From Traditional Three Pillar Monitoring Concept To Novel Four Pillar Monitoring Concept
Today's continuous vital signs monitoring is based on what we call at STBL "Three Pillar Monitoring Concept". The first pillar (1) represents the capture of prime signal capturing. The second pillar (2) stands for capturing of surrounding/environmental factors (artefacts/noises). The third pillar (3) stands for measuring the influences of motions/dynamics.
The critical point of this concept is motion/dynamics. Motion and dynamics captured by current sensor techonology (e.g. accelerometer and others) are based on or make use of classical mechanics concepts including the Euclidean/Cartesian spaces.
The linear relocation of a rigid body from point A to point B in a three dimensional space is usually captured. Therefore, the reference is implicitly or explicitly to a relative movement or position in an imaginary room or box. Vectors are generally calculated while the object moves. In an Euclidean 3D-space or Cartesian coordinate system, all movements can be represented in context to a 3D framework (xyz axis). Even complex swim movements can be captured with such technology, as long as all conditions are fullfilled such as the numbers of Degrees of Freedom (DoF) are known.
In classical mechanics, the position and orientation of a rigid body in space is defined by three components of translation and three components of rotation, which means that it has six degrees of freedom.
When it comes to human vital signs monitoring, vector physics does not explain it all. Humans are not rigid bodies but soft bodies. While the skeleton gives the body its structural shape, humans consists of at least 50% of water. As muscles and tendons (soft part) far exceeds the number of bones (rigid part) there is an infinite number of degrees of freedom (DoF) observable. As a result, Soft Body Dynamics, dynamics/deformations on the surface of the skin, micro and slow motions are hardly recognizable by traditional monitoring and therefore impossible to describe in terms of an Euclidean/Cartesian 3D-framework.
Soft Body Dynamics is a term coined by the motion pictures and computer animations industries around 1985. SBD summarizes the complex properties and behaviour of deformable objects (soft bodies) such as the change of shape in motion and its realistic emulation/simulation - exactly what a human being would describe. However, till to date Soft Body Dynamics is hardly ever spoken of explicitily when it comes to smart wearables, medical, health or fitness tracking devices
In STBL's view, in order to capture motions/dynamics/deformations correctly, the methodological concept must be expanded. Motions has to be split into 3D-Motions (linear, vector based) and Soft Body Dynamics (e.g. deformations etc.).The result of this becomes "Four Pillar Monitoring Concept".