playing with the value for MAX scan angle but that just made the servo jitter.

How can I verify that my sharp sensor is working?
I'm a little disappointed right now. I was hoping to have this working tonight.

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PS here is a pic.

Offline Metal Slug 2

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Re: $50 with IR problem
« Reply #1 on: June 28, 2009, 12:57:34 AM »
did you make sure that when you turned your robot on you "calibrated" it? (a task you must perform every time you turn your robot on).  Calibrating the IR rangefinder basically manually lets you set the distance in which the robot is intended to follow objects at.  to calibrate, simply hold an object at your desired distance  from the IR rangefinder and turn on your robot, wait a coule seconds and you should be set.

Offline ConscriptedTopic starter

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Re: $50 with IR problem
« Reply #2 on: June 28, 2009, 07:39:38 AM »
Yeah, I tried to do the calibration. It doesn't seem to affect the behavior at all. I tried holding several different objects. I also tried putting it in front of a wall.

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Offline kpmcgurk

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Re: $50 with IR problem
« Reply #3 on: June 28, 2009, 04:22:11 PM »
make sure that your servos/IR sensor is plugged into the right headers. for some reason the scanner servo is in the middle of the other two servos. and then the IR scanner is plugged into 2 headers from the edge of the micro (pin 26)

In addition make sure that the wire from micro to sharp IR is good (ie. no shorts and/or resistance)
 
Finally... Just troubleshoot it. You will need to play around with different callibration distances and stuff to get what works great for you!

good luck
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Offline Miles

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Re: $50 with IR problem
« Reply #4 on: June 28, 2009, 05:45:40 PM »
Make sure you have wired up the IR sensor correctly, in terms of Positive, Negative and signal. I noticed your wire connector at the MCU board, the colour arrangement is not the typical arrangement (red is usually in the middle for positive). Also there is a post in the forum somewhere that shows a picture of the connection at the IR which you might want to double check.

Offline ConscriptedTopic starter

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Re: $50 with IR problem
« Reply #5 on: June 28, 2009, 08:26:54 PM »
Thanks for the responses.

Make sure you have wired up the IR sensor correctly, in terms of Positive, Negative and signal. I noticed your wire connector at the MCU board, the colour arrangement is not the typical arrangement (red is usually in the middle for positive). Also there is a post in the forum somewhere that shows a picture of the connection at the IR which you might want to double check.

The wires are atypical because I used a connector that fit from my scrounge box. I looked through a couple of posts that verified the wire colors. Admin posted a good one a couple of years ago that i found. I'll double check the placement of my scan servo.

If I plug in power and ground to 5V can I measure the signal line with a multimeter to verify it's working properly?

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Offline SmAsH

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Re: $50 with IR problem
« Reply #6 on: June 29, 2009, 12:50:35 AM »
with a multimeter, it will be hard.
this kind of thing is better suited to an o-scope...
although you can try moving things closer and see how the voltage changes...
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Offline sirius86

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Re: $50 with IR problem
« Reply #7 on: June 29, 2009, 01:23:18 AM »
Quote
for some reason the scanner servo is in the middle of the other two servos. and then the IR scanner is plugged into 2 headers from the edge of the micro (pin 26)

well the video of mounting the IR rangefinder shows tht the scanner servo is connected in 3rd o/p port after the 2 wheel servos (counting from the black capacitor side), so now im also confused! plus which is the actual port to connect the rangefinder to the circuit???

Offline Miles

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Re: $50 with IR problem
« Reply #8 on: June 29, 2009, 01:29:58 AM »

If I plug in power and ground to 5V can I measure the signal line with a multimeter to verify it's working properly?
[/quote]

*YES* you can. Connect the IR rangefinder to positive 5V and negative 0V. Then get your multimeter and put the Red probe on the signal line of the IR rangefinder and the Black probe to the 0V on the IR rangefinder. Then you will be able to measure the signal voltage which is what the MCU reads. This will also help you determin the max range that it can see at.
« Last Edit: June 29, 2009, 01:31:54 AM by Miles »

Offline ConscriptedTopic starter

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Re: $50 with IR problem
« Reply #9 on: June 29, 2009, 06:26:03 AM »
Thanks Miles! That was exactly what I had in mind. I'll let everyone know what the results are.

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Offline sirius86

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Re: $50 with IR problem
« Reply #10 on: July 07, 2009, 02:58:41 AM »
hey...were u able to solve ur IR problem in the end??? im still stuck with it! i didnt hav the chassis till now...but finally made one and tried but the same problem exist... :(

cud it be tht im using only one 6V (which gets regulated to 5V) battery to run the whole circuit including 3 servos??? coz wen i charged the battery for a couple of hours, on the first try, it seemed to work to some extent...cud using the 9V and 4.8V batteries together help me??? plz lemme know anyone...

thnx...

Offline SmAsH

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Re: $50 with IR problem
« Reply #11 on: July 07, 2009, 03:24:02 AM »
well, your problem may be with the 6v... the regulator requires a bit over 6v to run...
try using a 7V2 pack to run the whole thing... or 9v+6v...
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Offline sirius86

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Re: $50 with IR problem
« Reply #12 on: July 07, 2009, 04:54:29 AM »
thnx smash...

i dont hav the 4.8V battery holder...i hav the 9V and 6V...can i use them in the way given in the step 3B of the tutorial for 9V and 4.8V batteries???

thnx again...

Offline SmAsH

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Re: $50 with IR problem
« Reply #13 on: July 07, 2009, 05:28:37 AM »
yeap, the 6v and 9v will work the same as the 4V8 and 9v.
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Offline ConscriptedTopic starter

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Re: $50 with IR problem
« Reply #14 on: July 07, 2009, 06:25:25 AM »
I haven't fixed my bot yet. I haven't had time to work on it. Any luck with yours sirius86?

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Offline sirius86

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Re: $50 with IR problem
« Reply #15 on: July 07, 2009, 01:20:58 PM »
nope...no luck yet... :( i made the chassis, but still the same results, just as i connect the 6V battery to the header, the IR servo givs one jerk to one side n gets stuck...n the robot keeps moving in circles!  >:( i think it gave slightly different reactions wen i had tried after charging the battery for a couple of hours, so i think maybe the single 6V may not be enuf to run the whole thing...will try using both my 6V n 9V together n see the results...wat batteries did u use conscripted???

Offline ConscriptedTopic starter

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Re: $50 with IR problem
« Reply #16 on: July 07, 2009, 05:16:49 PM »
I used a rechargeable 9v battery to run the MCU. It goes through the 5v regulator. I used 4x aa batteries for the servos.

 


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