# VOA with front and rear stereo pairs

Source: https://forum.modalai.com/topic/2002/voa-with-front-and-rear-stereo-pairs
Category: VOXL 2 and VOXL 2 Mini (https://forum.modalai.com/category/26/voxl-2-and-voxl-2-mini)
Tags: voxl-2
Posted: 2023-03-27 13:45:01 UTC by afdrus
Replies: 6 · Views: 1376

## afdrus · 2023-03-27 13:45:01 UTC

Hi everyone,

I am setting up a drone with VOXL2 to perform obstacle avoidance using both front and rear stereo inputs. So far, everything seems to work reasonably for the front camera pairs, but as for obstacle distance readings from the rear stereo, an obstacle seem to be always present in the back of the drone. I think that the reason behind this detection is related to my current design of the drone which partially occludes the FOVs of the stereo pair (see pictures below). Could you confirm if this could be the issue? Is there a parameter in the config files that could allow me to discard point clouds that are too close (i.e. in my case the chassis of the drone)?

Thanks a lot in advance for your reply!
[![Screenshot-from-2023-03-27-15-34-43.png](https://i.postimg.cc/bJqqnBH9/Screenshot-from-2023-03-27-15-34-43.png)](https://postimg.cc/bGFXcL5Z)

## Reply by bensusana · 2023-07-26 09:44:28 UTC

hi @afdrus afdrus
can you share how did you enable voa on voxl2 platform?
i didn't fund  much details :)

## Reply by afdrus · 2023-07-27 08:22:41 UTC (in reply to bensusana)

Hi @bensusana !

It depends which SDK you are using, if you are using SDK 0.9.5 you have to setup the parameters in voxl-vision-px4. There you can both enable the VOA (```
en_voa: true
```) and select the camera with which you want to perform the VOA ```
voa_inputs
```. Then, if you want to send the VOA data with the telemetry to the ground station you can also set ```
en_send_voa_to_qgc: true
```

## Reply by bensusana · 2023-08-03 07:43:45 UTC (in reply to afdrus)

@afdrus 
thank you !

## Reply by Jetson Nano · 2023-11-17 06:54:05 UTC

Hey @afdrus , I am trying to do VOA with VOXL 2 and SDK 0.9, I am getting correct obstacle distances, but the drone is not stopping at the distance, not doing collision prevention

## Reply by afdrus · 2023-11-17 08:56:22 UTC (in reply to Jetson Nano)

@Jetson-Nano You should also change some parameters on the autopilot's side, did you do that? Which autopilot are you using?

## Reply by Jetson Nano · 2023-11-17 10:01:47 UTC (in reply to afdrus)

@afdrus Those CP parameters right, I did it. I am using PX4 1.12