[FEATURE] Add dedicated sensor manager.

genesis/engine/scene.py

@@ -26,6 +26,7 @@
     PBDOptions,
     ProfilingOptions,
     RigidOptions,
+    SensorOptions,
     SFOptions,
     SimOptions,
     SPHOptions,
@@ -514,6 +515,10 @@ def add_light(
         else:
             gs.raise_exception("Adding lights is only supported by 'RayTracer' and 'BatchRenderer'.")
 
+    @gs.assert_unbuilt
+    def add_sensor(self, sensor_options: SensorOptions):
+        return self._sim._sensor_manager.create_sensor(sensor_options)
+
     @gs.assert_unbuilt
     def add_camera(
         self,

genesis/engine/simulator.py

@@ -36,6 +36,7 @@
 )
 from .states.cache import QueriedStates
 from .states.solvers import SimState
+from genesis.sensors.sensor_manager import SensorManager
 
 if TYPE_CHECKING:
     from genesis.engine.scene import Scene
@@ -151,6 +152,9 @@ def __init__(
         # entities
         self._entities: list[Entity] = gs.List()
 
+        # sensors
+        self._sensor_manager = SensorManager(self)
+
     def _add_entity(self, morph: Morph, material, surface, visualize_contact=False):
         if isinstance(material, gs.materials.Tool):
             entity = self.tool_solver.add_entity(self.n_entities, material, morph, surface)
@@ -206,6 +210,8 @@ def build(self):
         if self.n_envs > 0 and self.sf_solver.is_active():
             gs.raise_exception("Batching is not supported for SF solver as of now.")
 
+        self._sensor_manager.build()
+
         # hybrid
         for entity in self._entities:
             if isinstance(entity, HybridEntity):
@@ -275,6 +281,8 @@ def step(self, in_backward=False):
         if self.rigid_solver.is_active():
             self.rigid_solver.clear_external_force()
 
+        self._sensor_manager.step()
+
     def _step_grad(self):
         for _ in range(self._substeps - 1, -1, -1):
 

genesis/options/__init__.py

@@ -2,6 +2,6 @@
 from .solvers import *
 from .vis import *
 from .profiling import ProfilingOptions
-
+from .sensors import SensorOptions
 
 __all__ = ["ProfilingOptions"]

genesis/options/sensors.py

@@ -0,0 +1,16 @@
+from genesis.options import Options
+
+
+class SensorOptions(Options):
+    """
+    Base class for all sensor options.
+    Each sensor should have their own options class that inherits from this class.
+    The options class should be registered with the SensorManager using the @register_sensor decorator.
+
+    Parameters
+    ----------
+    read_delay : float
+        The delay in seconds before the sensor data is read.
+    """
+
+    read_delay: float = 0.0

genesis/sensors/base_sensor.py

@@ -1,21 +1,130 @@
+from typing import TYPE_CHECKING, Any, List, Type
+
+import numpy as np
 import taichi as ti
-import genesis as gs
+import torch
 
-from typing import List, Optional
+import genesis as gs
 from genesis.repr_base import RBC
 
+if TYPE_CHECKING:
+    from genesis.options.sensors import SensorOptions
+    from genesis.utils.ring_buffer import TensorRingBuffer
+
+    from .sensor_manager import SensorManager
+
 
 @ti.data_oriented
 class Sensor(RBC):
     """
     Base class for all types of sensors.
-    A sensor must have a read() method that returns the sensor data.
     """
 
+    def __init__(self, sensor_options: "SensorOptions", sensor_idx: int, sensor_manager: "SensorManager"):
+        self._options: "SensorOptions" = sensor_options
+        self._idx: int = sensor_idx
+        self._manager: "SensorManager" = sensor_manager
+
+        # initialized by SensorManager during build
+        self._read_delay_steps: int = 0
+        self._shape_indices: list[tuple[int, int]] = []
+        self._shared_metadata: dict[str, Any] | None = None
+        self._cache: "TensorRingBuffer" | None = None
+
+    # =============================== implementable methods ===============================
+
+    def build(self):
+        """
+        This method is called by the SensorManager during the scene build phase to initialize the sensor.
+        This is where any shared metadata should be initialized.
+        """
+        raise NotImplementedError("Sensors must implement `build()`.")
+
+    def _get_return_format(self) -> dict[str, tuple[int, ...]] | tuple[int, ...]:
+        """
+        Data format of the read() return value.
+
+        Returns
+        -------
+        return_format : dict | tuple
+            - If tuple, the final shape of the read() return value.
+                e.g. (2, 3) means read() will return a tensor of shape (2, 3).
+            - If dict a dictionary with string keys and tensor values will be returned.
+                e.g. {"pos": (3,), "quat": (4,)} returns a dict of tensors [0:3] and [3:7] from the cache.
+        """
+        raise NotImplementedError("Sensors must implement `return_format()`.")
+
+    def _get_cache_length(self) -> int:
+        """
+        The length of the cache for this sensor instance, e.g. number of points for a Lidar point cloud.
+        """
+        raise NotImplementedError("Sensors must implement `cache_length()`.")
+
+    @classmethod
+    def _update_shared_ground_truth_cache(
+        cls, shared_metadata: dict[str, Any], shared_ground_truth_cache: torch.Tensor
+    ):
+        """
+        Update the shared sensor ground truth cache for all sensors of this class using metadata in SensorManager.
+        """
+        raise NotImplementedError("Sensors must implement `update_shared_ground_truth_cache()`.")
+
+    @classmethod
+    def _update_shared_cache(
+        cls, shared_metadata: dict[str, Any], shared_ground_truth_cache: torch.Tensor, shared_cache: "TensorRingBuffer"
+    ):
+        """
+        Update the shared sensor cache for all sensors of this class using metadata in SensorManager.
+        """
+        raise NotImplementedError("Sensors must implement `update_shared_cache()`.")
+
+    @classmethod
+    def _get_cache_dtype(cls) -> torch.dtype:
+        """
+        The dtype of the cache for this sensor.
+        """
+        raise NotImplementedError("Sensors must implement `get_cache_dtype()`.")
+
+    # =============================== shared methods ===============================
+
     @gs.assert_built
-    def read(self, envs_idx: Optional[List[int]] = None):
+    def read(self, envs_idx: List[int] | None = None):
         """
-        Read the sensor data.
-        Sensor implementations should ideally cache the data to avoid unnecessary computations.
+        Read the sensor data (with noise applied if applicable).
         """
-        raise NotImplementedError("The Sensor subclass must implement `read()`.")
+        return self._get_formatted_data(self._cache.get(self._read_delay_steps), envs_idx)
+
+    @gs.assert_built
+    def read_ground_truth(self, envs_idx: List[int] | None = None):
+        """
+        Read the ground truth sensor data (without noise).
+        """
+        return self._get_formatted_data(self._manager.get_cloned_from_ground_truth_cache(self), envs_idx)
+
+    def _get_formatted_data(
+        self, tensor: torch.Tensor, envs_idx: list[int] | None
+    ) -> torch.Tensor | dict[str, torch.Tensor]:
+        # Note: This method does not clone the data tensor, it should have been cloned by the caller.
+
+        if envs_idx is None:
+            envs_idx = self._manager._sim._scene._envs_idx
+
+        return_format = self._get_return_format()
+        return_shapes = return_format.values() if isinstance(return_format, dict) else (return_format,)
+        return_values = []
+
+        for i, shape in enumerate(return_shapes):
+            start_idx, end_idx = self._shape_indices[i]
+            value = tensor[envs_idx, start_idx:end_idx].reshape(len(envs_idx), *shape).squeeze()
+            if self._manager._sim.n_envs == 0:
+                value = value.squeeze(0)
+            return_values.append(value)
+
+        if isinstance(return_format, dict):
+            return dict(zip(return_format.keys(), return_values))
+        else:
+            return return_values[0]
+
+    @property
+    def is_built(self) -> bool:
+        return self._manager._sim._scene._is_built

genesis/sensors/sensor_manager.py

@@ -0,0 +1,114 @@
+from typing import TYPE_CHECKING, Any, Type
+
+import numpy as np
+import torch
+
+import genesis as gs
+from genesis.utils.ring_buffer import TensorRingBuffer
+
+if TYPE_CHECKING:
+    from genesis.options.sensors import SensorOptions
+
+    from .base_sensor import Sensor
+
+
+class SensorManager:
+    SENSOR_TYPES_MAP: dict[Type["SensorOptions"], Type["Sensor"]] = {}
+
+    def __init__(self, sim):
+        self._sim = sim
+        self._sensors_by_type: dict[Type["Sensor"], list["Sensor"]] = {}
+        self._sensors_metadata: dict[Type["Sensor"], dict[str, Any]] = {}
+        self._ground_truth_cache: dict[Type[torch.dtype], torch.Tensor] = {}
+        self._cache: dict[Type[torch.dtype], TensorRingBuffer] = {}
+        self._cache_slices_by_type: dict[Type["Sensor"], slice] = {}
+
+        self._last_ground_truth_cache_cloned_step: dict[Type[torch.dtype], int] = {}
+        self._cloned_ground_truth_cache: dict[Type[torch.dtype], torch.Tensor] = {}
+
+    def create_sensor(self, sensor_options: "SensorOptions"):
+        sensor_cls = SensorManager.SENSOR_TYPES_MAP[type(sensor_options)]
+        self._sensors_by_type.setdefault(sensor_cls, [])
+        sensor = sensor_cls(sensor_options, len(self._sensors_by_type[sensor_cls]), self)
+        self._sensors_by_type[sensor_cls].append(sensor)
+        return sensor
+
+    def build(self):
+        max_cache_buf_len = 0
+        cache_size_per_dtype = {}
+        for sensor_cls, sensors in self._sensors_by_type.items():
+            self._sensors_metadata[sensor_cls] = {}
+            dtype = sensor_cls._get_cache_dtype()
+            cache_size_per_dtype.setdefault(dtype, 0)
+            cls_cache_start_idx = cache_size_per_dtype[dtype]
+
+            for sensor in sensors:
+                return_format = sensor._get_return_format()
+                return_shapes = return_format.values() if isinstance(return_format, dict) else (return_format,)
+
+                tensor_size = 0
+                for shape in return_shapes:
+                    data_size = np.prod(shape)
+                    sensor._shape_indices.append((tensor_size, tensor_size + data_size))
+                    tensor_size += data_size
+
+                delay_steps_float = sensor._options.read_delay / self._sim.dt
+                sensor._read_delay_steps = round(delay_steps_float)
+                if not np.isclose(delay_steps_float, sensor._read_delay_steps, atol=1e-6):
+                    gs.logger.warn(
+                        f"Read delay should be a multiple of the simulation time step. Got {sensor._options.read_delay}"
+                        f" and {self._sim.dt}. Actual read delay will be {1/sensor._read_delay_steps}."
+                    )
+
+                sensor._cache_size = sensor._get_cache_length() * tensor_size
+                sensor._cache_idx = cache_size_per_dtype[dtype]
+                cache_size_per_dtype[dtype] += sensor._cache_size
+
+                max_cache_buf_len = max(max_cache_buf_len, sensor._read_delay_steps + 1)
+
+            cls_cache_end_idx = cache_size_per_dtype[dtype]
+            self._cache_slices_by_type[sensor_cls] = slice(cls_cache_start_idx, cls_cache_end_idx)
+
+        for dtype in cache_size_per_dtype.keys():
+            cache_shape = (self._sim._B, cache_size_per_dtype[dtype])
+            self._ground_truth_cache[dtype] = torch.zeros(cache_shape, dtype=dtype)
+            self._cache[dtype] = TensorRingBuffer(max_cache_buf_len, cache_shape, dtype=dtype)
+
+        for sensor_cls, sensors in self._sensors_by_type.items():
+            dtype = sensor_cls._get_cache_dtype()
+            for sensor in sensors:
+                sensor._shared_metadata = self._sensors_metadata[sensor_cls]
+                sensor._cache = self._cache[dtype][:, sensor._cache_idx : sensor._cache_idx + sensor._cache_size]
+                sensor.build()
+
+    def step(self):
+        for sensor_cls in self._sensors_by_type.keys():
+            dtype = sensor_cls._get_cache_dtype()
+            cache_slice = self._cache_slices_by_type[sensor_cls]
+            sensor_cls._update_shared_ground_truth_cache(
+                self._sensors_metadata[sensor_cls], self._ground_truth_cache[dtype][cache_slice]
+            )
+            sensor_cls._update_shared_cache(
+                self._sensors_metadata[sensor_cls],
+                self._ground_truth_cache[dtype][cache_slice],
+                self._cache[dtype][cache_slice],
+            )
+
+    def get_cloned_from_ground_truth_cache(self, sensor: "Sensor") -> torch.Tensor:
+        dtype = sensor._get_cache_dtype()
+        if self._last_ground_truth_cache_cloned_step[dtype] != self._sim.cur_step_global:
+            self._last_ground_truth_cache_cloned_step[dtype] = self._sim.cur_step_global
+            self._cloned_ground_truth_cache[dtype] = self._ground_truth_cache[dtype].clone()
+        return self._cloned_ground_truth_cache[dtype][:, sensor._cache_idx : sensor._cache_idx + sensor._cache_size]
+
+    @property
+    def sensors(self):
+        return tuple([sensor for sensor_list in self._sensors_by_type.values() for sensor in sensor_list])
+
+
+def register_sensor(sensor_cls: Type["Sensor"]):
+    def _impl(options_cls: Type["SensorOptions"]):
+        SensorManager.SENSOR_TYPES_MAP[options_cls] = sensor_cls
+        return options_cls
+
+    return _impl