11/1/2006

This folder contains a customized application of the UWPipeline software. 

Simulation of walking with a 3D, 23DOF model of the ful body, driven by 92 Hill-Type muscle tendon units.  The pelvis is the base segment w/ 6 DOF.  Each limb has 7 DOF relative to the pelvis with a 3 DOF hip, 1 DOF knee, 2 DOF ankle-subtalar joint and 1 DOF toe.  A head-arms-trunk is linked to the pelvis by a 3 DOF low-back joint.  See the references below for further details. 

Processing Sequency:
1) Scaling of generic model based on marker positions recorded in an upright ocnfiguration
2) Inverse kinematics computation of joint angles that track the measured marker kinematics during gait
3) Residual Elimination Algorithm is used to resolve inconsistencies between measured ground reactions and kinematics
4) Computed Muscle Control is used to compute muscle excitations necessary to track the motion.  

Also included are:
5) A forward simulation tool, which reproduces the motion based on the calculated excitations. 
6) An inverse dynamics program, which computes the torques using the whole body model. 

Notes:
1) Experimentally recorded ground reaction forces are applied directly in the forward simulations
2) There are no spring-damper elements in the forward simulations.  They were previously used in Thelen and Anderson 2006, but are not generally necessary
3) The residual elimination algorithm in Thelen and Anderson (2006) has been extended to allow the manipulation of more than 6 kinematic trajectories to balance the overall equations of motion.  This is done using a least squares formulation.  The choice of which trajectories to manipulate is made by the user in reaparams.txt.



   References:                                                                 
                                                                               
    Delp, S.L., Loan, J.P., Hoy, M.G., Zajac, F.E., Topp E.L., Rosen, J.M.: An 
    interactive graphics-based model of the lower extremity to study           
    orthopaedic surgical procedures,  IEEE Transactions on Biomedical          
    Engineering, vol. 37, pp. 757-767, 1990.                                   
                                                                               
    Anderson FC and Pandy MG. A dynamic optimization solution for vertical     
    jumping in three dimensions. Computer Methods in Biomechanics and          
    Biomedical Engineering 2:201-231, 1999.                                    
                                                                               
    Anderson FC and Pandy MG. Dynamic optimization of human walking.           
    Journal of Biomechanical Engineering 123:381-390, 2001.                    

    Thelen DG, Anderson FC.  Using computed muscle control to generate forward dynamic 
    simulations of human walking from experimental data, Journal of Biomechanics, 
    39:1107-1115, 2006