Measurement of six degrees of freedom head kinematics in impact conditions employing six accelerometers and three angular rate sensors (6aω configuration).

The ability to measure six degrees of freedom (6 DOF) head kinematics in motor vehicle crash conditions is important for assessing head-neck loads as well as brain injuries. A method for obtaining accurate 6 DOF head kinematics in short duration impact conditions is proposed and validated in this study. The proposed methodology utilizes six accelerometers and three angular rate sensors (6aω configuration) such that an algebraic equation is used to determine angular acceleration with respect to the body-fixed coordinate system, and angular velocity is measured directly rather than numerically integrating the angular acceleration. Head impact tests to validate the method were conducted using the internal nine accelerometer head of the Hybrid III dummy and the proposed 6aω scheme in both low (2.3 m/s) and high (4.0 m/s) speed impact conditions. The 6aω method was compared with a nine accelerometer array sensor package (NAP) as well as a configuration of three accelerometers and three angular rate sensors (3aω), both of which have been commonly used to measure 6 DOF kinematics of the head for assessment of brain and neck injuries. The ability of each of the three methods (6aω, 3aω, and NAP) to accurately measure 6 DOF head kinematics was quantified by calculating the normalized root mean squared deviation (NRMSD), which provides an average percent error over time. Results from the head impact tests indicate that the proposed 6aω scheme is capable of producing angular accelerations and linear accelerations transformed to a remote location that are comparable to that determined from the NAP scheme in both low and high speed impact conditions. The 3aω scheme was found to be unable to provide accurate angular accelerations or linear accelerations transformed to a remote location in the high speed head impact condition due to the required numerical differentiation. Both the 6aω and 3aω schemes were capable of measuring accurate angular displacement while the NAP instrumentation was unable to produce accurate angular displacement due to double numerical integration. The proposed 6aω scheme appears to be capable of measuring accurate 6 DOF kinematics of the head in any severity of impact conditions.

[1]  S. Tashman,et al.  Kinematics of human cadaver cervical spine during low speed rear-end impacts. , 2000, Stapp car crash journal.

[2]  Dimitrios Kallieris,et al.  Cervical human spine loads during traumatomechanical investigations , 1997 .

[3]  Guy S. Nusholtz,et al.  Using Triaxial Angular Rate Sensor and Accelerometer to Determine Spatial Orientation and Position in Impact Tests , 2009 .

[4]  M. Schlick,et al.  Biomechanics of human occupants in simulated rear crashes: documentation of neck injuries and comparison of injury criteria. , 2000, Stapp car crash journal.

[5]  Guy S. Nusholtz,et al.  Geometric methods in determining rigid-body dynamics , 1993 .

[6]  Parviz E. Nikravesh,et al.  Euler Parameters in Computational Kinematics and Dynamics. Part 1 , 1985 .

[7]  John W. Melvin,et al.  MEASUREMENT OF HEAD DYNAMICS AND FACIAL CONTACT FORCES IN THE HYBRID III DUMMY , 1986 .

[8]  Jeffrey Richard Crandall,et al.  Measurement Techniques for Angular Velocity and Acceleration in an impact Environment , 1997 .

[9]  F. Dimasi,et al.  TRANSFORMATION OF NINE-ACCELEROMETER-PACKAGE (NAP) DATA FOR REPLICATING HEADPART KINEMATICS AND DYNAMIC LOADING. , 1995 .

[10]  Claude Tarriere,et al.  Measurement of head angular acceleration in crash tests: development of an electronic device for the Hybrid III dummy , 1992 .

[11]  Rolf H Eppinger,et al.  On the Development of the SIMon Finite Element Head Model. , 2003, Stapp car crash journal.

[12]  E. Becker,et al.  An Experimentally Validated 3-D Inertial Tracking Package for Application in Biodynamic Research , 1975 .

[13]  Guy S. Nusholtz,et al.  Critical Limitations on Significant Factors in Head Injury Research , 1986 .

[14]  Scott Tashman,et al.  A study of the response of the human cadaver head to impact. , 2007, Stapp car crash journal.

[15]  G. C. Willems,et al.  The effect of the initial position of the head and neck on the dynamic response of the human head and neck to -Gx impact acceleration , 1975 .

[16]  Y King Liu,et al.  Lightweight low-profile nine-accelerometer package to obtain head angular accelerations in short-duration impacts. , 2006, Journal of biomechanics.

[17]  G. C. Willems,et al.  Dynamic response of the human head and neck to +Gy impact acceleration , 1977 .

[18]  Rolf H. Eppinger,et al.  COMPUTATIONAL ANALYSIS OF HEAD IMPACT RESPONSE UNDER CAR CRASH LOADINGS , 1995 .

[19]  Albert I. King,et al.  FULL-SCALE EXPERIMENTAL SIMULATION OF PEDESTRIAN-VEHICLE IMPACTS , 1976 .

[20]  Christophe Brigout,et al.  Computation of Hybrid III head dynamics in various impact situations , 1990 .

[21]  A. King,et al.  Measurement of Angular Acceleration of a Rigid Body Using Linear Accelerometers , 1975 .

[22]  Darren R. Laughlin,et al.  A Magnetohydrodynamic Angular Motion Sensor for Anthropomorphic Test Device Instrumentation , 1989 .

[23]  Jeffrey Richard Crandall,et al.  Measuring the Acceleration of a Rigid Body , 1998 .

[24]  Parviz E. Nikravesh,et al.  Computer-aided analysis of mechanical systems , 1988 .

[25]  P. L. Majewski,et al.  Measurement of Head, T 1 , and Pelvic Response to -Gx Impact Acceleration , 1977 .