Pawel Bujalski
MPP, Visiting Graduate Student in the MVL
“Modeling and simulating the neuromuscular mechanisms regulating ankle joint stiffness during human locomotion”
The broad aim of this research project is to explore new designs of robotic devices for physical rehabilitation and augmentation of humans. Under the hypotheses that impedance shaping, achieved through a control network of muscle actuation and proprioceptive sensing, regulates human motion, the proposed research targets the following key points:
- To devise and implement human performance experiments in order to uncover and model the biological impedance variation methods adopted during different tasks in locomotion and manipulation.
- To devise bio-inspired sensing estimation and control algorithms for impedance shaping.
- To explore the embodiment of the developed algorithms in compliant exoskeletons, as well as in functional electrical stimulation.
For this purpose, an electrophysiologically and dynamically consistent musculoskeletal model to predict stiffness in the human ankle as derived from the joints constituent biological tissues (i.e., the spanning musculotendon units) is employed.
The EMG-driven musculoskeletal model estimates musculotendon and resulting joint stiffness that is consistent with experimental EMG data as well as with the experimental joint moments. This provides a framework that allows observing 1) the individual muscle contribution to joint stiffness, and 2) the underlying co-contraction strategies. It provides a theoretical description of how stiffness modulates as a function of muscle activation, fiber contraction, and interacting tendon dynamics. This work offers a theoretical and computational basis for describing and investigating the neuromuscular mechanisms underlying human locomotion.