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[FEATURE] Add noise options for tactile sensors: hysteresis, dead taxels, probe gain #2813

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[FEATURE] Add noise options for tactile sensors: hysteresis, dead taxels, probe gain #2813

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8001139
rebase update
Milotrince May 24, 2026
ae61cc1
fix elastomertaxel is_grid
Milotrince May 24, 2026
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100 changes: 71 additions & 29 deletions examples/sensors/tactile_sandbox.py
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
"""
Interactive demo of tactile sensors on a fixed taxel pad (box or dome) with controllable objects.
Sensor types: ContactDepthProbe, ElastomerTaxel, KinematicTaxel, ProximityTaxel.
Sensor types: ContactDepthProbe, ContactProbe, ElastomerTaxel, KinematicTaxel, ProximityTaxel.

Note that the sensor readings here have not been calibrated to any units, and is purely for visualization purposes.
"""
Expand All @@ -24,9 +24,9 @@
from genesis.engine.entities.rigid_entity import RigidEntity
from genesis.engine.sensors.base_sensor import Sensor

KEY_DPOS = 0.005
KEY_DPOS = 0.001
FORCE_SCALE = 100.0
ROT_FORCE_SCALE = 200.0
ROT_FORCE_SCALE = 100.0

GRID_SIZE = 20 # 20x20 taxels for square
PROBE_RADIUS = 0.004
Expand All @@ -48,13 +48,23 @@ def _add_tactile_sensor(
probe_local_pos: np.ndarray,
probe_normal: tuple[float, float, float] | np.ndarray,
track_link_idx: tuple[int, ...],
noise: bool,
) -> "Sensor":
common = dict(
entity_idx=entity.idx,
link_idx_local=link_idx_local,
draw_debug=True,
probe_radius=PROBE_RADIUS,
)
if noise:
# Sensor imperfections shared by every tactile sensor type: viscoelastic hysteresis on the measured
# branch, a noised sensing radius, and a per-taxel measured-branch depth gain.
common.update(
hysteresis_strength=0.5, # viscoelastic overshoot fraction
hysteresis_tau=0.1, # viscoelastic relaxation time constant (seconds)
probe_radius_noise=0.001, # additive sensing-radius noise (meters)
probe_gain=1.5, # per-taxel measured-branch depth gain
)
if sensor_type == "elastomer":
return scene.add_sensor(
gs.sensors.ElastomerTaxel(
Expand All @@ -63,7 +73,8 @@ def _add_tactile_sensor(
track_link_idx=track_link_idx,
n_sample_points=2000,
dilate_scale=1.0,
shear_scale=100.0,
shear_scale=2.0,
normal_exponent=1.0,
**common,
)
)
Expand All @@ -76,32 +87,44 @@ def _add_tactile_sensor(
**common,
)
)
if sensor_type == "contact":
# Schmitt-trigger thresholds (contact depth in meters): a taxel latches on above contact_threshold and
# only releases once the depth drops back below the lower release_threshold.
return scene.add_sensor(
gs.sensors.ContactProbe(
probe_local_pos=probe_local_pos,
contact_threshold=0.004,
release_threshold=0.002,
**common,
)
)
if sensor_type == "kinematic":
return scene.add_sensor(
gs.sensors.KinematicTaxel(
probe_local_pos=probe_local_pos,
probe_local_normal=probe_normal,
normal_stiffness=500.0,
normal_damping=1.0,
shear_scalar=5.0,
twist_scalar=5.0,
shear_scalar=4.0,
twist_scalar=4.0,
normal_exponent=1.5,
**common,
)
)

common["probe_radius"] = PROBE_RADIUS * 2
common["debug_point_cloud_radius"] = 0.001
common["probe_radius"] = PROBE_RADIUS * 5
if sensor_type == "proximity":
return scene.add_sensor(
gs.sensors.ProximityTaxel(
probe_local_pos=probe_local_pos,
track_link_idx=track_link_idx,
n_sample_points=4000,
stiffness=200.0,
shear_coupling=100.0,
stiffness=40.0,
shear_coupling=10.0,
probe_local_normal=probe_normal,
probe_radius_noise=0.0001,
debug_point_cloud_radius=0.0005,
debug_probe_color=(0.2, 0.6, 1.0),
debug_contact_color=(1.0, 0.2, 0.2),
**common,
)
)
Expand All @@ -111,7 +134,6 @@ def _add_tactile_sensor(
def _plot_tactile_sensor(
scene: gs.Scene,
sensor_type: str,
labels: tuple[str, ...],
sensors: "tuple[Sensor, ...]",
n_envs: int = 1,
plot_normal: tuple[float, float, float] = (0.0, 0.0, -1.0),
Expand All @@ -122,24 +144,24 @@ def _plot_tactile_sensor(

if sensor_type == "elastomer":
for env_idx in range(n_envs):
for label, sensor in zip(labels, sensors):
for sensor in sensors:
scene.start_recording(
lambda s=sensor, i=env_idx: s.read()[i],
gs.recorders.MPLVectorFieldPlot(
title=f"({label} {OBJ_PER_ENV_LABELS[env_idx]}) ElastomerTaxel marker displacements",
title=f"({OBJ_PER_ENV_LABELS[env_idx]}) ElastomerTaxel marker displacements",
positions=sensor.probe_local_pos.reshape(-1, 3),
normal=plot_normal,
scale_factor=1.0,
max_magnitude=0.01,
scale_factor=0.1,
max_magnitude=0.1,
),
)
elif sensor_type == "kinematic":
for env_idx in range(n_envs):
for label, sensor in zip(labels, sensors):
for sensor in sensors:
scene.start_recording(
lambda s=sensor, i=env_idx: s.read().force[i],
gs.recorders.MPLVectorFieldPlot(
title=f"({label} {OBJ_PER_ENV_LABELS[env_idx]}) KinematicTaxel force",
title=f"({OBJ_PER_ENV_LABELS[env_idx]}) KinematicTaxel force",
positions=sensor.probe_local_pos.reshape(-1, 3),
normal=plot_normal,
scale_factor=0.01,
Expand All @@ -148,14 +170,14 @@ def _plot_tactile_sensor(
)
elif sensor_type == "proximity":
for env_idx in range(n_envs):
for label, sensor in zip(labels, sensors):
for sensor in sensors:
scene.start_recording(
lambda s=sensor, i=env_idx: s.read().force[i],
gs.recorders.MPLVectorFieldPlot(
title=f"({label} {OBJ_PER_ENV_LABELS[env_idx]}) ProximityTaxel force",
title=f"({OBJ_PER_ENV_LABELS[env_idx]}) ProximityTaxel force",
positions=sensor.probe_local_pos.reshape(-1, 3),
normal=plot_normal,
scale_factor=0.5,
scale_factor=0.1,
max_magnitude=1.0,
),
)
Expand All @@ -165,12 +187,22 @@ def _plot_tactile_sensor(
lambda i=env_idx: tuple(sensor.read()[i].max() for sensor in sensors),
gs.recorders.MPLLinePlot(
title=f"ContactDepthProbe max depth ({OBJ_PER_ENV_LABELS[env_idx]})",
labels=labels,
x_label="step",
y_label="depth",
history_length=200,
),
)
elif sensor_type == "contact":
for env_idx in range(n_envs):
scene.start_recording(
lambda i=env_idx: tuple(sensor.read()[i].sum() for sensor in sensors),
gs.recorders.MPLLinePlot(
title=f"ContactProbe taxels in contact ({OBJ_PER_ENV_LABELS[env_idx]})",
x_label="step",
y_label="# taxels",
history_length=200,
),
)


def _print_sensor_reading(sensor_type: str, sensor: "Sensor", t: float) -> None:
Expand All @@ -183,6 +215,10 @@ def _print_sensor_reading(sensor_type: str, sensor: "Sensor", t: float) -> None:
max_depth = data.max()
if max_depth > gs.EPS:
print(f"t={t:.2f}s max depth={max_depth:.4f}")
elif sensor_type == "contact":
n_contact = int(data.sum())
if n_contact > 0:
print(f"t={t:.2f}s taxels in contact={n_contact}")
elif sensor_type == "kinematic":
magnitude = torch.linalg.norm(data.force, axis=-1).max()
if magnitude > gs.EPS:
Expand All @@ -204,10 +240,15 @@ def main() -> None:
parser.add_argument("--dome", action="store_true", help="Change the sensor object to a dome instead of a box")
parser.add_argument(
"--sensor",
choices=("elastomer", "depth", "kinematic", "proximity"),
choices=("elastomer", "depth", "contact", "kinematic", "proximity"),
default="elastomer",
help="Type of tactile sensor to use.",
)
parser.add_argument(
"--noise",
action="store_true",
help="Enable sensor imperfections (viscoelastic hysteresis, probe_radius_noise, probe_gain).",
)
args = parser.parse_args()

gs.init(
Expand Down Expand Up @@ -276,17 +317,17 @@ def main() -> None:
ny=GRID_SIZE,
)

# Procedural torus written to a temp .obj (avoids checking a 2k-line mesh into the repo).
torus_path = os.path.join(tempfile.gettempdir(), "tactile_sandbox_torus.obj")
if not os.path.exists(torus_path):
trimesh.creation.torus(major_radius=0.3, minor_radius=0.1).export(torus_path)
trimesh.creation.torus(major_radius=1.0, minor_radius=0.5).export(torus_path)

obj = scene.add_entity(
morph=[
gs.morphs.Mesh(
file=torus_path,
euler=(90.0, 0.0, 0.0),
scale=OBJECT_SIZE,
euler=(0.0, 0.0, 0.0),
scale=OBJECT_SIZE * 2,
convexify=False,
),
gs.morphs.Sphere(
radius=OBJECT_SIZE / 2,
Expand Down Expand Up @@ -314,9 +355,10 @@ def main() -> None:
probe_local_pos,
probe_normal,
track_link_idx=(obj.base_link_idx,),
noise=args.noise,
)
if args.vis and "PYTEST_VERSION" not in os.environ:
_plot_tactile_sensor(scene, args.sensor, ("",), (sensor,), n_envs=4, plot_normal=probe_normal_axis)
_plot_tactile_sensor(scene, args.sensor, (sensor,), n_envs=4, plot_normal=probe_normal_axis)
scene.build(n_envs=4, env_spacing=(SENSOR_OBJ_SIZE * 1.2, SENSOR_OBJ_SIZE * 1.2))

obj_init_pos = tensor_to_array(obj.get_pos())
Expand Down Expand Up @@ -382,7 +424,7 @@ def rotate(axis_idx: int, is_negative: bool):
print("\n=== Tactile Sensor Sandbox ===")
n_taxels = probe_local_pos.reshape(-1, 3).shape[0]
layout = f"dome ({GRID_SIZE} latitude rings)" if args.dome else f"plane grid {probe_local_pos.shape[:-1]}"
print(f"sensor={args.sensor}; taxels={n_taxels}; {layout}")
print(f"sensor={args.sensor}; taxels={n_taxels}; {layout}; noise={'on' if args.noise else 'off'}")
if args.vis and IS_MATPLOTLIB_AVAILABLE:
print("Matplotlib live plot enabled when supported.")
if args.vis:
Expand Down
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