[Question] Notes on using Contact Sensor

[shaoxiang]

Question about Contact Sensor

I added a contact sensor according to the example steps,
https://isaac-sim.github.io/IsaacLab/source/tutorials/04_sensors/add_sensors_on_robot.html
but when contact or collision occurs, the values in data.net_forces_w or data.net_forces_w_history are both 0, and the Contact Report in the prims physics in the scene has also been added. I also tried to add a callback according to the ContactReportDemo example in omni. physx. demos \ omni \ physxdemos, like:
self._contact_report_sub = get_physx_simulation_interface().subscribe_contact_report_events(self._on_contact_report_event)
but unfortunately, I couldn't listen for any contact events. I think I must have gotten something wrong. I also added collision attributes to objects. Can you provide more detailed tutorials, usage instructions, or precautions about contact sensors?

[shaoxiang]

I solved this problem by adding this sentence, Now this part of the code looks like this：

# add contact sensor
self._contact_sensor = ContactSensor(self.cfg.contact_sensor)
self.scene.sensors["contact_sensor"] = self._contact_sensor

I'm confused why I need to pass self._contact_sensor to self.scene.sensors ["contact_sensor"], This step solved my problem!

[Mayankm96]

Potentially, you are not calling the method to update the sensor data. This is implicitly handled by the scene.update() which iterates over all the entities and calls their methods to update the buffers.