Human gait modeling: dealing with holonomic constraints

Dynamical models are fundamental for the study of human gait. This work presents a complete and systematic approach to deriving control system models for both the single support phase and the double support phase of a gait cycle. We consider a nine segment model in the sagittal plane. Emphasis is placed on two important aspects of the modeling process: dealing with the holonomic constraints and dealing with the ground reaction forces. We start with a raw model which is a direct result of Newton´s law and which is subject to holonomic constraints. By characterizing the ground reaction forces, these constraints are eliminated to generate standard control system models for every possible situation in a gait cycle. These models are verified via both inverse dynamics and forward simulations on experimental data.