Abstract: A player calibrates the initial position and orientation of trajectory using their natural sports motion from a well-defined starting point. For example, a batter with mature swing mechanics maintains approximately the same bat orientation and position (“load configuration”) at the beginning of their swing. This load configuration is unique to that player and unlike that of other players and may represent the start of a swing (or other motion of interest) or may occur at any characteristic point in time during the motion. Subsequent motion data within the spatial frame can be accurately analyzed so that three-dimensional trajectory of the equipment or body segment can be precisely determined and presented in an animated playing environment on devices such as smartphones, tablets and laptops.

Abstract: A system and method for calibrating an inertial motion sensor attached to an article of sports equipment or to a body segment in accordance with the user's initial orientation and location at the beginning of a sports motion. The sensor captures real-time motion data and the calibrated initial orientation and location provide absolute heading angle and starting position of the equipment or body segment in a spatial frame. Subsequent motion data within the spatial frame can be accurately analyzed so that three dimensional trajectory of the equipment or body segment can be precisely determined and presented in an animated playing environment on devices such as smartphones, tablets and laptops.