# Collision Prevention doesn't work

Source: https://forum.modalai.com/topic/3993/collision-prevention-doesn-t-work
Category: Development Drones (https://forum.modalai.com/category/44/development-drones)
Tags: sentinel
Posted: 2024-12-03 19:15:06 UTC by Jerry Lin
Replies: 0 · Views: 650

## Jerry Lin · 2024-12-03 19:15:06 UTC

Hi, our team followed the [VOA instructions](https://docs.modalai.com/voxl-vision-px4-collision-prevention-0_9/) to try the important features needed in our projects and it appears "Collision Prevention" doesn't work like the video demonstrated and we still can get our Sentinel very close (around 2 inches) to walls or trees. The only thing possibly wrong is we don't get OBSTACLE_DISTANCE message in QGC. Otherwise, we can see all `stereo_front_pc`, `stereo_rear_pc` and `voa_pc_out` point clouds in *voxl-portal* with *voxl-dfs-server* running, *Health Check* and *voxl system check* in *voxl-portal* all passed and object detection enabled for different *Minimum Distance*s.![Screenshot 2024-12-03 at 2.01.13 PM.png](https://forum.modalai.com/assets/uploads/files/1733252479139-screenshot-2024-12-03-at-2.01.13-pm.png) and  CP_* parameters verified![Screenshot 2024-12-03 at 2.06.31 PM.png](https://forum.modalai.com/assets/uploads/files/1733252795940-screenshot-2024-12-03-at-2.06.31-pm.png):

Any clue how to debug?