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IR-Ranger Board

by Sébastien Lelong last modified 2007-03-18 12:11

GP2D02 based

Author: Sébastien Lelong, The SirBot Project, 2006
Revision History
Revision: 409 Initial creation
$Revision: 441 $ Convert into REST
Abtract

The IR-Ranger Board, connected to the Main Boad, provides a way of measuring distances, with the GP2D02 IR ranger.

Electronic diagram

The IR-Ranger board doesn't contain lots of components, as shown in the following diagram (only a diode):

irrangerboard_schema.jpg

Electronic assembly

The following pictures show the implementation of the components on a board:

irrangerboard_front.jpg

Reverse side:

irrangerboard_reverse.jpg

Calibration

The GP2D02 IR ranger output its distance measures as a byte. After enabling the ranger, the GP2D02 gives its result as a sequence of 8-bits:

GP2D02_timing_chart.png

The following chart shows how to convert this byte into a cm distance:

GP2D02_measured_vs_real.png

The distance accuracy depends on the reflective object material, and other stuffs... Let's say the distance is reliable between 10cm (byte with decimal value ~200) and 80cm (byte with decimal value ~75).

In order the robot to provide distances, we have to found the approx. formula of this chart. Taking points on the chart, putting the whole into Excel, gives the following chart:

GP2D02_plot.png

Now we have the formula: f(x) = (760893/x)^(1/2.1286). The robot will be able to easily convert its received bytes into human readable distances...


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