Kevin R. Campbell

Dynamics of children's gait

Abstract The purpose of the present study was to examine the characteristics of gait in 3- and 4-year-old children. Eighteen children completed 20 walking passes on each of two days. Sagittal plane kinematics and ground reaction force patterns were analyzed. From the kinematic data, high standard deviation values were noted for many of the segmental and angular velocity variables, especially the more distal segments and joints. Differences between boys and girls were observed in the linear and angular velocity values associated with the lower extremity. The ground reaction force patterns also displayed differences for the boys and girls with the boys exhibiting a greater difference in the vertical peak force values, a greater braking force, and a greater value for the medio-lateral force excursion measure. The results provide a comprehensive description of the gait characteristics of children and suggest that differences between boys and girls are evident at age 3 and 4.

The Use Of Videography For Three-Dimensional Motion Analysis

Special video path editing capabilities with custom hardware and software, have been developed for use in conjunction with existing video acquisition hardware and firmware. This system has simplified the task of quantifying the kinematics of human movement. A set of retro-reflective markers are secured to a subject performing a given task (i.e. walking, throwing, swinging a golf club, etc.). Multiple cameras, a video processor, and a computer work station collect video data while the task is performed. Software has been developed to edit video files, create centroid data, and identify marker paths. Multi-camera path files are combined to form a 3D path file using the DLT method of cinematography. A separate program converts the 3D path file into kinematic data by creating a set of local coordinate axes and performing a series of coordinate transformations from one local system to the next. The kinematic data is then displayed for appropriate review and/or comparison.

Quantitative Analysis Of Accuracy In The 3-D Video-Based Motion Analysis Corporation System

A complete system to quantify three-dimensional human movement kinematics was developed and initial accuracy testing was completed. This video-based system incorporates a video processor produced by Motion Analysis Corporation to edge-detect markers in a calibrated space, a SUN computer work station to receive data from the video processor, and appropriate software for analysis of the data. A series of tests was performed to compare static and dynamic accuracy of this video-based system to that reported of other video and film-based systems. The mean absolute errors for the static testing were 4.0 mm in the X direction, 2.5 mm in the Y direction, and 5.4 mm in the Z direction, with standard deviations of 4.0, 1.8, and 5.9 mm respectively. The mean absolute errors for the static testing were 11.1, 2.6, and 17.6 mm in the X, Y, and Z directions, respectively, with standard deviations of 0.4, 0.5, and 1.1 mm. These errors are comparable to those of other video-based systems but are slightly higher than those found with film-based systems.