Examples

While the majority of the kdFlex software is written in C++, Python bindings for the C++ classes are available as Python extensions. Example Python scripts, named notebook.py, are available within each of the subfolders within /usr/share/Karana/Tutorials in your local installation (/opt/homebrew/share/Karana/Tutorials if using macOS). These scripts illustrate the use of the kdFlex Python extension and can be run from within each of these folders by running python3 notebook.py.

There are also Jupyter notebook versions of each of the tutorials, named notebook.ipynb within the same folder. The introduction video shows how to run these notebooks from a remote machine, from a local machine, and as a normal Python script.

Python Tutorial Notebooks

This section contains tutorial examples on using kdFlex. The Python examples are included here, since the associated Jupyter notebooks can be converted to HTML. One can find these notebooks tutorials under /usr/share/Karana/Tutorials (/opt/homebrew/share/Karana/Tutorials if using macOS). The C++ examples cannot be easily converted to a web format, but are included with the kdflex package as well under /usr/share/Karana/Tutorials/example_cc (or /opt/homebrew/share/Karana/Tutorials/example_cc) if using macOS.

Jupyter notebook	Folder	Description/License tier	Video walkthrough
Importing a rover arm from a URDF file	example_urdf	Illustrates importing a Barrett WAM robot arm multibody model from a URDF file	Video Walkthrough
Importing M2020 rover model from a URDF file	example_m2020	Illustrates importing a Mars 2020 rover model from a URDF file
2 link pendulum (basic)	example_2_link_pendulum	Illustrates the step by step creation of the bodies for a 2-link pendulum, and setting up a time domain simulation for it.	Video Walkthrough
n link pendulum (procedural)	example_n_link_pendulum	Illustrates the procedural creation of an n-link pendulum and a time domain simulation for it.	Video Walkthrough
Spice frames (basic)	example_spice_frames	Illustrates use of the frames layer with planetary body frames
Import/export multibodies	example_import_export	Illustrates importing and exporting multibody models files in various formats; also, the use of units and quantities.
Visualization	example_visualization	Illustrates the capabilities of the 3D graphics layer.
Data logging	example_data_logging	Illustrates basic data logging capabilities.
Slider-crank with loop constraints	example_slider_crank	Illustrates creating a slide-crank system with loop constraints and graph topology.
Double wishbone	example_double_wishbone	Illustrates creating a double-wishbone system with loop constraints and graph topology.
2 link pendulum (collisions)	example_pendulum_collision	Illustrates collision dynamics with a 2-link pendulum example.
Multi-link procedural pendulum (collisions)	example_procedural_collision	Illustrates collision dynamics with a multi-link pendulum example.
Flexible slider-crank	example_flexible_slider_crank	Illustrates a slider-crank with a flexible body. This is a system that has both flexible bodies and closed loops.
Flexible double-wishbone	example_flexible_double_wishbone	Illustrates a double-wishbone with a flexible body. This is a system that has both flexible bodies and closed loops.
Rigid body SOA dynamics performance	example_rigid_timing	Verify O(N) performance of SOA dynamics by measuring computational time with varying number of bodies.
Rigid body SOA dynamics vs fully augmented performance	example_fully_augmented_benchmark	Compare O(N) performance of SOA dynamics with O(N^3) performance of conventional full-augmented (FA) dynamics.
Skid-steered driving	example_atrvjr_drive	Illustrates setting up and driving the ATRV-Jr, a simple skid-steered four wheel vehicle
Cart-pole reinforcement learning	example_cartpole	Integrates kdFlex with gymnasium to train on the classical cart-pole problem
Skid-steered reinforcement learning	example_atrvjr_learning	Integrates kdFlex with gymnasium to drive the ATRV-Jr (a skid-steered four wheel vehicle) to random goals
ROS2 integration	example_atrvjr_ros	Integrates kdFlex with ROS2 to monitor and command a vehicle

Each notebook has a corresponding notebook.py, which is a regular Python script.