Measuring dynamic characteristics of the human arm in three dimensional space

This work describes a method to measure the three-dimensional dynamic characteristics of the human arm. Endpoint dynamics, which characterizes the relationship between hand displacements and resulting forces, was estimated during the application of three-dimensional stochastic displacement perturbations applied to the endpoint of the arm. The dynamic input-output relations between the displacements and the forces were determined using a frequency domain nonparametric system identification technique. Endpoint inertia, viscosity and stiffness parameters were fit to the identified system. A graphical technique was introduced to help visualize these complex dynamic parameters. The results illustrate the importance of studying the endpoint dynamics in three dimensions.