Newsletter Volume 16 - 4th Quarter 2007
A study on the human impulse characteristics of the standing shooting posture
C0NTENTS
Case Study: A study on the human impulse characteristics of the standing shooting posture.
Software: NEW! LifeMOD/LumbarSIM v2007
12 New Publications: Journal Papers, Magazine Articles and Book Chapters
This issue of the newsletter presents a study on the human impulse characteristics of the standing shooting posture. This fine work is presented by the LifeMOD team at the Chungnam National University and the Agency for Defense Development both in Korea.
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BRG becomes LifeModeler, Inc. In commemoration of many new changes planned for 2008 we have changed the company name. This reflects the introduction of several new products, many new personnel, a new web site and a new blog. All this would not be possible if it weren't for your continued support, and we sincerely wish to thank you for giving us the opportunity to bring human simulation to the next level.
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New Product Announcement! We wish to introduce an exciting new product, LifeMOD/LumbarSIM. This product automatically creates scalable lumber spine models for a variety of orthopedic, safety and comfort applications.
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We also have several new employment opportunities now available.
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In this issue we would like to announce the winner of the LifeModeler Ipod Nano contest!. Thank you to all who entered. Another contest announcement to follow.
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Finally, with the many employment inquiries from students and scientists, as well as many inquiries from our many industry clients we have decided to link up the two with the LifeMOD Employment Referral Network.
HUMAN IMPULSE CHARACTERICS OF THE STANDING SHOOTING POSTURE
Introduction
When shooting a rifle, the impact effect on the human body is determined by the posture of the human. The interaction of the human-rifle system has a significant influence on a firing accuracy. In this study, the impact analysis of a simulation model of a rifle and the human body is performed, providing data on the displacement of the rifle and transfer path of impact on the human model. The study provides insight on the optimal parameters for the most effective shooting posture.
Modeling
Human Shooter Model
For this study, LifeMOD was used to model the shooter using the internal Korean anthropometric database for a subject of 170 cm in height and weighing 60 kg. This is representative of a young man in his twenties, according to the report published at the Korean Agency for Technology and Standards. The human model was positioned in the standing firing posture displayed in figure 1, with the coordinate system displayed in figure 2. The LifeMOD Hybrid III passive joint strength library is used to model the joint characteristics during shooting. The force displacement and force velocity relationships are scaled during the analysis in order for the model to match the human performance in the experiments.
Figure 1. Comparison of human and LifeMOD model with the shooting standing posture.
Figure 2. The coordinate system of the human and rifle.
Rifle Model
In this study, the rifle used for the impulse analysis is the Daewoo K2 as used by the South Korean military. The modeling of the K2 was performed using CATIA V5. Figure 3 shows the simulation model and a photograph of the K2. The length of the weapon is 970 mm and the mass is 3.267 kg. Figure 4 displays the interfaces between the human model and the rifle. The connections between the hands, right shoulder and the rifle were modeled using 6 degree-of-freedom bushing force elements.
Figure 3. The K2 rifle model (left) and a photograph of the actual rifle.
Figure 4. Boundary conditions of the rifle and the human model supports, left hand (left), right hand (center), and shoulder (right).Simulations
The simulations were performed by applying a transmitted force history to the rifle (figure 5). The longitudinal displacement of the gun was tracked and compared between the model response and the experiment (figure 6). The joint strength characteristics in the model were tuned until the model provided acceptable displacement results as displayed in figure 6.
Figure 5. Experimental force impulse history of the rifle at the time of shooting.
Figure 6. Experimental (top) and simulation model best match impulse (bottom) history on the rifle at shooting.Discussion
During shooting, an unstable standing posture can result if the shooter's body is pushed backward. To prevent the body from being pushed backward, a rifleman will naturally compensate by applying a muscular reaction to the impulse force. This is typically done by bracing with the rifle-side leg behind the torso, and the simulation model is postured in the same way. At 0.1 seconds into the simulation, the impulse begins at the right shoulder, travels to the left shoulder, then to the hips, knees and ankles. The duration of this event is 0.002 seconds. Figure 7 displays the posture variation of human body model before and after the event.
Figure 7. Posture variation of the human body model with standing posture before (left) and after the shot (right).
Figure 8 displays the contour plot of impulse transfer path through the body in the longitudinal direction. Figure 9 displays the vector plot of the impulse transfer path through the body from 0.1 second to 0.101 second.
Figure 10 displays the contour plot of the impulse transfer path in the vertical direction. When comparing this plot to figure 8, the noticeable differences at time = 0.101 are the loading on the left (non-shooting) shoulder and the loading on the right leg to brace the the body against the firing impulse. Figure 11 displays the transfer path in the vertical direction indicating a higher load transferred to the knees for this direction than in the longitudinal direction (figure 9).
Figure 12 displays the contour plot of impulse transfer path of the body in the horizontal direction at the shooting. The plot indicates a loading on the right arm (shooting) at time = 0.1 seconds and then in the left arm at time = 0.101 seconds. This loading path indicates the model attempting to stabilize the weapon in the horizontal direction to maintain firing accuracy.
Figure 8. Contour plot of impulse transfer path of the human body part in the longitudinal direction (X) with the standing posture.
Figure 9. Vector plot of impulse transfer path of the human body part in the longitudinal direction (X) with the standing posture.
Figure 10. Contour plot of impulse transfer path of the human body part in the vertical direction (Y) with the standing posture.
Figure 11. Vector plot of impulse transfer path of the human body part in the vertical direction (Y) with the standing posture.
Figure 12. Contour plot of impulse transfer path of the human body part in the horizontal direction (Z) with the standing posture.
Figure 13. Vector plot of impulse transfer path of the human body part in the horizontal direction (Z) with the standing posture.Conclusions
The major conclusions from this study are as follows:
- Major impact forces occur at the interface between the rifle and the body.
- Maximum impact force occurs in the opposite direction of the bullet direction.
- The impact force is transferred to the lower body from the upper body and is transferred to the left from the right.
- Body natural damping frequency will have an effect on shot accuracy for an automatic (repeating) weapon.
- Body impulse trace maps and timings can have relevance in shooter training and shot accuracy.
Acknowledgements
This fine work was presented by:
- Young-Shin Lee - Dept. of Mech. Design Eng., Chungnam National University, Korea
- Young-Jin Choi- Dept. of Mech. Design Eng., Chungnam National University, Korea
- Kyu-Hyun Han - Dept. of Mech. Design Eng., Chungnam National University, Korea
- Je-Wook Chae - Agency for Defense Development, Korea
- Eui-Jung Choi - Agency for Defense Development, Korea
- In-Woo Kim - Agency for Defense Development, Korea
References
[]1. Kim, H.J., Park, Y.P., Yang, H.S., Choe, E.J., Lee, S.B. and Hong, K.J.: Investigation of Dynamic Absorbing System in the Gas-operated Gun with High Transmitted Shock Force: Journal of the Korean Society for Noise and Vibration Engineering Vol. 12, No. 5 (2002), pp. 389-396
[]2. Park, Y.P.: Design of Dynamic Absorbing System Considering Human Model Characteristics: Agency for Defense Development Report No. UD980022CD(1999)
[]3. Lee, Y.S, Choi, K.J., Cho, K.H. and Lim, H.K.: Development of Design Techniques of Plastic Ankle Foot Orthosis for the Hemiplasics I: An Approach through Stress Analysis: Transactions of the Korean Society of Mechanical Engineers Vol.26, No.1(2002), pp. 7-14
[]4. Lee, Y.S., Lee, S.K., Kim, C.J. and Park, S.J.: A Study of Measurement on Range of Arm Joint Motion of Korean Male in Twenties: Journal of the Ergonomics Society of Korea, Vol.15, No.1(1996), pp. 39-52
[]5. Zakharenkov,V.F., Arseniev,S.E., Belov,A.V., Agoshkov,O.C., Lee,Y.S., Kim,I.W. and Chae, J.W.: Modeling and Numerical Investigation of the Stochastic Biomechanical Interaction Human-Rifle System: Proceedings of the 20th International Symposium on Ballistics(2002)
[]6. Chae, J.W.: Human Anthropological and Bio-mechanical Model of Human-Rifle System: Agency for Defense Development Report No. GSDC-619-011092(2001)
[]7. Yuan, C.K.: Effects of Rifle Weight and Handling Length on Shooting Performance: Applied Ergonomics Vol. 28, No. 2(1997), pp. 121-127
SOFTWARE
LifeMOD
We would like to announce a powerful new release of LifeMOD. This release was developed as part of our long-term modeling strategy and with close cooperation from commercial clients and our university consortium. The user interface has been completely restructured and has been reorganized with libraries for motion capture data sets, models, postures, environments, contact conditions, etc. We have also expanded our muscle modeling capability to include Hill type muscles in addition to our LifeMOD trainable muscle elements. There is a muscle wrapping tool which can model very accurate lines of action as muscles wrap and slide around structures. We have included ergonomic features such as vision cones and body center-of-mass reporting. We have expanded the self-training tutorials to include a tennis player, grasping hand, and detailed whiplash model (featured in a previous newsletter, Volume 14). This functionality is in addition to many convenience features that you will see in the program.
LifeMOD/KneeSIM
We would like to introduce a new version of LifeMOD/KneeSIM, a complete virtual product development solution for Total Knee Replacement Systems. The product, developed in collaboration with the world's leading orthopedic companies, can be used for in vivo simulation to ensure proper tibial rotation, validate femoral rollback, minimize patella shear, maximize quadriceps efficiency and increase durability and design robustness. LifeMOD/KneeSIM has proven itself in the design of PCL/ACL sacrificing/retaining and fixed/mobile bearing component systems. With simulation times of less than five minutes, hundreds of design iterations may be characterized in a day. With this powerful tool, engineers gain insight into cause and effect relationships between design changes and response in the body. See case study. See press release.
LifeMOD/NeckSIM
We would also like to introduce a new product, LifeMOD/NeckSIM, a complete detailed cervical spine modeling tool. LifeMOD/NeckSIM is a plug-in to the main LifeMOD program offering the incorporation of very detailed cervical spine models in a full body LifeMOD model. LifeMOD/NeckSIM automates the vertebrae discretization, disk force generation and soft tissue generation. The muscles may be either Hill-type or trainable LifeMOD elements. Complete with the new tissue wrapping feature, accurate lines of action may also be represented in the spine model. This tool has great utility with applications in injury, safety, orthopedics, surgical simulation, etc. See case study.
LifeMOD/LumbarSIM
We would like to announce the availability of an exciting new product, LifeMOD/LumbarSIM. This product, similar to LifeMOD/NeckSIM, automatically creates a scalable lumbar spine. This model is easily created by a few mouse clicks and provides very high fidelity. This new feature has direct applications in our traditional customer base such as orthopedics, safety, comfort, ergonomics, etc.
Learn more by visiting our web page or by contacting us at newsletter@lifemodeler.com.
SERVICES
The Biomechanics Research Group, Inc. is a service-based organization with many major commercial successes using LifeMOD human simulation in the design process. We are expert in the development of the appropriate models, simulation cases and human response signature development to accelerate innovation of your product and greatly reduce the time to market. Contact us to see how we have done this in many industries.OTHER NEWS
LifeMOD/KneeSIM
To replicate normal knee function, Smith & Nephew conducted in-depth analyses of natural knee kinematics and the inherent limitations in knee replacement systems. LifeMOD/KneeSIM played a key role in this investigation. "We chose to partner with BRG because of their experience, technology, and expertise in the area of applying virtual product development engineering to human activity," states Brian McKinnon, one of the lead engineers on the Journey Knee Program. This effort led to the innovative JOURNEY anatomical knee system designed to move and feel like a normal knee, and addresses problems still found in conventional systems such as instability and limited flexion. The new Journey Knee System was voted the "Best in Show" at the 2006 AAOS meeting in Chicago last year. See press release.
ORL
This month we are excited to announce the expansion of our partnership with the Orthopaedic Research Laboratories, in Cleveland Ohio, under the direction of A. Seth Greenwald, D.Phil. (Oxon). In addition to using LifeMOD/KneeSIM as a basis for comparative studies between commercially available total knee replacement systems, they have chosen LifeMOD/NeckSIM as a basis of comparative studies for spinal devices. These capabilities will complement their existing efforts to provide functional performance data to a significant number of national and international manufacturers, the Food and Drug Administration (FDA) and the orthopaedic surgeon community. All these efforts are directed toward an optimization of surgical techniques, orthopaedic devices and surgeon education to improve patient outcome.
Ipod Nano Contest Winner
Brian Schultz, Ph.D., a program specialist at the James A. Haley Veterans' Hospital in Tampa, Florida is the winner of the LifeMOD movie contest. Brian submitted the movie seen below of a person falling out of bed while actively bracing for the impact. We would like to thank the many students and researchers who submitted entries, and we look forward to the next contest.
LifeMOD User Forum
In an effort to foster communication with the worldwide LifeMOD community at large, we are introducing theLifeMOD User Forum. In addition to LifeMOD users we have many experts in the general multibody dynamics community enlisted to help answer general ADAMS-related questions. Please join today and take part in this very active knowledge base.
Partners
To respond to the ever-growing LifeMOD community we have developed partnerships with several more full service resellers across the world including:
- China - Zhongtian-Noah Sports Science Co. Ltd.
- France - INCAT France
- Germany - VI-Grade, LLC
- Greece - O Vision 2000 S.A.
- India - CSM Software Private Ltd.
- Italy - Lista Studio, SRL
- Japan - Inter-Reha Co., Ltd.
- Japan - Nihon VI-Grade
- Korea - AhTTi
- Netherlands - SayField International
- Romania - Magic Engineering, SRL
- South Africa - MSC-Africa Simulating Reality (Pty), Ltd.
- Spain - Analisis y Simulacion S.L.
- Taiwan - Taiwan Auto-Design Co.
- Thailand - Sigma Solutions Co., Ltd.
- Turkey - Bias Muhendislik/Engineering
- UAE - Nezmin Trading
- UK - Marlbrook, Ltd.
- USA - Diverse Solutions, Inc.
- USA - ESA Corp.
Referral Network
Throughout the years, we have received many employment inquiries from student graduates and professionals seeking employment to utilize their skills with LifeMOD. Also, we have been repeatedly asked for references by our top industry clients for LifeMOD-trained talent. We have decided to combine both these needs in the LifeMOD Employment Referral Network. If you are a LifeMOD trained investigator or an industry professional in need of a LifeMOD trained investigator please contact us.
If you would like further information on our software and services, please give us a call.
Copyright© 2007 LifeModeler, Inc.