tubbz-alt / kinpy

Simple kinematics calculation toolkit for robotics

Simple kinematics body toolkit.

Core features

• Pure python library.
• Support URDF, SDF and MJCF file.
• Calculate FK, IK and jacobian.

Installation

pip install kinpy

Getting started

Here is a program that reads urdf and generates a kinematic chain.

import kinpy as kp

chain = kp.build_chain_from_urdf(open("kuka_iiwa/model.urdf").read())
print(chain)
# lbr_iiwa_link_0_frame
#  	lbr_iiwa_link_1_frame
#  	 	lbr_iiwa_link_2_frame
#  	 	 	lbr_iiwa_link_3_frame
#  	 	 	 	lbr_iiwa_link_4_frame
#  	 	 	 	 	lbr_iiwa_link_5_frame
#  	 	 	 	 	 	lbr_iiwa_link_6_frame
#  	 	 	 	 	 	 	lbr_iiwa_link_7_frame

Displays the parameter names of joint angles included in the chain.

print(chain.get_joint_parameter_names())
# ['lbr_iiwa_joint_1', 'lbr_iiwa_joint_2', 'lbr_iiwa_joint_3', 'lbr_iiwa_joint_4', 'lbr_iiwa_joint_5', 'lbr_iiwa_joint_6', 'lbr_iiwa_joint_7']

Given joint angle values, calculate forward kinematics.

import math
th = {'lbr_iiwa_joint_2': math.pi / 4.0, 'lbr_iiwa_joint_4': math.pi / 2.0}
ret = chain.forward_kinematics(th)

You can get the position and orientation of each link.

Visualization

KUKA IIWA

Mujoco humanoid

Mujoco ant

Simple arm

Citing

@software{kinpy,
    author = {{Kenta-Tanaka et al.}},
    title = {kinpy},
    url = {https://github.com/neka-nat/kinpy},
    version = {0.0.3},
    date = {2019-10-11},
}