Time of Flight >>> Rounded Corners !!!

I placed the Sensor rig into a cardboard box just to get a feeling for the data.

This is two passes of the probe, so you can see the slight variance in data.

Overlaying the raw data for 180°.... this was with GIMP so its just approximate

all looks kinda good except Hmmmm.... rounded corners cannot be explained...

another scan with DVD's :-


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Mats's picture

FOV

The problem with the rounded corners probably is becuse the sensor sends light at a 35 degree angle and reads the reflection at a 25 degree angle. So narrowing down what it sees should probably improve the results. 

https://www.st.com/resource/en/application_note/dm00326504.pdf

https://www.st.com/resource/en/user_manual/dm00279088.pdf

 

Gareth's picture

Sharp corners - FOV reflections

Thanks mats for the impulse and the pdf's,

Wish I could see the reflected IR laser (at least seeing where it hits the object , the emitted IR laser is quite strong using mobile phone camera.

pdf's :- .. there are quite a few factors which could be the culprit, maybe reflections and the FOV constraints are getting confused.

One thing I need to try > My sensors are mounted vertically, I will have to try mounting horizontally

Ray.Edgley's picture

Amount of signal return

Hello Gareth,

It occurs to me the curving your seeing in the test data above may be a result of the amount of signal strength.

The sensor send out the IR signal as a cone and also receives back the signal using a cone.

As your sensor is being turned, the amount of signal being returned to the sensor within it cone will  increase as the closer object is being scanned onto. 
There is also the signal from behind the object as well.
It occurs to me that as the two signal pulses change it strength from the distant pulse to the near pulse, the sensor may be averaging the two signals to return the detected signal.

This theory would account for the rounding of your map around hard edged objects such as DVD cases.