COPY [ BIO - 11 - 1390 ] Three - Dimensional Static Modeling 1 of the Lumbar Spine

9 This paper presents three-dimensional static modeling of the 10 human lumbar spine to be used in the formation of anatomically11 correct movement patterns for a fully cable-actuated robotic 12 lumbar spine which can mimic in vivo human lumbar spine move13 ments to provide better hands-on training for medical students. 14 The mathematical model incorporates five lumbar vertebrae 15 between the first lumbar vertebra and the sacrum, with dimensions 16 of an average adult human spine. The vertebrae are connected to 17 each other by elastic elements, torsional springs and a spherical 18 joint located at the inferoposterior corner in the mid-sagittal 19 plane of the vertebral body. Elastic elements represent the liga20 ments that surround the facet joints and the torsional springs rep21 resent the collective effect of intervertebral disc which plays a 22 major role in balancing torsional load during upper body motion 23 and the remaining ligaments that support the spinal column. The 24 elastic elements and torsional springs are considered to be non25 linear. The nonlinear stiffness constants for six motion types were 26 solved using a multiobjective optimization technique. The quanti27 tative comparison between the angles of rotations predicted by 28 the proposed model and in the experimental data confirmed that 29 the model yields angles of rotation close to the experimental data. 30 The main contribution is that the new model can be used for all 31 motions while the experimental data was only obtained at discrete 32 measurement points. [DOI: 10.1115/1.4007172]