Dynamic wrist motion analysis using six degree of freedom sensors

Dynamic motion analysis of the wrist in the past has been a tedious and often impossible task to undertake. However, such motion analysis is now practical with the use of the McDonnell Douglas 3Space Digitizer and Macintosh microcomputer. The feasibility of using this system with multiple electromagnetic sensors for upper extremity kinematics analysis has been previously described by our laboratory. This work has now been extended to the dynamic analysis of wrist motion during performance of a work task by placing one sensor on the hand and the other on the distal forearm. The 3Space Digitizer source creates a low-frequency magnetic field. Sensors placed within the field have a specific position and orientation with respect to a coordinate system defined by the source. The x, y, z coordinates and theta, phi, psi orientation angles of the sensors on the subject's extremity are measured during task performance at a rate of approximately 19 readings per second. Analysis of this data provides a "motion signature" of the task under study. After the task completion the data obtained from the digitizer (orientation of the hand and forearm with respect to the digitizer's source) is stored on a computer disk and then reduced using mathematical transformations to obtain instantaneous radial/ulnar deviation (RUD), flexion/extension (FE), and supination/pronation (SP). The transformed data is displayed graphically as RUD vs. time, or FE vs. time and SP vs. time for each given task. A frequency analysis for each task performed is obtained with the use of the Macintosh microcomputer and a Fast Fourier Transform.(ABSTRACT TRUNCATED AT 250 WORDS)