iPi Biomech Add-on

Note: This article is under construction and will be published in a few days. Meanwhile refer to v2 documentation: http://wiki.ipisoft.com/Biomechanical_Analysis

Introduction

iPi Biomech Add-on is a convenient tool for in-depth biomechanical analysis of human motions. It includes visualization of tracking data and its export to various formats. It can be used for:

• Export of point cloud from multiple Kinect sensors for animation or research
• Gait analysis and rehabilitation
• Sports motion analysis
• Research in 3D human kinematics

Markerless tracking technology does not require clumsy suits, and work in real-life environments like regular office.

With iPi Biomech Add-on you can:

• Get Linear and Angular Quantities for selected joints, including
  • Linear coordinate, velocity, acceleration
  • Euler angles, angular velocity and angular acceleration
  • Quaternions and Rotation matrices
• Select convenient coordinate systems
  • Linear: Absolute (relative to floor), Relative to parent joint, Relative to center of mass
  • Angular: Absolute (relative to floor), Relative to parent joint
• Select Euler angles system
• Plot values of selected Quantities for selected bones
• Export joints motion data to file
  • Tab-separated text format (for Excel)
  • MATLAB format

• Export point clouds obtained from depth sensors to file
  • MATLAB, PCD, XYZ formats convenient for research
  • Krakatoa PRT, PLY, OBJ, Leika PTS formats convenient for animation

Note: iPi Biomech Add-on requires separate license key, which you need to activate in addition to iPi Mocap Studio license key. 30-days free trial provided.

Glossary

Linear quantities

Quantities derived from linear coordinate of the joint which connects bone to it's parent bone, including:

• Coordinate
• Velocity
• Acceleration

Angular quantities

Quantities derived from bones's Euler angle, including:

• Euler angle
• Angular velocity
• Angular acceleration
• Quaternions
• Rotation matrices

Linear coordinate system

Coordinate system used for linear quantities, can be:

• Absolute (relative to ground)
  • Axes are shown by selecting Move tool;
  • Y axis is vertical
  • XZ plane is floor
  • Center and X, Z axes directions are automatically set during calibration
  • Recenter Coordinates on Character button on Scene tab before tracking will align coordinate system with actor in T-pose
    • Y is vertical axis passing through center of mass
    • XZ plane is floor
    • X is directed along left arm in T-pose
• Relative to center of mass — axes are shown by selecting Move tool; center is in the actor model's center of mass
• Relative to parent joint — axes are shown by selecting Move tool; center coincides with the coordinates of the parent bone

Angular coordinate system

Coordinate system used for angular quantities, can be:

• Absolute (relative to ground) — in this system rotations are defined relative to ground
• Local (Relative to parent bone) — in this system rotations are defined relative to the parent bone

Euler angles system

Set of rotations which defines Euler angles, see here

Unit

Measurement unit of physical quantity