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 Robotics / NXT / 929
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Subject: 
Re: Ultrasonic Sensor iS "Slow"
Newsgroups: 
lugnet.robotics.nxt
Date: 
Tue, 11 Sep 2007 04:17:39 GMT
Viewed: 
22270 times
  
John Hansen wrote on September 05, 2007 3:40 PM

The errors that occur are that the sensor does not properly report
variable distances as it is positioned at varying distances from an
obstacle.  If you slow down the read rate then it works correctly
(i.e., with a wait of ~15 ms between read transactions) but without
that delay it does not accurately reflect the varying distances as
it should.  I'm not talking about getting bus errors - just invalid
distance readings from the sensor.

You're right!! If you poll the sensor too fast, it definitely reports
wrong distances. I'm doing some more testing to characterize the error
performance.

The 15 ms that John reported is the time it takes for a sound pulse to travel
500 mm, the round trip distance at the maximum advertised range of the US
sensor.
An interesting coincidence?
Roger Glassey



Message is in Reply To:
  Ultrasonic Sensor iS "Slow"
 
Original Thread title was "Re: Ooops! NXT Software Comparison correction / I2C Messaging Speed". I've renamed as worth a separate thread. (...) You're right!! If you poll the sensor too fast, it definitely reports wrong distances. I'm doing some (...) (17 years ago, 7-Sep-07, to lugnet.robotics.nxt)

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