Is the Legged Gym issue with force sensor still there ?

[vicltz]

The Legged Gym repository says this about force sensors in its README:
https://github.com/leggedrobotics/legged_gym?tab=readme-ov-file#known-issues

Known Issues

The contact forces reported by net_contact_force_tensor are unreliable when simulating on GPU with a triangle mesh terrain. A workaround is to use force sensors, but the force are propagated through the sensors of consecutive bodies resulting in an undesirable behaviour. However, for a legged robot it is possible to add sensors to the feet/end effector only and get the expected results. When using the force sensors make sure to exclude gravity from the reported forces with sensor_options.enable_forward_dynamics_forces. Example:

sensor_pose = gymapi.Transform()
for name in feet_names:
    sensor_options = gymapi.ForceSensorProperties()
    sensor_options.enable_forward_dynamics_forces = False # for example gravity
    sensor_options.enable_constraint_solver_forces = True # for example contacts
    sensor_options.use_world_frame = True # report forces in world frame (easier to get vertical components)
    index = self.gym.find_asset_rigid_body_index(robot_asset, name)
    self.gym.create_asset_force_sensor(robot_asset, index, sensor_pose, sensor_options)
(...)

sensor_tensor = self.gym.acquire_force_sensor_tensor(self.sim)
self.gym.refresh_force_sensor_tensor(self.sim)
force_sensor_readings = gymtorch.wrap_tensor(sensor_tensor)
self.sensor_forces = force_sensor_readings.view(self.num_envs, 4, 6)[..., :3]
(...)

self.gym.refresh_force_sensor_tensor(self.sim)
contact = self.sensor_forces[:, :, 2] > 1.

Since Isaac Sim uses PhysX as a backend, is this issue still there ?
I suspect issues with feet collisions / sensors while training locomotion policies.

Thanks

[RandomOakForest]

Thank you for posting this. I'm verifying with the PhysX team, and should have an answer soon.

[RandomOakForest]

Following up, the team deprecated and removed the force sensors, and introduced the link incoming joint force instead, that allows implementing load cells and reading out active and passive joint forces transmitted between the articulation links. The new API and feature is available in IsaacSim here and in IsaacLab in this doc.