How to get the precise distance to the front vehicle in the same lane?

[hjg857]

Hello, I am working on integrating a safety model (RSS) into an agent trained in MetaDrive. To calculate the required safe distance, I need to reliably obtain two key pieces of information in every step:

1.The distance from the ego vehicle to the closest front vehicle in the same lane.

2.The relative speed between the ego and that front vehicle.

[QuanyiLi]

Hi @hjg857,

The best way to do this is to first get all surrounding vehicles with the lidar.perceive see this file:

metadrive/metadrive/component/sensors/lidar.py

Line 48 in 85e5dad

def perceive(

It will return all surrounding objects. For a Vehicle instance, you can get its current lane by vehicle.navigation.current_lane. See here.

Note that it won't work if two lane segments are connected, which makes them visually the same lane, but vehicles are on different segments. So it would be better to include the next lane of the vehicle's current lane into consideration. Like what we have done for IDM policy here, which is able to find the front/back object on the same lane and the neighbor lanes.