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Unread 12-12-2012, 03:06
RRLedford RRLedford is offline
FTC 3507 Robo Theosis -- FRC 3135
AKA: Dick Ledford
FRC #3135 (Robotic Colonels)
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Re: FTC 2012 RobotC IR Sensor Programming and implementation

This I/R detector makes no sense to me.

Issue #1 -What are the 9 "zones" and how does the 5-detector array define them. If the sensor "sees" 240 degrees, across five dector array zones, then is each detector handling 48 degrees of the the total 240 degree span, or do the individual detectors have wider overlapping views (maybe 60 degrees with 12 degree overlap?

Issue #2 - What causes the nine zones to have different "beam" arc widths (5 & 60 degree)? In fact why is the term "beam" even applied to the sensor, since the actual I/R energy beam is being sent from the beacon & no "beaming" should happen at the sensor? Is there some kind of prismatic beam focusing effect happening in the lens that slices up the incoming I/R energy such that it concentrates narrower slices (5 degrees worth of the 240 degree field) on the the radial midpoint axis between detectors, and it slices 60 degree slices of the 240 degrees of incoming I/R energy onto the radial central axis of each of the five detectors?

Issue #3 - If the sensor's central axis for zone 4 field view (located halfway between detectors 2&3 - with a 0-1-2-3-4 detector numbering scheme) is pointed straight ahead, and sensor is positioned at center of the bot, then when the data readout list indicates that the five detector array readings are coming from the zone 4 sector of the incoming I/R energy field (5 degree segment), then, when the bot is lined up centered in front of the beacon, shouldn't the detector array list of the five zone 4 direction array data values be showing that the highest number will be for the middle detector and the # values for the two adjacent I/R array detectors should be BOTH be somewhat less than the middle detector value, AND also nearly equal to each other?

Issue #4 - As the robot moves, what causes the I/R sensor to cycle through the zone numbers as it updates the data list with new values? Is it just that the sensor somehow determines that the peak energy is coming from that direction? How does the sensor ignore the incoming I/R energy from the other zones, and how does it decide which four to ignore?

I really don't understand how the sensor slices up the incoming 240 degree field of I/R energy into the 5 & 60 degree segments, and how the array knows what energy is hitting it from which slice of the 240 degree field?

Does the lens block incoming I/R energy from hitting the detector with some sort of staggered, variable angular width blinders that cast shadows on the detector, only allowing a certain sized (5 or 60 degrees) angular slice of the I/R energy reach the detector according to the directional line from the beacon to the sensor and the sensor pointing direction?

-Dick Ledford
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FTC 3507 RoboTheosis
FRC 3135 Robotic Colonels

Last edited by RRLedford : 12-12-2012 at 03:13.
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