Introduction

PND mujoco

pnd_mujoco is a simulator developed based on pnd_sdk_python and mujoco. Users can easily integrate the control programs developed with pnd_sdk_python and pnd_ros2 into this simulator, enabling a seamless transition from simulation to physical development. The repository with a structure as follows:

Directory Structure

• simulate_python: Simulator implemented based on pnd_sdk_python and mujoco
• pnd_robots: MJCF description files for robots supported by pnd_sdk_python
• example: Example programs

Supported pnd_sdk_python Messages:

Current version only supports low-level development, mainly used for sim to real verification of controller

• LowCmd: Motor control commands
• LowState: Motor state information
• SportModeState: Robot position and velocity data
• IMUState: Torso IMU state at rt/secondary_imu topic

Python Simulator Installation (simulate_python)

1. Install pnd_sdk_python

cd ~
sudo apt install python3-pip
git clone https://github.com/pndbotics/pnd_sdk_python.git
cd pnd_sdk_python
pip3 install -e .

2. Install MuJoCo Python

pip3 install mujoco==3.2.0

3. Install joystick support

pip3 install pygame

4. Test Simulation

cd simulate_python
python3 pnd_mujoco.py

Open another terminal:

python3 example/python/open_arm.py

The Adam‑U robot in simulation will lift and lower its arm.

Usage

Python Simulator Configuration

Configuration file: simulate_python/config.py

ROBOT = "adam_u" # Robot name, "adam_u", "adam_lite", "adam_pro" , "adam_sp"
ROBOT_SCENE = "../pnd_robots/" + ROBOT + "/scene.xml" # Robot scene
HANDPOSE_SRC = 1 # 0 is sim2sim 1 is real2sim
# For ROS2
# SDK_TYPE="ROS2" # "ROS2" or "DDS"
# DOMAIN_ID = 1 # Domain id

# For DDS
SDK_TYPE="DDS" # "ROS2" or "DDS"
DOMAIN_ID = 1 # Domain id

INTERFACE = "lo" # Interface 

USE_JOYSTICK = 1 # Simulate PND WirelessController using a gamepad
JOYSTICK_TYPE = "xbox" # support "xbox" and "switch" gamepad layout
JOYSTICK_DEVICE = 0 # Joystick number

PRINT_SCENE_INFORMATION = False # Print link, joint and sensors information of robot
ENABLE_ELASTIC_BAND = True # Virtual spring band, used for lifting adam

SIMULATE_DT = 0.001  # Need to be larger than the runtime of viewer.sync()
VIEWER_DT = 0.01  # 100 fps for viewer

Humanoid Virtual Hoist

To simulate the suspension & release process of humanoid robots:

• Enable in config:

ENABLE_ELASTIC_BAND = 1

• Controls:
  • 9 — engage/release hoist
  • 7 — lower robot
  • 8 — lift robot

Sim to Real

The example folder contains simple examples of using different interfaces to make the robot stand up and then lie down. These examples demonstrate how to implement the transition from simulation to reality using interfaces provided by PND. Here is an explanation of each folder name:

Folder	Description
python	Python examples using pnd_sdk_python
ros2	ROS2 examples using pnd_ros2

pnd_sdk_python

1. Install

# Install system dependencies
sudo apt install libyaml-cpp-dev libspdlog-dev libboost-all-dev libglfw3-dev python3-pip

# Install Python SDK
cd ~
git clone https://github.com/pndbotics/pnd_sdk_python.git
cd pnd_sdk_python
sudo pip3 install -e .

2. Run

cd ~/pnd_sdk_python/example/low_level/adam_lite
python3 adam_lite_low_level_example.py  enp59s0

pnd_ros2

1. Source

# Download & build pnd_ros2
git clone https://github.com/pndbotics/pnd_ros2.git
cd pnd_ros2
colcon build
source install/setup.bash

2. Modify config.py

DDS is used by default. To switch to ROS2: Open the configuration file config.py

cd ~
xdg-open ~/pnd_mujoco/simulate_python/config.py

Set the SDK type to ROS2:

SDK_TYPE="ROS2"

3. Run

cd ~/pnd_sdk_python/example/low_level/adam_lite # Robot name, "adam_u", "adam_lite", "adam_pro" , "adam_sp"
python3 adam_lite_low_level_example.py  enp59s0 # Robot name, "adam_u", "adam_lite", "adam_pro" , "adam_sp", replace enp59s0 with the actual wired network interface name

pnd_sdk_cpp

1. Install

To build your own application with the SDK, you can install the pnd_sdk_cpp to your system directory:

cd ~/pnd_sdk_cpp
mkdir build
cd build
cmake .. 
sudo make install

Or install pnd_sdk_cpp to a specified directory:

cd ~/pnd_sdk_cpp
mkdir build
cd build
cmake .. -DCMAKE_INSTALL_PREFIX=/opt/pndbotics_robotics
sudo make install

Important

If you install to a non-standard path, remember to add that path to your ${CMAKE_PREFIX_PATH} so that find_package() can locate the SDK in your own projects.

2. Run Example

• Run on real robot:

# Get network interface name
ip a

# Run the control example (replace enp59s0 with the wired network interface name)
cd ~/pnd_sdk_cpp/build/bin
sudo ./lite_ankle_swing_example enp3s0

Python Example: Sim vs Real

python3 ./open_arm.py           # simulation
python3 ./open_arm.py enp3s0    # real robot (network interface)

Program logic:

if len(sys.argv) < 2:
    ChannelFactoryInitialize(1, "lo")   # simulation
else:
    ChannelFactoryInitialize(1, sys.argv[1])   # real robot

Supported PND SDK Messages

• LowCmd — motor control command
• LowState — motor state feedback

Message (DDS IDL) Type

The PND Adam-U robot model uses the adam_u idl for low-level communication.

📄 License

BSD-3 Clause © PNDbotics

📖 Reference

• pnd_sdk_python
  • pnd_ros2
  • PND wiki
• mujoco doc

🙏 Acknowledgement

• MuJoCo physics engine
• ROS2 community
• DDS community
• PNDbotics SDK ecosystem

📞 Contact

• Email: info@pndbotics.com
• Wiki: https://wiki.pndbotics.com
• SDK: https://github.com/pndbotics/pnd_sdk_python
• Issues: https://github.com/pndbotics/pnd_mujoco/issues

📜 Version Log

Version	Date	Updates
v1.3.1	2026-04-20	Fix gripper bug
v1.3.0	2026-04-02	Add adam_pro with gripper
v1.2.0	2026-01-22	DDS refactoring version
v1.0.4	2025-12-09	Update xbox axis & Add lo ro home in switch
v1.0.3	2025-11-20	Get state in ros2
v1.0.2	2025-11-17	Change the meshes and add Columns mass to 88 kg
v1.0.1	2025-11-11	Add ros2 example & Support hands
v1.0.0	2025-11-10	Initial release

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