IWR6843ISK: Where is the origin defined on the sensor to estimate the position of detected point cloud

Hi Kai,

The Point cloud is in reference to Antennas on the sensor.

Thanks

Yogesh

Hi Yogesh

Thanks for your quick reply.

I understand that the point cloud is defined with respect to antennas. Since the point cloud always has a coordinate of (x0,y0,z0), there must be a origin point. My question is that where is (0,0,0) defined.

Thanks!

Kai

Kai,

Roughly it is b'n rx antennas for far object. 

Is your object near and are you trying to apply near field  correction as mentioned in the attached guide?

Thanks

Yogesh

user_guide.pdf

Hi Yogesh

What did you mean b'n rx antennas? I am trying to estimate the global position of objects accurately. That is why I need to know the reference origin defined with respect to the sensor.

Thanks!

Kai

Hi Kai,

You will need to do calibration for getting the accurate origin.

For course reference you can use center of the RX Antenna of the attached IWR6843ISK image.

Thanks

Yogesh

Hi Yogesh

I believe the calibration only helps get accurate position with respect to the sensor but has no impact on the origin.

From this image, the center of RX antennas only gives me the origin in the azimuth. How about the origin in the elevation?

Thanks!

Kai

Hi Kai,

Not sure if I understand, the accurate position with respect to sensor is origin itself. Am I missing anything here.

Thanks

Yogesh

HI Yogesh

The position of a target reported from the sensor is the relative coordinates defined in terms of sensor origin. The calibration procedure is able to provide accurate position with respect to sensor origin. But I still have no idea on where the origin is because what I am interested in is the global position of a target rather than the position with respect to the sensor origin. That is why I need to know where the origin is defined exactly. Hope this makes sense to you.

Thanks!

Kai

The exact origin is not defined. This is because of the far field assumption in the angle calculation.

Hi Piyush

In this case, is there a way to find the global position of a target from the relative position with respect to the sensor?

Thanks!

Kai

Hi Piyush

By global position, I meant it is position defined with respect to somewhere else, e.g., one corner of the room, rather than the sensor. In this case, the global position is equal to the sum of the relative position vector + sensor origin vector. From your answer, it seems the global position I get will have the maximum error around the physical dimension of the antenna array since the exact origin on the sensor is not well defined. Am I correct?

Thanks!

Kai

correct