Method and system for implementing boxing motion analysis

A system implementing boxing motion analysis, the system comprising an inertial measurement unit (IMU) placed on a wrist of a user and a computer device connected to the IMU, wherein the computer device is programmed to:

• obtain from the IMU plural entries of acceleration data at a plurality of time instances within a time period, each of the plural entries of acceleration data being with respect to one of three directions of a three-dimensional (3D) coordinate system;
• perform a dynamic adjustment operation on the plural entries of acceleration data, so as to obtain a number of entries of adjusted acceleration data, wherein the dynamic adjustment operation includes implementing matrix operations on the plural entries of acceleration data using the following equation
• A
• t
• O
• =
• [
• ⁠
• k
• x
• 0
• 0
• 0
• k
• y
• 0
• 0
• 0
• k
• z
• ⁠
• ]
• [
• ⁠
• 1
• -
• θ
• yz
• θ
• zy
• 0
• 1
• -
• θ
• zx
• 0
• 0
• 1
• ⁠
• ]
• ⁢
• (
• A
• t
• s
• -
• [
• b
• x
• 0
• 0
• 0
• b
• y
• 0
• 0
• 0
• b
• z
• ⁠
• ]
• )
• where
• A
• t
• O
• represents a set of three entries of adjusted acceleration data with respect to the three directions at the time instance t, kx, ky and kz represent three scale factors with respect to the three directions, respectively, θyz, θzy and θzx represent three inclination factors each with respect to two of the three directions, bx, by and by represent three deviation factors with respect to the three directions, respectively, and
• A
• t
• s
• represents a set of three entries of acceleration data with respect to the three directions at the time instance t;
• perform a signal cutting operation on the plural entries of acceleration data based on the number of entries of adjusted acceleration data, three average acceleration values corresponding respectively to the three directions when the IMU is in a stationary state, and three threshold values, so as to obtain a plurality of time segments, each of the time segments being associated with one swing motion and including three subsets of accelerations with respect to the three directions, respectively;
• and
• perform, with respect to each of the time segments, a quaternion calculation on the subsets of accelerations, so as to obtain plural entries of rotational acceleration data that correspond with the time instances within the time segment, respectively, performing a first integration operation on the plural entries of rotational acceleration data to obtain a plurality of velocities of the IMU over the time segment, performing a second integration operation on the plural entries of rotational acceleration data to obtain a plurality of locations of the IMU over the time segment, and obtaining a trajectory of the IMU in the time segment within the 3D coordinate system.