Best Of

Thank you for both of your answers, but I am a bit confused now.

 

So according to your answer reinerh, the results also differ, if I use the RCS of the same CAD model in WinProp and also use ray tracing in WinProp compared to use the CAD model in WinProp with ray tracing directly?

 

But then the RCS should also not be used for projects in which multipaths occur and therefore the path is not reflected back in the exact opposite direction, do I understand that correctly? 

I have drawn a simple example (see attachments):

So the car has a monostatic radar at the front bumper and is imported via the normal CAD model in WinProp. Also the house is imported via a normal CAD model. For the truck I used the RCS calculated in Feko. 

The blue path from the car to the truck and back should be correct when using the RCS with the truck, but the orange multipath to the truck and the house back to the car will then deliver a wrong result, isn't it?

But then you couldn't use the RCS in Winprop for any project with multipaths, i.e. with more than two objects?

 

Thank you very much and best regards!

Hi,

by using the monostatic RCS imported in WinProp you get basically the directly back-scattered rays from the object to the sensor (Tx/Rx), plus there could be also rays having a single interaction (e.g. ground reflection) before and after the RCS interaction, because of the angular condition for the monostatic RCS it will exactly the same interaction point before and after the RCS interaction point.

Rays like the orange one as shown in your picture (sensor => RCS => building => sensor) will be not computed, because of the angular condition for the monostatic RCS, here you would need the bistatic RCS. However there might be rays like sensor => building => RCS => building => sensor computed, even with the monostatic RCS.

Overall the results might differ, if using the RCS as computed in Feko and using the same CAD model in WinProp with ray tracing directly, because of the different solvers implemented in Feko and WinProp.

Best regards,
Reiner

Hello @Lương Ngọc Lâm ,

this should be possible, but it is not part of the workflow in the exoskeleton context. The exoskeleton context will set up a model to perform either topology OR size. It doesn’t apply the size variables to a pre-run topology result (hopefully that makes sense).

This could be scripted, or, you could simply take the result from the topology and use those local regions to create new CBEAM’s and then perform size.

For such an approach, we would create size variables around the whole model and then delete the large majority we don’t want leaving only the isolated results as per image #4 in your message – that would be the quickest way but maybe not be the most accurate if you want the exact same position of the topology CBEAM and size CBEAM.

Hope this helps,

Michael

Hi,
when using the monostatic RCS in WinProp there is a check if the direction of the back-scattered ray is inverse to the direction of the incident ray, because the monostatic RCS is only valid for this case, which is then useful for radar sensors where Tx and Rx are at the same position.
There would be no such check when using a bistatic RCS, but so far the usage of bistatic RCS is not supported in WinProp

Computing the RCS in Feko applies different solvers compared to using the same CAD model in WinProp and applying the ray tracing model. From this perspective there can be some differences expected which depend on the specific object.

Best regards,
Reiner

Hi Adam,

Thank a lot for detailed explanation. 

Have tried as you explained but values of reaction are on higher side. 

Is this because of version difference? 

 

Would like to ask another question in case you can explain this. In same model if we remove spring and damper from front and rear both places then also total reaction at jack should match the total mass in log file, correct? But after removing spring and damper, total reaction forces around 500N only! Or I missed something here. 

Once again thanks for your time.

Hi Savan,

Based on your results, it looks like you may have skipped step 1 in my previous post. You need to change the Vehicle Restraint from Soft to None. I ran the event with the Soft restraint on just now and it produces the same results you are currently displaying.

This will also significantly impact the model with no springs and dampers, as you have pointed out, as you are essentially holding the bike in the air with the soft restraint and there is very little ground reaction occurring.

Hope this helps!

Adam Reid