The University of Michigan’s 3D Static Strength Prediction Program TM (3D SSPP) is based on over 30 years of research at the Center for Ergonomics regarding the biomechanical and static strength capabilities of the employee in relation to the physical demands of the work environment.
A technical discussion of the static strength model used in the program is provided in Chapter 6 of Occupational Biomechanics, 4th Edition by Chaffin and Andersson, 2006 (published by J. Wiley & Sons, Inc., 605 Third Ave., New York, NY 10158). Worker strengths used for the prediction model have been compiled from a collection of strength studies described and referenced in the same textbook, in addition to other studies (found in the scientific journals) which offer strength data updates on experimental joint strength capabilities of industrial and civilian populations. Results from this model demonstrate a strong correlation with average population static strengths (r = 0.8).
To aid in posture entry, the inverse kinematics algorithm was developed from research on the preferred postures of individuals manipulating loads with known hand positions. This behavioral-based algorithm is intended to provide a first approximation of the posture based on the specified hand positions and the specified hand loads. However, the inverse kinematics algorithm may not yield a posture representative of the actual posture being modeled since the actual posture can be affected by individual factors such as differences in body type, postural preference and training as well as environmental factors such as the nature of the object being handled, workplace obstructions, traction and the feet-floor interface, and worker apparel. To minimize these effects, only experienced workers should be observed performing the tasks in question. Should additional posture modifications be necessary, the program contains easy-to-use methods for altering the initial predicted posture to more closely represent the posture observed in the workplace.