Figure 1. Joint markers in the bowstroke motion involving the bent-endpin (left) and the straight endpin (right). Joint markers were placed on the right shoulder, elbow, wrist, and finger.
The subject selected for the experiment was a 51 year old male. He stood at 1.9 meters and weighed 889 Newtons. The subject is a cello professor at the University of Michigan and has had extensive years of experience with the movement. He wore a black turtleneck and black dress slacks. Four joint markers were positioned on the right side of the body. They were placed on the acromion process, the lateral epicondyle of the humerus, the styloid process of the ulna, and the metacarpophalangeal joint.
|
|
|
|
Figure 1. Joint markers in the bowstroke motion involving the bent-endpin (left) and the straight endpin (right). Joint markers were placed on the right shoulder, elbow, wrist, and finger. |
|
The subject was videotaped in the Macintosh Theater at the University of Michigan. A Sony Hi8 camera was used at a speed set of 30 frames/s. Both trials taken of the subject were with the camera placed perpendicular to the frontal plane. The trials involved videotaping at a 45-degree angle. The modified angle provided a clearer view of the joint markers and eventually was chosen for the analysis. Overhead lighting from the stage was used. The subject was instructed to bow back and forth slowly on the third cello string. The lighting, speed of the bowstroke, and consistency of the bowstroke were all factors for considering which moves to analyze.
The images on the videotape were digitized at 30 frames/s using FusionRecorder on Macintosh computers in the New Media Center at the University of Michigan. Next, the specific video files were trimmed using MoviePlayer. The modified files were cut so only the frames between the start and end of the movements would be used. QT &endash;> PICT (custom utility) was then utilized in order to convert the QuickTime movie files into a selection of individual frames in PICT format. This primed the files for use with the Motion Plus software. The markers from the shoulder, elbow, wrist, and finger were digitized using Motion Capture. Coordinate data from the joint markers was exported in spreadsheet format to Excel for a biomechanical analysis using MotionAnalyse.