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[ALMemory] Explaination of laser sensory Key-Names


im currently using ALMemory for get values from laser sensors.

The Keys of surrounding sensor are not clear to me.

They are like for instant...

What are they mean? UncertainObstacle? AnnoyingReflection?

Thank you.

Last seen: 3 months 2 weeks ago
Joined: March 30, 2017

Hey DonnyLe,

you're in luck, i just found out a little bit myself yesterday, may update more further because i'm working on identification of these right now.

Half of the things i've found it was based on my measurements, the other half of:

Small sketch showing the basic principle:

1. "Horizontal obstacle data" means we have a horizontal sweep by a single laser, we have three of those: Front, Left and Right.
2. X means the distance thowards the Pepper, the coordinates are polar coordinates, minimum Value is something like 30 cm, maximum is like 7m, you should generally not trust those values when you receive these. (For instance only use 40cm < x < 6.8m, i assume aldebaran did the same.)
3. Y means the distance the object moved rectangular to the X-Position of the object. Seems to work, but in my opinion not that useful.
4. There are segments, those are (probably) equally spaced across the 60° per sensor - which means 4° difference per value.

And the remaining things are just guesses:

"Vertical obstacle data" probably gives certain height values.

"Uncertain obstacle data" probably means there's a high variation in distance in in a few measurements, those could either be considered measurement errors, or parts which might need closer inspection. I think those parts are displayed in light grey.

"Annoying reflextion data" probably means a reflection was detected and the measurement has to be discarted as reflections produce measurements of way too high distances.

I didn't figure out the shovel lasers yet, i think they're for ground inspection, and they have to be turned on. The laser operation mode Sensor has a default value of 3, which means they're turned off (see end of Actuators and Sensors list) and i didn't figure out how to turn it on yet. Tried it with the insertData(Key, value) function, but it didn't work.

Bernd Griller

Last seen: 3 months 2 weeks ago
Joined: March 30, 2017

I'll have to clarify something about the segments: While the maximum angle difference is correct (60°) there are only 15 values to read, that being said the middle points of the measurements in degrees per Value would start at 2°:
2°+-2° = seg1, 6°+-2°=seg2, 10°+-2°=seg3 and so on. The usually most interesting value is segment 8 which is measurement in the middle.

Last seen: 1 month 2 weeks ago
Joined: May 2, 2017

Hi Bernd,

thx for sharing.

Shouldn't there be Keys for vertical Segments too? in

Last seen: 3 months 2 weeks ago
Joined: March 30, 2017

I don't think the focus of those lasers is the vertical sweeping, but they aperrently do have some values like:
(Was right there in the Actuator & Sensor List - Point B and C.)
Intrestingly those values cannot be received from the left and right laser.
The X-Value is of course the same as from the Horizontal sweep, but the Y-Value might make some sense to look into in order to avoid obstacles that are higher than laser sensor level - for instance tables.
Not sure how high (in vertical degrees) those measurements go.

Last seen: 1 month 2 weeks ago
Joined: May 2, 2017

Aren't they value for shovel sensory?

it's still mystery to me too, how high those mesurements go, according to document 40 degree, but in just one segment both for left and right.