source/isaaclab/test/sensors/check_contact_sensor.py

# Copyright (c) 2022-2026, The Isaac Lab Project Developers (https://github.com/isaac-sim/IsaacLab/blob/main/CONTRIBUTORS.md).
# All rights reserved.
#
# SPDX-License-Identifier: BSD-3-Clause

"""
This script demonstrates how to use the contact sensor sensor in Isaac Lab.

.. code-block:: bash

    ./isaaclab.sh -p source/isaaclab/test/sensors/test_contact_sensor.py --num_robots 2
"""

"""Launch Isaac Sim Simulator first."""


import argparse

from isaaclab.app import AppLauncher

# add argparse arguments
parser = argparse.ArgumentParser(description="Contact Sensor Test Script")
parser.add_argument("--num_robots", type=int, default=128, help="Number of robots to spawn.")

# append AppLauncher cli args
AppLauncher.add_app_launcher_args(parser)
# parse the arguments
args_cli = parser.parse_args()

# launch omniverse app
app_launcher = AppLauncher(args_cli)
simulation_app = app_launcher.app


"""Rest everything follows."""

import torch

from isaacsim.core.api.simulation_context import SimulationContext
from isaacsim.core.cloner import GridCloner
from isaacsim.core.utils.viewports import set_camera_view

import isaaclab.sim as sim_utils
from isaaclab.assets import Articulation
from isaaclab.sensors.contact_sensor import ContactSensor, ContactSensorCfg
from isaaclab.utils.timer import Timer

##
# Pre-defined configs
##
from isaaclab_assets.robots.anymal import ANYMAL_C_CFG  # isort:skip


"""
Helpers
"""


def design_scene():
    """Add prims to the scene."""
    # Ground-plane
    cfg = sim_utils.GroundPlaneCfg()
    cfg.func("/World/defaultGroundPlane", cfg)
    # Lights
    cfg = sim_utils.DomeLightCfg(intensity=2000)
    cfg.func("/World/Light/DomeLight", cfg, translation=(-4.5, 3.5, 10.0))


"""
Main
"""


def main():
    """Spawns the ANYmal robot and clones it using Isaac Sim Cloner API."""

    # Load kit helper
    sim = SimulationContext(physics_dt=0.005, rendering_dt=0.005, backend="torch", device="cuda:0")
    # Set main camera
    set_camera_view([2.5, 2.5, 2.5], [0.0, 0.0, 0.0])

    # Enable hydra scene-graph instancing
    # this is needed to visualize the scene when flatcache is enabled
    sim._settings.set_bool("/persistent/omnihydra/useSceneGraphInstancing", True)

    # Create interface to clone the scene
    cloner = GridCloner(spacing=2.0)
    cloner.define_base_env("/World/envs")
    # Everything under the namespace "/World/envs/env_0" will be cloned
    sim.stage.DefinePrim("/World/envs/env_0", "Xform")
    # Clone the scene
    num_envs = args_cli.num_robots
    cloner.define_base_env("/World/envs")
    envs_prim_paths = cloner.generate_paths("/World/envs/env", num_paths=num_envs)
    _ = cloner.clone(source_prim_path="/World/envs/env_0", prim_paths=envs_prim_paths, replicate_physics=True)
    # Design props
    design_scene()
    # Spawn things into the scene
    robot_cfg = ANYMAL_C_CFG.replace(prim_path="/World/envs/env_.*/Robot")
    robot_cfg.spawn.activate_contact_sensors = True
    robot = Articulation(cfg=robot_cfg)
    # Contact sensor
    contact_sensor_cfg = ContactSensorCfg(
        prim_path="/World/envs/env_.*/Robot/.*_FOOT",
        track_air_time=True,
        track_contact_points=True,
        track_friction_forces=True,
        debug_vis=False,  # not args_cli.headless,
        filter_prim_paths_expr=["/World/defaultGroundPlane/GroundPlane/CollisionPlane"],
    )
    contact_sensor = ContactSensor(cfg=contact_sensor_cfg)
    # filter collisions within each environment instance
    physics_scene_path = sim.get_physics_context().prim_path
    cloner.filter_collisions(
        physics_scene_path, "/World/collisions", envs_prim_paths, global_paths=["/World/defaultGroundPlane"]
    )

    # Play the simulator
    sim.reset()
    # print info
    print(contact_sensor)

    # Now we are ready!
    print("[INFO]: Setup complete...")

    # Define simulation stepping
    decimation = 4
    physics_dt = sim.get_physics_dt()
    sim_dt = decimation * physics_dt
    sim_time = 0.0
    count = 0
    dt = []
    # Simulate physics
    while simulation_app.is_running():
        # If simulation is stopped, then exit.
        if sim.is_stopped():
            break
        # If simulation is paused, then skip.
        if not sim.is_playing():
            sim.step(render=False)
            continue
        # reset
        if count % 1000 == 0 and count != 0:
            # reset counters
            sim_time = 0.0
            count = 0
            print("=" * 80)
            print("avg dt real-time", sum(dt) / len(dt))
            print("=" * 80)

            # reset dof state
            joint_pos, joint_vel = robot.data.default_joint_pos, robot.data.default_joint_vel
            robot.write_joint_state_to_sim(joint_pos, joint_vel)
            robot.reset()
            dt = []

        # perform 4 steps
        for _ in range(decimation):
            # apply actions
            robot.set_joint_position_target(robot.data.default_joint_pos)
            # write commands to sim
            robot.write_data_to_sim()
            # perform step
            sim.step()
            # fetch data
            robot.update(physics_dt)
        # update sim-time
        sim_time += sim_dt
        count += 1
        # update the buffers
        if sim.is_playing():
            with Timer() as timer:
                contact_sensor.update(sim_dt, force_recompute=True)
                dt.append(timer.time_elapsed)

            contact_sensor.update(sim_dt, force_recompute=True)
            if count % 100 == 0:
                print("Sim-time: ", sim_time)
                print("Number of contacts: ", torch.count_nonzero(contact_sensor.data.current_air_time == 0.0).item())
                print("-" * 80)


if __name__ == "__main__":
    # run the main function
    main()
    # close sim app
    simulation_app.close()