The processing of the motion capture data

The collected data from the location of the markers were used to calculate three vectors. The first one was defined as the vector starting from the MCP joint of the Thumb and ending at the Thumb’s tip (VMT). The second vector started at the MCP joint of the Thumb and ended at the Index finger’s tip (VMI). The last vector started at the MCP joint of the Thumb and ended at the Middle finger’s tip (VMM). These vectors were used to calculate the angle between the Index finger and the Thumb (θTI), and the angle between the Middle finger and the Thumb (θTM). Figure ​Figure77 illustrates the angles. Formulas 1 and 2 show the calculation of each angle.

Considering the six wrist positions and three hand movements, the dataset included 18 different states (3 hand movements in 6 wrist positions) for θTI. As the Middle finger was not moving in Index Finger-Thumb grasp, the data from this movement was not included in the dataset of θTM. This provided 12 states (2 hand movements in 6 wrist positions) for the investigation of θTM.