ultrainren / urdf2casadi

Python library for getting a casadi function for the forward kinematics of a URDF chain

URDF2CASADI

A module for generating the forward kinematics of a robot from a URDF. It can generate the forward kinematics represented as a dual quaternion or a transformation matrix. urdf2casadi works both in python 2 and 3, and any platform that supports CasADi and urdf_parser_py.

Installation

With ROS:

1. Get ROS (actually anything that installs urdfdom_py/urdf_parser_py will do).
2. Get CasADi (e.g. pip install casadi).
3. Run pip install --user . in the folder.

Without ROS:

1. Change the urdfdom-py to urdf-parser-py in requirements.txt (line 3) and in setup.py (line 20).
2. Get CasADi (e.g. pip3 install casadi).
3. Run pip3 install --user . in the folder (--user specifies that it is a local install).

Usage example

import casadi as cs
from urdf2casadi import converter
fk_dict = converter.from_file("root", "gantry_tool0", "robot_urdf_file_path.urdf")
print fk_dict.keys()
# should give ['q', 'upper', 'lower', 'dual_quaternion_fk', 'joint_names', 'T_fk', 'joint_list', 'quaternion_fk']
forward_kinematics = fk_dict["T_fk"]
print forward_kinematics([0.3, 0.3, 0.3, 0., 0.3, 0.7])

Todo/Implementation status

• Forward kinematics with SE(3) matrix
• Forward kinematics of rotation with quaternion
• Dual Quaternions as alternative to SE(3) matrices
• Dynamics from links and their inertia tags
• Denavit Hartenberg?
• unit tests
• Examples