WIP

lerobot/common/policies/act/modeling_act.py

@@ -20,8 +20,10 @@ The majority of changes here involve removing unused code, unifying naming, and
 """
 
 import math
-from collections import deque
+import threading
+import time
 from itertools import chain
+from threading import Thread
 from typing import Callable
 
 import einops
@@ -36,6 +38,7 @@ from torchvision.ops.misc import FrozenBatchNorm2d
 
 from lerobot.common.policies.act.configuration_act import ACTConfig
 from lerobot.common.policies.normalize import Normalize, Unnormalize
+from lerobot.common.policies.utils import TemporalQueue
 
 
 class ACTPolicy(
@@ -87,22 +90,23 @@ class ACTPolicy(
             self.temporal_ensembler = ACTTemporalEnsembler(config.temporal_ensemble_coeff, config.chunk_size)
 
         self.reset()
+        self.thread = None
+
+        # TODO(rcadene): Add delta timestamps in policy
+        FPS = 10  # noqa: N806
+        self.delta_timestamps = [i / FPS for i in range(self.config.n_action_steps)]
 
     def reset(self):
         """This should be called whenever the environment is reset."""
         if self.config.temporal_ensemble_coeff is not None:
             self.temporal_ensembler.reset()
         else:
-            self._action_queue = deque([], maxlen=self.config.n_action_steps)
+            # TODO(rcadene): set proper maxlen
+            self._obs_queue = TemporalQueue(maxlen=1)
+            self._action_queue = TemporalQueue(maxlen=200)
 
     @torch.no_grad
-    def select_action(self, batch: dict[str, Tensor]) -> Tensor:
+    def inference(self, batch: dict[str, Tensor]) -> Tensor:
-        """Select a single action given environment observations.
-
-        This method wraps `select_actions` in order to return one action at a time for execution in the
-        environment. It works by managing the actions in a queue and only calling `select_actions` when the
-        queue is empty.
-        """
         self.eval()
 
         batch = self.normalize_inputs(batch)
@@ -118,18 +122,47 @@ class ACTPolicy(
             action = self.temporal_ensembler.update(actions)
             return action
 
-        # Action queue logic for n_action_steps > 1. When the action_queue is depleted, populate it by
+        actions = self.model(batch)[0][:, : self.config.n_action_steps]
-        # querying the policy.
-        if len(self._action_queue) == 0:
-            actions = self.model(batch)[0][:, : self.config.n_action_steps]
 
-            # TODO(rcadene): make _forward return output dictionary?
+        # TODO(rcadene): make _forward return output dictionary?
-            actions = self.unnormalize_outputs({"action": actions})["action"]
+        actions = self.unnormalize_outputs({"action": actions})["action"]
+        return actions
 
-            # `self.model.forward` returns a (batch_size, n_action_steps, action_dim) tensor, but the queue
+    def inference_loop(self):
-            # effectively has shape (n_action_steps, batch_size, *), hence the transpose.
+        prev_timestamp = None
-            self._action_queue.extend(actions.transpose(0, 1))
+        while not self.stop_event.is_set():
-        return self._action_queue.popleft()
+            last_observation, last_timestamp = self._obs_queue.get_latest()
+
+            if prev_timestamp is not None and prev_timestamp == last_timestamp:
+                # in case inference ran faster than recording/adding a new observation in the queue
+                time.sleep(0.1)
+                continue
+
+            pred_action_sequence = self.inference(last_observation)
+
+            for action, delta_ts in zip(pred_action_sequence, self.delta_timestamps, strict=False):
+                self._action_queue.add(action, last_timestamp + delta_ts)
+
+            prev_timestamp = last_timestamp
+
+    def select_action(self, batch: dict[str, Tensor]) -> Tensor:
+        present_time = time.time()
+        self._obs_queue.add(batch, present_time)
+
+        if self.thread is None:
+            self.stop_event = threading.Event()
+            self.thread = Thread(target=self.inference_loop, args=())
+            self.thread.daemon = True
+            self.thread.start()
+
+        next_action = None
+        while next_action is None:
+            try:
+                next_action = self._action_queue.get(present_time)
+            except ValueError:
+                time.sleep(0.1)  # no action available at this present time, we wait a bit
+
+        return next_action
 
     def forward(self, batch: dict[str, Tensor]) -> dict[str, Tensor]:
         """Run the batch through the model and compute the loss for training or validation."""

lerobot/common/policies/utils.py

@@ -13,6 +13,8 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+from collections import deque
+
 import torch
 from torch import nn
 
@@ -47,3 +49,33 @@ def get_dtype_from_parameters(module: nn.Module) -> torch.dtype:
     Note: assumes that all parameters have the same dtype.
     """
     return next(iter(module.parameters())).dtype
+
+
+class TemporalQueue:
+    def __init__(self, maxlen):
+        # TODO(rcadene): set proper maxlen
+        self.items = deque(maxlen=maxlen)
+        self.timestamps = deque(maxlen=maxlen)
+
+    def add(self, item, timestamp):
+        self.items.append(item)
+        self.timestamps.append(timestamp)
+
+    def get_latest(self):
+        return self.items[-1], self.timestamps[-1]
+
+    def get(self, timestamp):
+        import numpy as np
+
+        timestamps = np.array(list(self.timestamps))
+        distances = np.abs(timestamps - timestamp)
+        nearest_idx = distances.argmin()
+
+        # print(float(distances[nearest_idx]))
+        if float(distances[nearest_idx]) > 1 / 5:
+            raise ValueError()
+
+        return self.items[nearest_idx], self.timestamps[nearest_idx]
+
+    def __len__(self):
+        return len(self.items)

test2.py

@@ -0,0 +1,45 @@
+import torch
+
+from lerobot.common.datasets.factory import make_dataset
+from lerobot.common.policies.factory import make_policy
+from lerobot.common.utils.utils import init_hydra_config, set_global_seed
+from tests.utils import DEFAULT_CONFIG_PATH
+
+
+def main(env_name, policy_name, extra_overrides):
+    cfg = init_hydra_config(
+        DEFAULT_CONFIG_PATH,
+        overrides=[
+            f"env={env_name}",
+            f"policy={policy_name}",
+            "device=cpu",
+        ]
+        + extra_overrides,
+    )
+    set_global_seed(1337)
+    dataset = make_dataset(cfg)
+    policy = make_policy(cfg, dataset_stats=dataset.stats)
+
+    dataloader = torch.utils.data.DataLoader(
+        dataset,
+        num_workers=0,
+        batch_size=1,
+        shuffle=False,
+    )
+    batch = next(iter(dataloader))
+
+    obs = {}
+    for k in batch:
+        if k.startswith("observation"):
+            obs[k] = batch[k]
+
+    actions = policy.inference(obs)
+
+    action, timestamp = policy.select_action(obs)
+
+    print(actions[0])
+    print(action)
+
+
+if __name__ == "__main__":
+    main("aloha", "act", ["policy.n_action_steps=10"])