StepIt Sim 🤖

StepIt Sim is a framework for Sim-to-Sim validation, built upon stepit and unitree_mujoco. It provides a streamlined workflow for deploying policy networks in Robots.

🤖 Supported Robots

• Unitree G1
• Unitree Go2
• Unitree B2
• Unitree Aliengo

Note: Support for additional robotic platforms will be integrated in future updates.

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🏗️ Installation & Setup

1. Clone the Repository

git clone https://github.com/legnAray/stepit_sim.git
cd stepit_sim
git submodule update --init --recursive

2. Install System Dependencies

sudo apt update && sudo apt install -y cmake build-essential \
  libboost-dev libboost-filesystem-dev libboost-program-options-dev \
  libeigen3-dev libfmt-dev libyaml-cpp-dev \
  libspdlog-dev libglfw3-dev liblcm-dev

3. Install Unitree SDK2

git clone https://github.com/unitreerobotics/unitree_sdk2.git
cd unitree_sdk2 && mkdir build && cd build
cmake .. -DCMAKE_INSTALL_PREFIX=/opt/unitree_robotics
sudo make install

4. Link MuJoCo

Download MuJoCo 3.3.6 from MuJoCo Releases.

cd third_party/unitree_mujoco/simulate
ln -s ~/.mujoco/mujoco-3.3.6 mujoco

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🛠️ Build Instructions

Build unitree_mujoco

cmake -S third_party/unitree_mujoco/simulate \
      -B third_party/unitree_mujoco/simulate/build \
      -DCMAKE_BUILD_TYPE=Release
cmake --build third_party/unitree_mujoco/simulate/build -j

Build StepIt

export STEPIT_WHITELIST_PLUGINS="control_console;joystick_usb;joystick_udp;publisher_csv;policy_neuro;nnrt_onnxruntime;robot_unitree2"

cmake -S third_party/stepit -B build/stepit \
  -DSTEPIT_WHITELIST_PLUGINS="$STEPIT_WHITELIST_PLUGINS" \
  -DCMAKE_BUILD_TYPE=Release
cmake --build build/stepit -j

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🏃 Running Simulations

Basic Test

Launch the simulation and use the interactive console:

./scripts/run_sim.sh -r go2 -s scene.xml -c console -P dummy

Console examples: Agent/StandUp, Agent/LieDown

Policy Simulation

Simulate a learned policy with joystick control:

./scripts/run_sim.sh -r go2 -s scene.xml -c joystick -f joystick@usb -p path/to/policy_dir -P dummy

Template

Use the following template to launch the g1 simulation with the bundled example policy:

./scripts/run_sim.sh -r g1 -s scene.xml -c joystick -f joystick@usb -p ./template_policy/g1_amp -P dummy

Note for g1: The simulation includes a virtual elastic band for lifting and lowering the robot. Use keyboard 7 to lower the robot, 8 to lift it, and 9 to enable or release the suspension.

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🌐 ROS 2 Mode (Optional)

Enable StepIt’s ROS 2 interface for modular control.

1. Build ROS 2 Packages

source /opt/ros/<distro>/setup.zsh
cd ros2_ws
export STEPIT_WHITELIST_PLUGINS="control_console;joystick_usb;joystick_udp;publisher_csv;policy_neuro;nnrt_onnxruntime;robot_unitree2"
colcon build --base-paths src src/stepit/package/ros2 --packages-skip stepit --cmake-args \
  -DSTEPIT_WHITELIST_PLUGINS="$STEPIT_WHITELIST_PLUGINS;ros2_base" \
  -DCMAKE_BUILD_TYPE=Release

2. Launch in ROS 2 Mode

source ros2_ws/install/setup.zsh
./scripts/run_sim.sh -ros2 -r go2 -s scene.xml -c ros2_srv -P ros2 -f spin@ros2

3. Control Commands

Method	Command
Service	ros2 service call /control stepit_ros2_msgs/srv/Control "{request: 'Agent/StandUp'}"
Topic	ros2 topic pub --once /control std_msgs/msg/String "{data: 'Agent/StandUp'}"

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⚙️ Parameter Configuration

Refer to stepit for additional parameter details.

Argument	Description	Values
-ros2	Enable ROS 2 interface	(Flag)
-r	Robot model	aliengo, go2, b2, g1
-s	Scene XML file	scene.xml
-c	Controller type	console, joystick, ros2_msg, ros2_srv, dummy
-p	Policy directory path	/path/to/policy_dir
-P	Publisher type	dummy, csv, ros2
-f	default factory for a specified type	joystick@usb, spin@ros2, spin@wait_for_sigint
-v	Log level	0(Error), 1(Warn), 2(Info), 3(Debug)
--	Pass-through	Forward CLI args to StepIt plugins (e.g., ROS 2 args)

💡 Pass-through Examples

Use -- to pass arguments directly to StepIt plugins. This is particularly useful for ROS 2 node remapping or namespacing:

# Example: Passing ROS 2 arguments to set a namespace
./scripts/run_sim.sh -ros2 -r go2 -s scene.xml -c joystick -f joystick@usb -p path/to/policy_dir -P ros2 -- --ros-args -r __ns:=/go2

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🤝 Acknowledgements

This repository is built upon the following open-source projects:

• stepit
• unitree_mujoco