DVL sensor crash on second simulation run

[youssefattia98]

I’ve been having an issue with the DVL sensor when restarting a simulation or re-running a ScriptNode that uses it. The first run works fine the DVL and its beams are created and return data but on the second or third run Isaac Sim throws repeated “Light Beam Sensor does not exist” and “Simulation view object is invalidated” errors, and eventually crashes.

It seems like the USD prims for the DVL stay in the scene between runs, but the underlying PhysX light beam sensor interface gets invalidated when the Python graph resets, so the sensor can’t reconnect.

`from isaacsim.oceansim.sensors.DVLsensor import DVLsensor
import omni.graph.core as og

def setup(db: og.Database):
db.internal_state.dvl = DVLsensor(name="DVL")
db.internal_state.dvl.attachDVL("/World/BlueROV2/base_link")
db.internal_state.dvl.add_debug_lines()

def compute(db: og.Database):
db.outputs.execOut = og.ExecutionAttributeState.ENABLED
db.outputs.vx, db.outputs.vy, db.outputs.vz = map(float, db.internal_state.dvl.get_linear_vel())
return True
`

Running this once works, but re-running it without clearing the scene crashes Isaac Sim. It seems like the DVLsensor class might need a safe way to rebind to existing prims. could you give me some guidance?

[haoyuma2002814]

Hi,

Thank you for using OceanSim.

Regarding the script you have attached, this is not a standard way for attaching sensors.

I notice you have db in your setup function, are you trying to use the sensor through action graph? If so, I recommend using the way in our example to setup the sensor.

We have not developed the OmniGraph version for our sensor. In your case the DVL object is trashed (probably) when you reload the scene if you are using OmniGraph workflow. I am not very sure internally why it crash the app, neither know why it can even work in the first run, but we recommend user using sensors following the examples we provided and our implementation is not designated for the OmniGraph flow.

If you are thinking about ROS and that was the reason for using OmniGraph, please take a look at ROS branch of this repo as there is example for publishing sensor readings to ROS.

Please let me know if you are still facing this issue and if I interpreted wrongly of your code.

Thank you.