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Ultrasound vs. IR sensors
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Ultrasound vs. IR sensors

by project_science on Wed Apr 19, 2017 6:36 pm

Hi,

I need to make a project which uses a detection trigger system, using either ultrasound or IR sensors. The system needs to run 5 sensors, each spaced 4 ft apart on a line.
I have two choices:

5x Sonar: https://www.adafruit.com/product/982

OR…

5x IR: https://www.adafruit.com/product/1031

Question: Which has a narrower beam width (less interference with other of the same sensors in the area): the sonar (ID: 982) or the IR sensor (ID: 1031)?

Thanks!

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Re: Ultrasound vs. IR sensors

by adafruit_support_rick on Wed Apr 19, 2017 7:27 pm

The sonar will interfere with each other. The IR sensors are what you want. If you do encounter interference you can put a baffle on the receiver to block out adjacent light sources.

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Re: Ultrasound vs. IR sensors

by adafruit_support_bill on Wed Apr 19, 2017 7:32 pm

Actually, the Maxbotix sensors can be wired to synchronize with each other to avoid interference. See page 5 of the data sheet: http://www.maxbotix.com/documents/HRLV- ... asheet.pdf

I've done this using sensors with intentionally crossed beam patterns for triangulation on a target and it works quite well.

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Re: Ultrasound vs. IR sensors

by project_science on Thu Apr 20, 2017 4:11 pm

I think I should have added, that the sensors will be run from different microcontrollers - 3 to be exact. Two of the UNOs will run two sensors, and then 1 UNO will only run one. I have reasons for this.

Given this situation, that's why I'm asking which has minimal change of interference. I'll be using a target detection range of 1-3 or 1-4 feet.

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Re: Ultrasound vs. IR sensors

by adafruit_support_bill on Thu Apr 20, 2017 4:19 pm

The Maxbotix sensor synchronization is independent of the microcontroller. You could wire a whole array of synchronized sensors and monitor their outputs with separate controllers.

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Re: Ultrasound vs. IR sensors

by project_science on Wed May 31, 2017 3:38 pm

I'm looking to wire 5 of these together: https://www.adafruit.com/product/982

How long does it take the chain of 5 to loop?

And is there any extra code I have to write into my sketch on each of the UNOs to accommodate the chain? (5 sensors, with only 1 wired to each of 5 microcomputers)

All I'm really trying to do here is prevent crosstalk, and if one of the sensors' thresholds are matches, then to light an led on the microcontroller which the sensor is attached to.

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Re: Ultrasound vs. IR sensors

by adafruit_support_bill on Wed May 31, 2017 4:00 pm

It takes 50ms for each sensor to cycle, so a chain of 5 would take 250ms in total.

There are a couple ways to do it. If you have an open ended chain, you will need to pulse the first sensor in the chain to start a read cycle.

If you connect them in a loop for continuous reads, you just need to pulse one of the sensors at startup and they will continue to cycle indefinitely.

With the continuous reads configuration, you can read the analog outputs at any time. There is no need to synchronize your processors.

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Please be positive and constructive with your questions and comments.