mHealth and Motion capturing.

Motion capture, or Mocap, is a technique for digitally recording movement. Are we playing games her? Originally used as an analysis tool for biomechanics, mocap is now successfully employed in a wide variety of sectors including mHealth related applications.

Movement is captured through the placement of sensors (or markers) on or near each joint of the body. As each joint moves the positions or angles between the markers are recorded. Software records the, angles, velocities, accelerations and impulses, providing an accurate digital representation of the movement.

Realtime data from mocap enables the diagnosis of problems or enhancement of performance in the arenas of biomechanics and sports. It can also assist in the design of products or buildings when applied to the field of engineering or ergonomics. Animazoo distinguishes three types of Mocap´s.

Gyroscopic systems use tiny inertial gyroscopes that are attached to a body. These directly record the rotations of the body parts. The rotational data is transmitted by radio to a receiver unit where it is mapped instantly to a skeleton in order that the data can be visualized in realtime. These systems perform with no lag in realtime, producing incredibly accurate data. The data retains nuance even with fast moves.

Mechanical systems track body joint angles directly and are often referred to as exo-skeleton mocap systems, due to the way the sensors are attached to the body. A person attaches the skeletal-like structure to their body and as they move so do the articulated mechanical parts, measuring the performer’s relative motion. Mechanical motion capture systems are realtime, relatively low-cost and usually wireless. Movement is captured through the placement of sensors (or markers) on or near each joint of the body. As each joint moves the positions or angles between the markers are recorded. Software records the, angles, velocities, accelerations and impulses, providing an accurate digital representation of the movement.

Optical systems triangulate the 3D position of a marker between one, two or more cameras that have been pre-calibrated for distance to provide overlapping projections. Tracking a large number of markers or multiple performers is accomplished by the adding more cameras. These systems can be expensive to buy, require technical expertise to operate and are studio based. They have a relatively small capture area and can suffer from occlusion as well as being complicated to set up. Magnetic and electrical interference makes these systems highly susceptible to error, they also require extensive data cleaning and technical expertise to operate plus they suffer from limited area of use and lag for realtime use.

Magnetic systems calculate position and orientation by measuring the relative magnetic flux of three orthogonal coils on both the transmitter and each receiver. Magnetic systems require only two-thirds the number of markers compared to optical systems. One drawback is that the markers are susceptible to magnetic and electrical interference from metal objects in the environment and electrical sources. Magnetic and electrical interference makes these systems highly susceptible to error, they also require extensive data cleaning and technical expertise to operate plus they suffer from limited area of use and lag for realtime use.