scikit-kinematics 0.8.5

Python utilites for movements in 3d space

 — 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: 02-10-2020 Ver: 0.8.5 Licence: BSD 2-Clause License (<http://opensource.org/licenses/BSD-2-Clause>) Copyright (c) 2020, 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

&gt;&gt;&gt; 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.

## Errata The file [Errata.pdf](Errata.pdf) contains the a list of mistakes in the manuscript, and the corresponding corrections.