Author Topic: Sharp GP2Y0D340K sensors - strangely sensitive to noise  (Read 2812 times)

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Offline RiOTopic starter

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Sharp GP2Y0D340K sensors - strangely sensitive to noise
« on: March 13, 2009, 12:54:33 PM »
I use Sharp GP2Y0D340K (12 in digital) sensors for my sumo Robot.
They seem to be giving false positive readings from time to time, which disrupts my robot operation.
It only happens when my motors are running.
I use Maxons 13017 and Pololu TRex Jr controller (Freescale 33887 based). Could that be electrical noise? Is there a way to fix it easily? Please give me advice.
Specifically I am interested in what noise-protection people use with these sensors. ???

Offline pomprocker

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Re: Sharp GP2Y0D340K sensors - strangely sensitive to noise
« Reply #1 on: March 13, 2009, 12:56:58 PM »
these are very noisy sensors the solution is to put a capacitor on there somewhere...Search the forum.

Offline RiOTopic starter

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Re: Sharp GP2Y0D340K sensors - strangely sensitive to noise
« Reply #2 on: March 13, 2009, 01:09:49 PM »
I connected it exactly as in datasheet http://sharp-world.com/products/device/lineup/data/pdf/datasheet/gp2y0d340k_e.pdf
No I could not find anything about them in this forum. Maybe under different name?
Shall I attach a cap to the output leg? If yes - what size? Maybe RC filter?

Offline pomprocker

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Re: Sharp GP2Y0D340K sensors - strangely sensitive to noise
« Reply #3 on: March 13, 2009, 04:07:24 PM »
Here this link talks about adding a cap on the power/gnd and on the signal

http://www.robotroom.com/DistanceSensor3.html


Offline RiOTopic starter

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Re: Sharp GP2Y0D340K sensors - strangely sensitive to noise
« Reply #5 on: January 19, 2010, 07:24:15 AM »
I reviewed these links and added the capacitors, but still have noise issues.
Would anyone have a solution specific to GP2Y0D340K?

Offline waltr

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Re: Sharp GP2Y0D340K sensors - strangely sensitive to noise
« Reply #6 on: January 19, 2010, 08:34:42 AM »
Since you only experience a problem when the motors are running I suspect noise from the motors. Brushed DC motors are notorious for producing noise, brush contacts arc. So it would be best to kill the noise at the source.
Try putting a .001 uF ceramic disc cap on each motor terminal to the motor case.

Offline RiOTopic starter

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Re: Sharp GP2Y0D340K sensors - strangely sensitive to noise
« Reply #7 on: January 20, 2010, 01:55:26 AM »
waltr,
thank you for the suggestion, but I think that the motors can be ruled out. I tested the robot on a rack, with motors running, but wheels off the ground and had no single false positive  from the sensors.

Offline waltr

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Re: Sharp GP2Y0D340K sensors - strangely sensitive to noise
« Reply #8 on: January 20, 2010, 04:02:10 PM »
Did you have any problems with the robot on the ground so that the motors are loaded? This would increase the motor current and make brush noise worse.

You did say you only get false positive readings when the motors are running. Right?

How is the power connected to the motor driver and the processor? Each should go directly to the battery.

Offline Pratheek

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Re: Sharp GP2Y0D340K sensors - strangely sensitive to noise
« Reply #9 on: January 21, 2010, 09:10:35 AM »
I think your battery is not able to power both your processor and your motors. Try using a higher capacity battery (Li-ion or Li-poly) or uses two different batteries for your motor and your processor.

Offline Soeren

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Re: Sharp GP2Y0D340K sensors - strangely sensitive to noise
« Reply #10 on: January 21, 2010, 09:13:15 AM »
Hi,

Did you have any problems with the robot on the ground so that the motors are loaded? This would increase the motor current and make brush noise worse.
I have to second that!
3 caps directly on the motor (from each terminal to the motor housing which should be grounded as well and one 10nF+ from terminal to terminal).
And separate wiring to each motor and the logic of course.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline galannthegreat

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Re: Sharp GP2Y0D340K sensors - strangely sensitive to noise
« Reply #11 on: January 22, 2010, 12:18:01 PM »
I myself found that braiding the motor wires really helped aswell, it eliminated the noise issues on one of my 'bots.
Kurt

 


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