Creating a C++ Extension

For performance-critical hardware drivers or integration with C++ libraries, you can create a C++ extension. This involves writing C++ code and exposing it to Python using pybind11.

Structure

A C++ extension typically looks like this:

rcs_mycppext/
├── CMakeLists.txt
├── pyproject.toml
├── src/
│   ├── MyDevice.cpp
│   ├── MyDevice.h
│   └── bindings.cpp
└── ...

Steps

1. CMake Configuration: Use CMakeLists.txt to configure your build. You’ll need to link against rcs (if it exposes C++ headers) and pybind11.

2. Implement C++ Class: Write your device driver in C++.

   #include <rcs/Robot.h>
   
   class MyRobot : public rcs::Robot {
   public:
       void setJointPosition(const Eigen::VectorXd& q) override {
           // ... implementation ...
       }
       // ... other methods ...
   };
   

3. Create Bindings: Use pybind11 to expose your class to Python.

   #include <pybind11/pybind11.h>
   #include "MyDevice.h"
   
   namespace py = pybind11;
   
   PYBIND11_MODULE(rcs_mycppext, m) {
       py::class_<MyRobot, rcs::Robot>(m, "MyRobot")
           .def(py::init<>())
           .def("set_joint_position", &MyRobot::setJointPosition);
   }
   

4. Build System: Use scikit-build or similar tools in pyproject.toml to compile the C++ extension during installation.

Examples

• rcs_fr3: Implements the driver for the Franka Research 3 robot in C++ using libfranka.

• rcs_robotics_library: Wraps the Robotics Library (RL) for kinematics and path planning.