Repository files navigation

This folder contains python wrappers around RaiSim (raisimLib andraisimOgre) usingpybind11.

Small parts of the wrappers were inspired by the code given in theraisimGym/raisim_gym/env/ folder.If you use these wrappers, please acknowledge their contribution as well by citing [1-4].

The following wrappers have been tested on Ubuntu 16.04 with Python 3.5 and 2.7. Other platforms and Pythonversions might work as well but we didn't test them yet.

In order to use the wrappers, you will have to install at leastraisimLib andraisimOgre. You will also have to installpybind11 as we use this to wrap the C++ code.

If you followed the installation procedure ofraisimLib and/orraisimOgre, you will have the two followingenvironment variables defined:

• WORKSPACE: workspace where you clone your git repos (e.g., ~/raisim_workspace)
• LOCAL_BUILD: build directory where you install exported cmake libraries (e.g., ~/raisim_build)

First, clone this repository:

cd$WORKSPACEgit clone https://github.com/robotlearn/raisimpycd raisimpy

Then, compile the python wrappers from theraisimpy folder by typing:

mkdir build&&cd buildcmake -DPYBIND11_PYTHON_VERSION=$PYTHON_VERSION -DCMAKE_PREFIX_PATH=$LOCAL_BUILD -DCMAKE_INSTALL_PREFIX=$LOCAL_BUILD ..make -j4make install

where$PYTHON_VERSION is the Python version you wish to use (e.g.PYTHON_VERSION=3.5).

Now, you just need toexport PYTHONPATH=$PYTHONPATH:$LOCAL_BUILD/lib to be able to access the python library. You canadd thisexport line in yourbashrc.

Once it has been compiled, you can access to the Python libraryraisimpy in your code with:

importraisimpyasraisimprint(dir(raisim))

We mostly follow the naming convention defined inraisimLib andraisimOgre, however we follow the PEP8 guideline.Thus, a C++ method like:

getComPosition()

becomes

get_com_position()

Note that in the originalraisimLib, the authors sometimes use their own defined data types for vectors andmatrices (such asVec<n>,Mat<n,m>,VecDyn,MatDyn, etc). The Ogre library used for thevisualization also uses its own defined data types (such asVector3,Matrix3,Quaternion, etc).When usingraisimpy, these datatypes are automatically converted (back and forth) to numpy arrays as thisis the standard in Python. We also follow the convention that if an attribute is a python list or std::vector,we add the suffix 's' at the end of the attribute, and we write the full name of the variables (i.e. withoutusing diminutives), such as:

Body b;std::vector<Shape::Type> shapes = b.colshape;

in C++, becomes in Python:

b=Body()shapes=b.collision_shapes# no diminutives (colshape --> collision_shape), and added the 's' suffix to specify it is a list.

The code has been documented, so you can always see it usinghelp or?, for instance:

importraisimpyasraisimworld=raisim.World()world.add_sphere?# orhelp(world.add_sphere)

Here is the C++ example that was provided in the README in [2]:

#include"raisim/World.hpp"intmain() {    raisim::World world;auto anymal = world.addArticulatedSystem("pathToURDF");// initialized to zero angles and identity orientation. Use setState() for a specific initial conditionauto ball = world.addSphere(1,1);// radius and massauto ground = world.addGround();    world.setTimeStep(0.002);    world.integrate();}

This becomes in Python:

importraisimpyasraisimworld=raisim.World()anymal=world.add_articulated_system("path_to_urdf")ball=world.add_sphere(radius=1,mass=1)ground=world.add_ground()world.set_time_step(0.002)world.integrate()

Other examples can be found in theexamples folder, which are the sames as the ones that you can find in theexamples folders inraisimLib [2],raisimOgre [3], andraisimGym [4]. I will add the other examplesas soon as I have the time.

• [1] "Per-contact iteration method for solving contact dynamics", Hwangbo et al., 2018
• [2] raisimLib:https://github.com/leggedrobotics/raisimLib
• [3] raisimOgre:https://github.com/leggedrobotics/raisimOgre
• [4] raisimGym:https://github.com/leggedrobotics/raisimGym
• [5] pybind11:https://pybind11.readthedocs.io/en/stable/

• fatal error: Eigen/*: No such file or directory

  • If you have Eigen3 installed on your system, you probably have to replace all the#include <Eigen/*> by#include <eigen3/Eigen/*>. You can create symlinks to solve this issue:

  cd /usr/local/includesudo ln -sf eigen3/Eigen Eigensudo ln -sf eigen3/unsupported unsupported

  or you can replace the#include <Eigen/*> by#include <eigen3/Eigen/*>.

• Segmentation fault. This is probably an oversight on my part, the error is probably due to some poor managementof pointers and memory allocation. E.g. an object has been deleted from the Python side but the C++ side is alsotrying to delete it. Just open an issue on Github, and I will fix it as soon as I can. If you fixed it, you cansubmit a pull request.

• Error about adress mapping while running RL examples, like the following one:

  Signal: Segmentation fault (11)Signal code: Address not mapped (1)Failing at address: xxxxx

  this seems to be caused by TensorFlow, but I have to investigate deeper what causes that error.

The following software is distributed under theMIT License,however the RaiSim software is under the End-User License Agreement that you can findhere.

If the code presented here was useful to you, we would appreciate if you could cite the original authors:

@article{hwangbo2018per,    title={Per-contact iteration method for solving contact dynamics},    author={Hwangbo, Jemin and Lee, Joonho and Hutter, Marco},    journal={IEEE Robotics and Automation Letters},    volume={3},    number={2},    pages={895--902},    year={2018},    publisher={IEEE}}

If you still have some space in your paper for the references, you can add the following citation:

@misc{delhaisse2019raisimpy    author = {Delhaisse, Brian and Rozo, Leonel},    title = {RaiSimPy: A Python wrapper for RaiSim},    howpublished = {\url{https://github.com/robotlearn/raisimpy}},    year=2019,    }

Otherwise, you can just add me in the acknowledgements ;)

If you useraisimpy through thepyrobolearn framework (this is anongoing work), you can cite this last one instead (but you still have to cite the authors of RaiSim).