orsoromeo/jet-leg

This is an open-source python package that shows how to compute the Feasible Region, i.e. the extension of the well known support region to include joint-torque limits constraints. The details are explained in this preprint:

Feasible Region: an Actuation-Aware Extension of the Support Region

This python library contains the code used for the motion planning formulation proposed in this preprint. In here you can also find the code used to generate the figures and plots of the manuscript.

Jet-leg performs common operations over convex polyhedra in higher dimensions in order to assess the problem of stability and motion feasibility of legged robots.

What you can do with Jet-leg:

• compute the Support region of legged robots as in Bretl. et al. 2008;
• compute the Feasible region of legged robots as in Orsolino. et al. 2019;
• compute force polytopes of legged robots given their URDF;
• compare different leg designs and understand their consequences on the robot's balancing capabilities;
• test various formulations of linear, convex or nonlinear trajectory optimization problems;

Dependencies

APT dependencies:

• CVXOPT
• GLPK
• Cython

ROS dependencies:

sudo apt-get  install ros-kinetic-graph-msgs

Python dependencies:

• Numpy
• Scipy
• Pycddlib
• Matplotlib
• Pypoman for the manipulation of polyhedrical object
• Pinocchio

The above dependencies can be installed with the following commands:

sudo apt-get install cython libglpk-dev python python-dev python-pip python-scipy
CVXOPT_BUILD_GLPK=1 pip install cvxopt --user
pip install pycddlib --user
pip install pypoman

You can remove all --user arguments to install these Python modules system-wide.

Optional dependencies:

• Ipopt and its Python interface Pypi for the solution of large-scale nonlinear optimization problems
• ffmpeg for the generation of Matplotlib animations

sudo apt-get install ffmpeg

• unittest for testing of dependencies installation and for development

Testing the library

After completing the installation navigate to the examples folder:

• single_iterative_projection_example.py can be used to see how to set up an iterative projection problem in order to compute the friction/actuation/feasible region;
• check_stability_lp_example.py can be used to quickly check whether the given robot configuration is statically stable or not (without explicitly computing the feasible region);
• plotIPstatistics.py can be used to generate some statistics about the computation time of the IP algorithm for random feet positions (see Fig. 6 of the preprint);
• plotInstantaneousActuationRegionVariableMass.py can be used to generate a plot that shows how the feasible regions can changes depending on the gravitational force acting on the robot's center of mass (see Fig. 8 of the preprint)

Troubleshooting

• if CVXOPT is not found even after trying the pip-installation, we then suggest to try install the version 1.1.4 of CVXOPT using Synaptic or to clone and install it manually after building.
• IMPORTANTE NOTE: delete every previous installation of cvxopt that is in the system using locate cvxopt (after sudo updatedb)

See also

• The pypoman and pymanoid libraries developed by Stéphane Caron
• Komei Fukuda's Frequently Asked Questions in Polyhedral Computation
• The Polyhedron class in Sage
• The StabiliPy package provides a more general recursive projection method

jet-leg's Issues

Unittest and examples fail

Hi,
Running the unittest fails for a number reasons:
a) inverse_kin() takes exactly 3 arguments (7 given)
b) LP_projection() takes at most 6 arguments (10 given)
c) getInequalities() takes at most 3 arguments (10 given)

The example I am interested in is the actuation_region_main.py and actuation_region_example.py as I was planning to use these as the starting point to understand how I can integrate the code for my use case.

Running actuation_region_example.py result in the following error:

AttributeError: IterativeProjectionParameters instance has no attribute 'getCoMPos'
The class instead has getCoMPosWF and getCoMPosBF

Running actuation_region_main.py result in the following error:

iterative_projection_bretl() takes at most 3 arguments (7 given)

Could these two examples and necessary functions be updated? Alternatively, which example is more updated that I should use?