Feat/add unitree g1 robot (#2530)

* add unitree_g1_robot_class

* finish locomotion loading code

* precommit

* separate groot locomotion logic

* remove leftover locomotion variable, unify kp kd

* format config

* properly comment config, example locomotion and unitree_g1 class

* ready to review

* download policy from the hub in `examples/unitree_g1/gr00t_locomotion`

* fix linter

* make precommit happy, add ignore flags

* linter pt3

* linter pt4

* [done] make precommit happy

* fix linter 5

* add docs

* push utils

* feat(robots): add Unitree G1 humanoid support with ZMQ bridge (#2539)

* feat(robots): add Unitree G1 humanoid support with ZMQ bridge

- Use JSON + base64 serialization for secure communication instead of pickle
- Add documentation section
- Rename robot_server to run_g1_server
- Add dependecies to pyproject.toml

* nit in docs

* remove globals use

* cast robot data to int/float

* ensure robot is connected before changing mode

* temperature can be list, average in such case

---------

Co-authored-by: Martino Russi <nopyeps@gmail.com>

* style nit

* remove transform_imu_data

* remove scipy dependency

* modify toml, add external unitree_sdk2py dep

* return actions from send_action

* cleaning

* add instructions for local deployment

* Update src/lerobot/robots/unitree_g1/unitree_g1.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Signed-off-by: Martino Russi <77496684+nepyope@users.noreply.github.com>

* update config and readme

* update docs

* update docs

* remove torch import

* fix docs

* remove ip from docs

* add licence header

---------

Signed-off-by: Martino Russi <77496684+nepyope@users.noreply.github.com>
Co-authored-by: Michel Aractingi <michel.aractingi@huggingface.co>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

src/lerobot/robots/unitree_g1/__init__.py

@@ -0,0 +1,18 @@
+#!/usr/bin/env python
+
+# Copyright 2025 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# 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 .config_unitree_g1 import UnitreeG1Config
+from .unitree_g1 import UnitreeG1

src/lerobot/robots/unitree_g1/config_unitree_g1.py

@@ -0,0 +1,55 @@
+#!/usr/bin/env python
+
+# Copyright 2025 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# 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 dataclasses import dataclass, field
+
+from ..config import RobotConfig
+
+_GAINS: dict[str, dict[str, list[float]]] = {
+    "left_leg": {
+        "kp": [150, 150, 150, 300, 40, 40],
+        "kd": [2, 2, 2, 4, 2, 2],
+    },  # pitch, roll, yaw, knee, ankle_pitch, ankle_roll
+    "right_leg": {"kp": [150, 150, 150, 300, 40, 40], "kd": [2, 2, 2, 4, 2, 2]},
+    "waist": {"kp": [250, 250, 250], "kd": [5, 5, 5]},  # yaw, roll, pitch
+    "left_arm": {"kp": [80, 80, 80, 80], "kd": [3, 3, 3, 3]},  # shoulder_pitch/roll/yaw, elbow
+    "left_wrist": {"kp": [40, 40, 40], "kd": [1.5, 1.5, 1.5]},  # roll, pitch, yaw
+    "right_arm": {"kp": [80, 80, 80, 80], "kd": [3, 3, 3, 3]},
+    "right_wrist": {"kp": [40, 40, 40], "kd": [1.5, 1.5, 1.5]},
+    "other": {"kp": [80, 80, 80, 80, 80, 80], "kd": [3, 3, 3, 3, 3, 3]},
+}
+
+
+def _build_gains() -> tuple[list[float], list[float]]:
+    """Build kp and kd lists from body-part groupings."""
+    kp = [v for g in _GAINS.values() for v in g["kp"]]
+    kd = [v for g in _GAINS.values() for v in g["kd"]]
+    return kp, kd
+
+
+_DEFAULT_KP, _DEFAULT_KD = _build_gains()
+
+
+@RobotConfig.register_subclass("unitree_g1")
+@dataclass
+class UnitreeG1Config(RobotConfig):
+    kp: list[float] = field(default_factory=lambda: _DEFAULT_KP.copy())
+    kd: list[float] = field(default_factory=lambda: _DEFAULT_KD.copy())
+
+    control_dt: float = 1.0 / 250.0  # 250Hz
+
+    # socket config for ZMQ bridge
+    robot_ip: str = "192.168.123.164"

src/lerobot/robots/unitree_g1/g1_utils.py

@@ -0,0 +1,89 @@
+#!/usr/bin/env python
+
+# Copyright 2025 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# 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 enum import IntEnum
+
+# ruff: noqa: N801, N815
+
+NUM_MOTORS = 35
+
+
+class G1_29_JointArmIndex(IntEnum):
+    # Left arm
+    kLeftShoulderPitch = 15
+    kLeftShoulderRoll = 16
+    kLeftShoulderYaw = 17
+    kLeftElbow = 18
+    kLeftWristRoll = 19
+    kLeftWristPitch = 20
+    kLeftWristyaw = 21
+
+    # Right arm
+    kRightShoulderPitch = 22
+    kRightShoulderRoll = 23
+    kRightShoulderYaw = 24
+    kRightElbow = 25
+    kRightWristRoll = 26
+    kRightWristPitch = 27
+    kRightWristYaw = 28
+
+
+class G1_29_JointIndex(IntEnum):
+    # Left leg
+    kLeftHipPitch = 0
+    kLeftHipRoll = 1
+    kLeftHipYaw = 2
+    kLeftKnee = 3
+    kLeftAnklePitch = 4
+    kLeftAnkleRoll = 5
+
+    # Right leg
+    kRightHipPitch = 6
+    kRightHipRoll = 7
+    kRightHipYaw = 8
+    kRightKnee = 9
+    kRightAnklePitch = 10
+    kRightAnkleRoll = 11
+
+    kWaistYaw = 12
+    kWaistRoll = 13
+    kWaistPitch = 14
+
+    # Left arm
+    kLeftShoulderPitch = 15
+    kLeftShoulderRoll = 16
+    kLeftShoulderYaw = 17
+    kLeftElbow = 18
+    kLeftWristRoll = 19
+    kLeftWristPitch = 20
+    kLeftWristyaw = 21
+
+    # Right arm
+    kRightShoulderPitch = 22
+    kRightShoulderRoll = 23
+    kRightShoulderYaw = 24
+    kRightElbow = 25
+    kRightWristRoll = 26
+    kRightWristPitch = 27
+    kRightWristYaw = 28
+
+    # not used
+    kNotUsedJoint0 = 29
+    kNotUsedJoint1 = 30
+    kNotUsedJoint2 = 31
+    kNotUsedJoint3 = 32
+    kNotUsedJoint4 = 33
+    kNotUsedJoint5 = 34

src/lerobot/robots/unitree_g1/run_g1_server.py

@@ -0,0 +1,212 @@
+#!/usr/bin/env python3
+
+# Copyright 2025 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# 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.
+
+"""
+DDS-to-ZMQ bridge server for Unitree G1 robot.
+
+This server runs on the robot and forwards:
+- Robot state (LowState) from DDS to ZMQ (for remote clients)
+- Robot commands (LowCmd) from ZMQ to DDS (from remote clients)
+
+Uses JSON for secure serialization instead of pickle.
+"""
+
+import base64
+import contextlib
+import json
+import threading
+import time
+from typing import Any
+
+import zmq
+from unitree_sdk2py.comm.motion_switcher.motion_switcher_client import MotionSwitcherClient
+from unitree_sdk2py.core.channel import ChannelFactoryInitialize, ChannelPublisher, ChannelSubscriber
+from unitree_sdk2py.idl.default import unitree_hg_msg_dds__LowCmd_
+from unitree_sdk2py.idl.unitree_hg.msg.dds_ import LowCmd_ as hg_LowCmd, LowState_ as hg_LowState
+from unitree_sdk2py.utils.crc import CRC
+
+# DDS topic names follow Unitree SDK naming conventions
+# ruff: noqa: N816
+kTopicLowCommand_Debug = "rt/lowcmd"  # action to robot
+kTopicLowState = "rt/lowstate"  # observation from robot
+
+LOWCMD_PORT = 6000
+LOWSTATE_PORT = 6001
+NUM_MOTORS = 35
+
+
+def lowstate_to_dict(msg: hg_LowState) -> dict[str, Any]:
+    """Convert LowState SDK message to a JSON-serializable dictionary."""
+    motor_states = []
+    for i in range(NUM_MOTORS):
+        temp = msg.motor_state[i].temperature
+        avg_temp = float(sum(temp) / len(temp)) if isinstance(temp, list) else float(temp)
+        motor_states.append(
+            {
+                "q": float(msg.motor_state[i].q),
+                "dq": float(msg.motor_state[i].dq),
+                "tau_est": float(msg.motor_state[i].tau_est),
+                "temperature": avg_temp,
+            }
+        )
+
+    return {
+        "motor_state": motor_states,
+        "imu_state": {
+            "quaternion": [float(x) for x in msg.imu_state.quaternion],
+            "gyroscope": [float(x) for x in msg.imu_state.gyroscope],
+            "accelerometer": [float(x) for x in msg.imu_state.accelerometer],
+            "rpy": [float(x) for x in msg.imu_state.rpy],
+            "temperature": float(msg.imu_state.temperature),
+        },
+        # Encode bytes as base64 for JSON compatibility
+        "wireless_remote": base64.b64encode(bytes(msg.wireless_remote)).decode("ascii"),
+        "mode_machine": int(msg.mode_machine),
+    }
+
+
+def dict_to_lowcmd(data: dict[str, Any]) -> hg_LowCmd:
+    """Convert dictionary back to LowCmd SDK message."""
+    cmd = unitree_hg_msg_dds__LowCmd_()
+    cmd.mode_pr = data.get("mode_pr", 0)
+    cmd.mode_machine = data.get("mode_machine", 0)
+
+    for i, motor_data in enumerate(data.get("motor_cmd", [])):
+        cmd.motor_cmd[i].mode = motor_data.get("mode", 0)
+        cmd.motor_cmd[i].q = motor_data.get("q", 0.0)
+        cmd.motor_cmd[i].dq = motor_data.get("dq", 0.0)
+        cmd.motor_cmd[i].kp = motor_data.get("kp", 0.0)
+        cmd.motor_cmd[i].kd = motor_data.get("kd", 0.0)
+        cmd.motor_cmd[i].tau = motor_data.get("tau", 0.0)
+
+    return cmd
+
+
+def state_forward_loop(
+    lowstate_sub: ChannelSubscriber,
+    lowstate_sock: zmq.Socket,
+    state_period: float,
+) -> None:
+    """Read observation from DDS and forward to ZMQ clients."""
+    last_state_time = 0.0
+
+    while True:
+        # read from DDS
+        msg = lowstate_sub.Read()
+        if msg is None:
+            continue
+
+        now = time.time()
+        # optional downsampling (if robot dds rate > state_period)
+        if now - last_state_time >= state_period:
+            # Convert to dict and serialize with JSON
+            state_dict = lowstate_to_dict(msg)
+            payload = json.dumps({"topic": kTopicLowState, "data": state_dict}).encode("utf-8")
+            # if no subscribers / tx buffer full, just drop
+            with contextlib.suppress(zmq.Again):
+                lowstate_sock.send(payload, zmq.NOBLOCK)
+            last_state_time = now
+
+
+def cmd_forward_loop(
+    lowcmd_sock: zmq.Socket,
+    lowcmd_pub_debug: ChannelPublisher,
+    crc: CRC,
+) -> None:
+    """Receive commands from ZMQ and forward to DDS."""
+    while True:
+        payload = lowcmd_sock.recv()
+        msg_dict = json.loads(payload.decode("utf-8"))
+
+        topic = msg_dict.get("topic", "")
+        cmd_data = msg_dict.get("data", {})
+
+        # Reconstruct LowCmd object from dict
+        cmd = dict_to_lowcmd(cmd_data)
+
+        # recompute crc
+        cmd.crc = crc.Crc(cmd)
+
+        if topic == kTopicLowCommand_Debug:
+            lowcmd_pub_debug.Write(cmd)
+
+
+def main() -> None:
+    """Main entry point for the robot server bridge."""
+    # initialize DDS
+    ChannelFactoryInitialize(0)
+
+    # stop all active publishers on the robot
+    msc = MotionSwitcherClient()
+    msc.SetTimeout(5.0)
+    msc.Init()
+
+    status, result = msc.CheckMode()
+    while result is not None and "name" in result and result["name"]:
+        msc.ReleaseMode()
+        status, result = msc.CheckMode()
+        time.sleep(1.0)
+
+    crc = CRC()
+
+    # initialize DDS publisher
+    lowcmd_pub_debug = ChannelPublisher(kTopicLowCommand_Debug, hg_LowCmd)
+    lowcmd_pub_debug.Init()
+
+    # initialize DDS subscriber
+    lowstate_sub = ChannelSubscriber(kTopicLowState, hg_LowState)
+    lowstate_sub.Init()
+
+    # initialize ZMQ
+    ctx = zmq.Context.instance()
+
+    # receive commands from remote client
+    lowcmd_sock = ctx.socket(zmq.PULL)
+    lowcmd_sock.bind(f"tcp://0.0.0.0:{LOWCMD_PORT}")
+
+    # publish state to remote clients
+    lowstate_sock = ctx.socket(zmq.PUB)
+    lowstate_sock.bind(f"tcp://0.0.0.0:{LOWSTATE_PORT}")
+
+    state_period = 0.002  # ~500 hz
+
+    # start observation forwarding thread
+    t_state = threading.Thread(
+        target=state_forward_loop,
+        args=(lowstate_sub, lowstate_sock, state_period),
+        daemon=True,
+    )
+    t_state.start()
+
+    # start action forwarding thread
+    t_cmd = threading.Thread(
+        target=cmd_forward_loop,
+        args=(lowcmd_sock, lowcmd_pub_debug, crc),
+        daemon=True,
+    )
+    t_cmd.start()
+
+    print("bridge running (lowstate -> zmq, lowcmd -> dds)")
+    # keep main thread alive so daemon threads don't exit
+    try:
+        while True:
+            time.sleep(1.0)
+    except KeyboardInterrupt:
+        print("shutting down bridge...")
+
+
+if __name__ == "__main__":
+    main()

src/lerobot/robots/unitree_g1/unitree_g1.py

@@ -0,0 +1,267 @@
+#!/usr/bin/env python
+
+# Copyright 2025 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# 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.
+
+import logging
+import struct
+import threading
+import time
+from dataclasses import dataclass, field
+from functools import cached_property
+from typing import Any
+
+import numpy as np
+from unitree_sdk2py.idl.default import unitree_hg_msg_dds__LowCmd_
+from unitree_sdk2py.idl.unitree_hg.msg.dds_ import (
+    LowCmd_ as hg_LowCmd,
+    LowState_ as hg_LowState,
+)
+from unitree_sdk2py.utils.crc import CRC
+
+from lerobot.robots.unitree_g1.g1_utils import G1_29_JointIndex
+from lerobot.robots.unitree_g1.unitree_sdk2_socket import (
+    ChannelFactoryInitialize,
+    ChannelPublisher,
+    ChannelSubscriber,
+)
+
+from ..robot import Robot
+from .config_unitree_g1 import UnitreeG1Config
+
+logger = logging.getLogger(__name__)
+
+# DDS topic names follow Unitree SDK naming conventions
+# ruff: noqa: N816
+kTopicLowCommand_Debug = "rt/lowcmd"
+kTopicLowState = "rt/lowstate"
+
+G1_29_Num_Motors = 35
+G1_23_Num_Motors = 35
+H1_2_Num_Motors = 35
+H1_Num_Motors = 20
+
+
+@dataclass
+class MotorState:
+    q: float | None = None  # position
+    dq: float | None = None  # velocity
+    tau_est: float | None = None  # estimated torque
+    temperature: float | None = None  # motor temperature
+
+
+@dataclass
+class IMUState:
+    quaternion: np.ndarray | None = None  # [w, x, y, z]
+    gyroscope: np.ndarray | None = None  # [x, y, z] angular velocity (rad/s)
+    accelerometer: np.ndarray | None = None  # [x, y, z] linear acceleration (m/s²)
+    rpy: np.ndarray | None = None  # [roll, pitch, yaw] (rad)
+    temperature: float | None = None  # IMU temperature
+
+
+# g1 observation class
+@dataclass
+class G1_29_LowState:  # noqa: N801
+    motor_state: list[MotorState] = field(
+        default_factory=lambda: [MotorState() for _ in range(G1_29_Num_Motors)]
+    )
+    imu_state: IMUState = field(default_factory=IMUState)
+    wireless_remote: Any = None  # Raw wireless remote data
+    mode_machine: int = 0  # Robot mode
+
+
+class DataBuffer:
+    def __init__(self):
+        self.data = None
+        self.lock = threading.Lock()
+
+    def get_data(self):
+        with self.lock:
+            return self.data
+
+    def set_data(self, data):
+        with self.lock:
+            self.data = data
+
+
+class UnitreeG1(Robot):
+    config_class = UnitreeG1Config
+    name = "unitree_g1"
+
+    # unitree remote controller
+    class RemoteController:
+        def __init__(self):
+            self.lx = 0
+            self.ly = 0
+            self.rx = 0
+            self.ry = 0
+            self.button = [0] * 16
+
+        def set(self, data):
+            # wireless_remote
+            keys = struct.unpack("H", data[2:4])[0]
+            for i in range(16):
+                self.button[i] = (keys & (1 << i)) >> i
+            self.lx = struct.unpack("f", data[4:8])[0]
+            self.rx = struct.unpack("f", data[8:12])[0]
+            self.ry = struct.unpack("f", data[12:16])[0]
+            self.ly = struct.unpack("f", data[20:24])[0]
+
+    def __init__(self, config: UnitreeG1Config):
+        super().__init__(config)
+
+        logger.info("Initialize UnitreeG1...")
+
+        self.config = config
+
+        self.control_dt = config.control_dt
+
+        # connect robot
+        self.connect()
+
+        # initialize direct motor control interface
+        self.lowcmd_publisher = ChannelPublisher(kTopicLowCommand_Debug, hg_LowCmd)
+        self.lowcmd_publisher.Init()
+        self.lowstate_subscriber = ChannelSubscriber(kTopicLowState, hg_LowState)
+        self.lowstate_subscriber.Init()
+        self.lowstate_buffer = DataBuffer()
+
+        # initialize subscribe thread to read robot state
+        self.subscribe_thread = threading.Thread(target=self._subscribe_motor_state)
+        self.subscribe_thread.daemon = True
+        self.subscribe_thread.start()
+
+        while not self.is_connected:
+            time.sleep(0.1)
+
+        # initialize hg's lowcmd msg
+        self.crc = CRC()
+        self.msg = unitree_hg_msg_dds__LowCmd_()
+        self.msg.mode_pr = 0
+
+        # Wait for first state message to arrive
+        lowstate = None
+        while lowstate is None:
+            lowstate = self.lowstate_buffer.get_data()
+            if lowstate is None:
+                time.sleep(0.01)
+            logger.warning("[UnitreeG1] Waiting for robot state...")
+        logger.warning("[UnitreeG1] Connected to robot.")
+        self.msg.mode_machine = lowstate.mode_machine
+
+        # initialize all motors with unified kp/kd from config
+        self.kp = np.array(config.kp, dtype=np.float32)
+        self.kd = np.array(config.kd, dtype=np.float32)
+
+        for id in G1_29_JointIndex:
+            self.msg.motor_cmd[id].mode = 1
+            self.msg.motor_cmd[id].kp = self.kp[id.value]
+            self.msg.motor_cmd[id].kd = self.kd[id.value]
+            self.msg.motor_cmd[id].q = lowstate.motor_state[id.value].q
+
+        # Initialize remote controller
+        self.remote_controller = self.RemoteController()
+
+    def _subscribe_motor_state(self):  # polls robot state @ 250Hz
+        while True:
+            start_time = time.time()
+            msg = self.lowstate_subscriber.Read()
+            if msg is not None:
+                lowstate = G1_29_LowState()
+
+                # Capture motor states
+                for id in range(G1_29_Num_Motors):
+                    lowstate.motor_state[id].q = msg.motor_state[id].q
+                    lowstate.motor_state[id].dq = msg.motor_state[id].dq
+                    lowstate.motor_state[id].tau_est = msg.motor_state[id].tau_est
+                    lowstate.motor_state[id].temperature = msg.motor_state[id].temperature
+
+                # Capture IMU state
+                lowstate.imu_state.quaternion = list(msg.imu_state.quaternion)
+                lowstate.imu_state.gyroscope = list(msg.imu_state.gyroscope)
+                lowstate.imu_state.accelerometer = list(msg.imu_state.accelerometer)
+                lowstate.imu_state.rpy = list(msg.imu_state.rpy)
+                lowstate.imu_state.temperature = msg.imu_state.temperature
+
+                # Capture wireless remote data
+                lowstate.wireless_remote = msg.wireless_remote
+
+                # Capture mode_machine
+                lowstate.mode_machine = msg.mode_machine
+
+                self.lowstate_buffer.set_data(lowstate)
+
+            current_time = time.time()
+            all_t_elapsed = current_time - start_time
+            sleep_time = max(0, (self.control_dt - all_t_elapsed))  # maintain constant control dt
+            time.sleep(sleep_time)
+
+    @cached_property
+    def action_features(self) -> dict[str, type]:
+        return {f"{G1_29_JointIndex(motor).name}.pos": float for motor in G1_29_JointIndex}
+
+    def calibrate(self) -> None:  # robot is already calibrated
+        pass
+
+    def configure(self) -> None:
+        pass
+
+    def connect(self, calibrate: bool = True) -> None:  # connect to DDS
+        ChannelFactoryInitialize(0)
+
+    def disconnect(self):
+        pass
+
+    def get_observation(self) -> dict[str, Any]:
+        return self.lowstate_buffer.get_data()
+
+    @property
+    def is_calibrated(self) -> bool:
+        return True
+
+    @property
+    def is_connected(self) -> bool:
+        return self.lowstate_buffer.get_data() is not None
+
+    @property
+    def _motors_ft(self) -> dict[str, type]:
+        return {f"{G1_29_JointIndex(motor).name}.pos": float for motor in G1_29_JointIndex}
+
+    @property
+    def _cameras_ft(self) -> dict[str, tuple]:
+        return {
+            cam: (self.config.cameras[cam].height, self.config.cameras[cam].width, 3) for cam in self.cameras
+        }
+
+    @cached_property
+    def observation_features(self) -> dict[str, type | tuple]:
+        return {**self._motors_ft, **self._cameras_ft}
+
+    def send_action(self, action: dict[str, Any]) -> dict[str, Any]:
+        self.msg.crc = self.crc.Crc(action)
+        self.lowcmd_publisher.Write(action)
+        return action
+
+    def get_gravity_orientation(self, quaternion):  # get gravity orientation from quaternion
+        """Get gravity orientation from quaternion."""
+        qw = quaternion[0]
+        qx = quaternion[1]
+        qy = quaternion[2]
+        qz = quaternion[3]
+
+        gravity_orientation = np.zeros(3)
+        gravity_orientation[0] = 2 * (-qz * qx + qw * qy)
+        gravity_orientation[1] = -2 * (qz * qy + qw * qx)
+        gravity_orientation[2] = 1 - 2 * (qw * qw + qz * qz)
+        return gravity_orientation

src/lerobot/robots/unitree_g1/unitree_sdk2_socket.py

@@ -0,0 +1,168 @@
+#!/usr/bin/env python
+
+# Copyright 2025 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# 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.
+
+import base64
+import json
+from typing import Any
+
+import zmq
+
+from lerobot.robots.unitree_g1.config_unitree_g1 import UnitreeG1Config
+
+_ctx: zmq.Context | None = None
+_lowcmd_sock: zmq.Socket | None = None
+_lowstate_sock: zmq.Socket | None = None
+
+LOWCMD_PORT = 6000
+LOWSTATE_PORT = 6001
+
+# DDS topic names follow Unitree SDK naming conventions
+# ruff: noqa: N816
+kTopicLowCommand_Debug = "rt/lowcmd"
+
+
+class LowStateMsg:
+    """
+    Wrapper class that mimics the Unitree SDK LowState_ message structure.
+
+    Reconstructs the message from deserialized JSON data to maintain
+    compatibility with existing code that expects SDK message objects.
+    """
+
+    class MotorState:
+        """Motor state data for a single joint."""
+
+        def __init__(self, data: dict[str, Any]) -> None:
+            self.q: float = data.get("q", 0.0)
+            self.dq: float = data.get("dq", 0.0)
+            self.tau_est: float = data.get("tau_est", 0.0)
+            self.temperature: float = data.get("temperature", 0.0)
+
+    class IMUState:
+        """IMU sensor data."""
+
+        def __init__(self, data: dict[str, Any]) -> None:
+            self.quaternion: list[float] = data.get("quaternion", [1.0, 0.0, 0.0, 0.0])
+            self.gyroscope: list[float] = data.get("gyroscope", [0.0, 0.0, 0.0])
+            self.accelerometer: list[float] = data.get("accelerometer", [0.0, 0.0, 0.0])
+            self.rpy: list[float] = data.get("rpy", [0.0, 0.0, 0.0])
+            self.temperature: float = data.get("temperature", 0.0)
+
+    def __init__(self, data: dict[str, Any]) -> None:
+        """Initialize from deserialized JSON data."""
+        self.motor_state = [self.MotorState(m) for m in data.get("motor_state", [])]
+        self.imu_state = self.IMUState(data.get("imu_state", {}))
+        # Decode base64-encoded wireless_remote bytes
+        wireless_b64 = data.get("wireless_remote", "")
+        self.wireless_remote: bytes = base64.b64decode(wireless_b64) if wireless_b64 else b""
+        self.mode_machine: int = data.get("mode_machine", 0)
+
+
+def lowcmd_to_dict(topic: str, msg: Any) -> dict[str, Any]:
+    """Convert LowCmd message to a JSON-serializable dictionary."""
+    motor_cmds = []
+    # Iterate over all motor commands in the message
+    for i in range(len(msg.motor_cmd)):
+        motor_cmds.append(
+            {
+                "mode": int(msg.motor_cmd[i].mode),
+                "q": float(msg.motor_cmd[i].q),
+                "dq": float(msg.motor_cmd[i].dq),
+                "kp": float(msg.motor_cmd[i].kp),
+                "kd": float(msg.motor_cmd[i].kd),
+                "tau": float(msg.motor_cmd[i].tau),
+            }
+        )
+
+    return {
+        "topic": topic,
+        "data": {
+            "mode_pr": int(msg.mode_pr),
+            "mode_machine": int(msg.mode_machine),
+            "motor_cmd": motor_cmds,
+        },
+    }
+
+
+def ChannelFactoryInitialize(*args: Any, **kwargs: Any) -> None:  # noqa: N802
+    """
+    Initialize ZMQ sockets for robot communication.
+
+    This function mimics the Unitree SDK's ChannelFactoryInitialize but uses
+    ZMQ sockets to connect to the robot server bridge instead of DDS.
+    """
+    global _ctx, _lowcmd_sock, _lowstate_sock
+
+    # read socket config
+    config = UnitreeG1Config()
+    robot_ip = config.robot_ip
+
+    ctx = zmq.Context.instance()
+    _ctx = ctx
+
+    # lowcmd: send robot commands
+    lowcmd_sock = ctx.socket(zmq.PUSH)
+    lowcmd_sock.setsockopt(zmq.CONFLATE, 1)  # keep only last message
+    lowcmd_sock.connect(f"tcp://{robot_ip}:{LOWCMD_PORT}")
+    _lowcmd_sock = lowcmd_sock
+
+    # lowstate: receive robot observations
+    lowstate_sock = ctx.socket(zmq.SUB)
+    lowstate_sock.setsockopt(zmq.CONFLATE, 1)  # keep only last message
+    lowstate_sock.connect(f"tcp://{robot_ip}:{LOWSTATE_PORT}")
+    lowstate_sock.setsockopt_string(zmq.SUBSCRIBE, "")
+    _lowstate_sock = lowstate_sock
+
+
+class ChannelPublisher:
+    """ZMQ-based publisher that sends commands to the robot server."""
+
+    def __init__(self, topic: str, msg_type: type) -> None:
+        self.topic = topic
+        self.msg_type = msg_type
+
+    def Init(self) -> None:  # noqa: N802
+        """Initialize the publisher (no-op for ZMQ)."""
+        pass
+
+    def Write(self, msg: Any) -> None:  # noqa: N802
+        """Serialize and send a command message to the robot."""
+        if _lowcmd_sock is None:
+            raise RuntimeError("ChannelFactoryInitialize must be called first")
+
+        payload = json.dumps(lowcmd_to_dict(self.topic, msg)).encode("utf-8")
+        _lowcmd_sock.send(payload)
+
+
+class ChannelSubscriber:
+    """ZMQ-based subscriber that receives state from the robot server."""
+
+    def __init__(self, topic: str, msg_type: type) -> None:
+        self.topic = topic
+        self.msg_type = msg_type
+
+    def Init(self) -> None:  # noqa: N802
+        """Initialize the subscriber (no-op for ZMQ)."""
+        pass
+
+    def Read(self) -> LowStateMsg:  # noqa: N802
+        """Receive and deserialize a state message from the robot."""
+        if _lowstate_sock is None:
+            raise RuntimeError("ChannelFactoryInitialize must be called first")
+
+        payload = _lowstate_sock.recv()
+        msg_dict = json.loads(payload.decode("utf-8"))
+        return LowStateMsg(msg_dict.get("data", {}))