Dynamic model of flexion/extension and abduction/adduction of the shoulder joint complex

This work presents the modeling, control, and simulation of flexion/extension and abduction/adduction of the shoulder joint complex. The dynamic models of the shoulder movements are obtained using Euler-Lagrange formulation and are built in Simulink (MATLAB) using the nonlinear second-order differential equations derived from the dynamic analysis. An angular displacement feedback PID control, representing the human natural neuromusculoskeletal control, is implemented in the model for trajectory tracking of the shoulder movements. Simulations are carried out for the average Colombian adult and using sinusoidal waves as reference trajectories, and the angular displacement tracking is evaluated in terms of the maximum relative error (RME) and root mean square error (RMSE). Simulation results showed superior angular displacement tracking with errors below 0.82[°] in magnitude and 1.23%.