Human Kinematics

Human Kinematics was developed to compute segment and joint angles of the lower extremities of the body as well as trunk angle, but also to display a human model in real-time.

Algorithms were generated to gain kinematic data from the MTw Development Kit system of the company Xsens Technologies B. V. Hereby the sensor positioning was first estimated, and then the rotation around the vertical axis was removed due to drifts of the yaw angle. The drift is mainly caused by ferromagnetic materials in the prosthetics as well as by components of another measurement system. Conducted experiments showed that 5 cm distance between one MTw unit and the disturbance source reduces substantially the perturbance of the recorded magnetic field. However a greater distance is recommended. (Xsens: another option is to use the Xsens Magnetic Field Mapper, which is part of the MTw SDK, to cancel out a constant perturbance of the magnetic field. This will result in a stable and accurate yaw angle output). The human model was developed using corrected rotation matrices and translation vectors which define the distances between the joints of the model. The vertical positions for both thigh sensors and sacral sensor were computed and then implemented in the human kinematic chain for a very close to reality model. In the virtual 3D space the floor was used as geometric constraint, so that during gait the foot does not go under the floor. The computation algorithms as well as the human model were then integrated in the Human Kinematics software, which has the following features:
  • Open data;
  • Compute valid orientation data;
  • Save data;
  • Display human model in four speed settings, from real-time to 25% of the real-time speed;
  • Five standard viewing angles and one custom setting. The custom setting allows the user to choose the desired viewing angle;
  • Slider function to jump forwards or backwards in the data;
  • Freeze the human model in order to analyze a certain posture of the human body;
  • Stop and exit function in order to stop the motion and exit the software.