scikit-kinematics

scikit-kinematics primarily contains functions for working with 3D kinematics, e.g quaternions and rotation matrices. This includes utilities to read in data from the following IMU-sensors: - polulu - XSens - xio - xio-NGIMU - YEI

Compatible with Python >= 3.5

Dependencies

numpy, scipy, matplotlib, pandas, sympy, easygui

Homepage

http://work.thaslwanter.at/skinematics/html/

Author: Thomas Haslwanter Date: 11-07-2024 Ver: 0.9.3 Licence: BSD 2-Clause License (http://opensource.org/licenses/BSD-2-Clause) Copyright (c) 2024, Thomas Haslwanter All rights reserved.

Installation

You can install scikit-kinematics with

pip install scikit-kinematics

and upgrade to a new version with

pip install --upgrade --no-deps scikit-kinematics

IMUs

Analysis of signals from IMUs (intertial-measurement-units). Read in data, calculate orientation (with one of the algorithms below)

• get_data ... This method must be taken from one of the existing sensors, or from your own sensor. Currenlty the following sensors types are available:

  • XSens
  • xio (original, and NGIMU)
  • yei

  * polulu

• calc_position

MARG Systems

• imus.analytical ... Calculate orientation and position, from angular velocity and linear acceleration

• imus.kalman ... Calculate orientation from IMU-data using an Extended Kalman Filter.

• imus.IMU ... Class for working with data from IMUs

  : - imus.IMU.calc_position ... calculate position

  • imus.IMU.setData ... set the properties of an IMU-object
  • imus.IMU.set_qtype ... sets q_type, and automatically performs the relevant calculations.

• imus.Madgwick ... Class for calculating the 3D orientation with the Madgwick-algorithm

• imus.Mahony ... Class for calculating the 3D orientation with the Mahony-algorithm

Markers

Analysis of signals from video-based marker-recordings of 3D movements

• markers.analyze_3Dmarkers ... Kinematic analysis of video-basedrecordings of 3D markers
• markers.find_trajectory ... Calculation of joint-movements from 3D marker positions

Quaternions

Note that all these functions work with single quaternions and quaternion vectors, as well as with arrays containing these.

Quaternion class

• quat.Quaternion ... class, including overloading for multiplication and

  : division (e.g. "quatCombined = quat1 * quat2"), import and export

Functions for working with quaternions

• quat.q_conj ... Conjugate quaternion
• quat.q_inv ... Quaternion inversion
• quat.q_mult ... Quaternion multiplication
• quat.q_scalar ... Extract the scalar part from a quaternion
• quat.q_vector ... Extract the vector part from a quaternion
• quat.unit_q ... Extend a quaternion vector to a unit quaternion.

Conversion routines - quaternions --------------------------------=

• quat.calc_angvel ... Calculates the velocity in space from quaternions
• quat.calc_quat ... Calculate orientation from a starting orientation and angular velocity.
• quat.convert ... Convert quaternion to corresponding rotation matrix or Gibbs vector
• quat.deg2quat ... Convert number or axis angles to quaternion vectors
• quat.quat2seq ... Convert quaternions to sequention rotations ("nautical" angles, etc)
• quat.scale2deg ... Convert quaternion to corresponding axis angle

Rotation Matrices

Definition of rotation matrices ------------------------------=

• rotmat.R ... 3D rotation matrix for rotation about a coordinate axis

Conversion Routines - rotation matrices --------------------------------------=

• rotmat.convert ... Convert a rotation matrix to the corresponding quaternion
• rotmat.seq2quat ... Convert nautical angles etc. to quaternions
• rotmat.sequence ... Calculation of Euler, Fick, Helmholtz, ... angles

Symbolic matrices

• rotmat.R_s() ... symbolix matrix for rotation about a coordinate axis

For example, you can e.g. generate a Fick-matrix, with

>>> R_Fick = R_s(2, 'theta') * R_s(1, 'phi') * R_s(0, 'psi')

Spatial Transformation Matrices

• rotmat.stm ... spatial transformation matrix, for combined rotations/translations
• rotmat.stm_s() ... symbolix spatial transformation matrix

Denavit-Hartenberg Transformations

• rotmat.dh ... Denavit-Hartenberg transformation matrix
• rotmat.dh_s ... symbolic Denavit-Hartenberg transformation matrix

Vectors

Routines for working with vectors These routines can be used with vectors, as well as with matrices containing a vector in each row.

• vector.normalize ... Vector normalization
• vector.project ... Projection of one vector onto another one
• vector.GramSchmidt ... Gram-Schmidt orthogonalization of three points
• vector.q_shortest_rotation ... Quaternion indicating the shortest rotation from one vector into another.
• vector.rotate_vector ... Rotation of a vector
• vector.target2orient ... Convert target location into orientation angles

Interactive Data Analysis ========================-

• viewer.ts ... interactive viewer for time series data
• view.orientation ... visualize and animate orientations, expressed as quaternions.

Simulations

• simulate_movements ... calculated ideal IMU-signals for combined rotations/translations

Errata

The file Errata.pdf contains the a list of mistakes in the manuscript, and the corresponding corrections.