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A six-accelerometer inertial tracking package currently in intensive use in measuring living human and human surrogate response to impact acceleration is presented and discussed. The discussion includes an enumeration of the various requirements imposed upon the package as well as its design and fabrication. The on-site calibration facility is described, including a discussion of the procedures for routine calibration of the packages. Accounts of the data acquisition link from the packages through the sled borne amplifiers to the hybrid computer are also included. Particular attention is devoted to the theoretical aspects of this system. A statement of errors is developed and compared to the various precision parameters of this system and to a general estimation of the dynamic response envelope demonstrating the overall feasibility of this approach.

In preparation of an analog of human head and neck, the reports by R. G. Snyder and others were noted which stated that initial position of the head and neck had a definite effect upon resulting response. An investigation was undertaken to attempt to quantitate this effect, as a part of a much larger study underway for several years. Thirteen human volunteer subjects ranging from the 5th to the 97th percentile in sitting height were exposed to -Gx impact acceleration at peak sled accelerations of 6G and 10G. Two angles of the neck relative to chair and two angles of the head relative to the neck for a total of four conditions were tested for each subject for the 2 peak acceleration levels giving a total of 104 experiments. Instrumentation consisted of 6 accelerometers and two-axis rate gyro at the posterior spinous process of the first thoracic vertebral body, 6 accelerometers at the mouth, and a two-axis rate gyro at the top of the head.