Author Topic: Ultrasonic VS Sharp IR  (Read 2558 times)

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Offline RebelgiumTopic starter

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Ultrasonic VS Sharp IR
« on: September 04, 2007, 07:52:45 AM »
Ultrasonic is a bit more expensive, but is it worth it?

I want to use a 180? rotating servo with two Sharp IR sensors on top, and use this to navigate and later on even make maps.
What is best for this application? 2 ultrasonic sensors (= sonar?) or two IR sharps?

I know the range is better, but what about the speed? I want to ratate that servo asap, to have a higher map-refresh rate. Which is faster, IR or US?

Any other things I should know?
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Offline Steve Joblin

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Re: Ultrasonic VS Sharp IR
« Reply #1 on: September 04, 2007, 08:53:44 AM »
Different sensors are made for different conditions.  As you might imagine, IR sensors work faster than Ultrasonic sensors (light travels faster than sound).

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Re: Ultrasonic VS Sharp IR
« Reply #2 on: September 04, 2007, 09:31:17 AM »
Quote
As you might imagine, IR sensors work faster than Ultrasonic sensors (light travels faster than sound).
Although true, there is another bigger reason why IR is faster. US must have a significant time delay between bursts so that there is no 'noise' (literally sound noise) echoing from previous bursts.

Quote
use this to navigate and later on even make maps
For accurate map making, IR is by far best. For basic object avoidance, US is best :P

If you really really need speed, consider using multiple sharp IR simultaneously. Ive used up to 3 with good success.

Offline RebelgiumTopic starter

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Re: Ultrasonic VS Sharp IR
« Reply #3 on: September 04, 2007, 03:48:05 PM »
I am going to use 2 IR Sharp sensors on top of my rotating servo, This should give me 180? front view.

I'll use these to avoid objects and to make a map. For the object avoidance I'll also use basic IR proximity sensors.
Does this sound like a solid plan to you?

I want to buy this so I can start simple (2 IR Sharp sensor that don't move), and advance later on when I'm more experienced, without having to buy new stuff.
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Re: Ultrasonic VS Sharp IR
« Reply #4 on: September 04, 2007, 09:10:19 PM »
Sounds good to me. :)

For my 2 IR robot, the left sensor scanned 0 to -50 degrees, while the right sensor scanned 0 to +50 degrees. A full scan was about ~.8 seconds on an HS-311 servo.

In the future, if you want to get more complicated to increase speed and stay accurate . . . do slow high accuracy scan just in the direction of movement, then do a faster low accuracy scan on the sides . . .

Offline RebelgiumTopic starter

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Re: Ultrasonic VS Sharp IR
« Reply #5 on: September 05, 2007, 06:05:17 AM »
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In the future, if you want to get more complicated to increase speed and stay accurate . . . do slow high accuracy scan just in the direction of movement, then do a faster low accuracy scan on the sides . . .
Tnx for the tip, I'll keep it in mind.
To relax after some hard work on robotics: A very fun free online text based MMORPG
orgcrime.net

 


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