Lidar message structure seems wrong in Unreal Engine 4 simulation (with carter_sim)

Hello everyone

I used the carter_sim application in the Unreal Engine 4 simulation
and i get
errors: the structure of the Lidar message seems to be incorrect
The Carter Sim application connects to Isaac Sim via TCP and instantiates the robot with multiple sensors in the simulator, in particular a lidar sensor.

This is what I did:
Instantiate the robot with its sensors with the following command:
bazel run //apps/carter/carter_sim:carter_sim – --config=“apps/assets/maps/carter_warehouse_p.config.json” --graph=“apps/assets/maps/carter_warehouse_p.graph.json”

I launch Isaac Sim Editor with the command:
./Engine/Binaries/Linux/UE4Editor IsaacSimProject CarterWarehouse_P -vulkan -isaac_sim_config_json="/home/jetskins/isaac/apps/carter/carter_sim/bridge_config/carter_full.json"

Everything seems fine but when I play the simulation, I get:

2020-05-29 18:37:07.554 INFO packages/navigation/RandomWalk.cpp@76: Picked a new goal: p=(27.185358, 46.500653), q=-2.558233
terminate called after throwing an instance of ‘kj::ExceptionImpl’
what(): capnp/layout.c++:2169: failed: expected ref->kind() == WirePointer::STRUCT; Message contains non-struct pointer where struct pointer was expected.
Everything seemsstack: 7fb0e4fe5382 7fb0e4fe703f 7fb0e4fe1544 7fb0e5075b26 7fb0e5076343 7fb0e4fe17fc 5643f4ef2a75 5643f4f5c4f5 5643f4e8ea0b 7fb0e85146de 7fb0e87e76da 7fb0e7f6f88e

| Isaac application terminated unexpectedly |

However, port 5000 is opened by Unreal simulation and netcat receives lidar messages.

The structure of the Lidar message appears to be incorrect.
When I delete the lidar in the configuration file, I can see the camera messages in Websight. It therefore seems that it is the lidar structure which is incorrect and which ends the program.
Thanks for your help!

Hi Michel,

were you able to fix this problem? I’m facing the same issue.

Hello there,

This errore show when there is an error in capnProto when sending data with TCP,

Isaac sim seems to be waiting for a pointer but you are sending a value

I know why this error is showing but don’t know how to solve it so good luck,