Hardware：pixhawk 2.4.8
Firmware：ardurover 4.3
Radar：rplidar S2M1
The connection with cartograph_ros and mavros has now been successfully established. And the direction of pixhawk is consistent with the direction of rplidar. When I control the rover to move forward, the GCS shows that the vehicle is moving in the opposite direction. At the same time, obstacles are also displayed behind the vehicle.
Then I opened rviz, and the direction of the arrow displayed by tf was exactly the same as the direction of the radar.
Have you tried to rotate the lidar 180deg?