Quantitative Biosciences Thesis Proposal

Jianfeng Lin 

School of Physics

Undulatory Locomotion Neuromechanics in Highly Damped Environments

Thursday, June 12, 2025, at 11:00 am

In Person Location: Howey N201/202

Meeting Link: https://gatech.zoom.us/j/93130170508

Open to the Community

Advisor:

Dr. Daniel I. Goldman (School of Physics)

Committee Members:

Dr. Simon Sponberg (School of Physics, School of Biological Sciences)

Dr. Hang Lu (School of Chemical and Biomolecular Engineering)

Dr. Henry Astley (Biomimicry Research & Innovation Center, University of Akron)

Abstract:

Animal locomotion emerges from complex interactions between neural and musculoskeletal systems within diverse environments. Undulation with traveling waves is commonly observed in elongated-body organisms from millimeter-scale nematodes to centimeter-scale snakes and lizards, exhibiting kinematic similarity in highly damped environments (low Reynolds number fluids and frictional granular materials). However, how neuromechanical systems enable adaptive and robust undulatory locomotion through interactions between viscoelastic bodies and contact-rich environments remains unclear. My research will focus on the general principle of how body viscoelasticity and proprioception benefit locomotion in homogeneous and heterogeneous environments.

First, I study the unique role of multiarticular muscles, observed in snakes and lizards. Previous studies suggest that undulatory animals in highly damped environments, such as the sandfish lizard (Scincus scincus) and shovel-nosed snake (Chionactis occipitalis), require higher joint torque and energy consumption in their mid-bodies. I hypothesize that multiarticular muscles enable a rebalancing of torque and energy along the body. I hypothesize multiarticular muscles rebalance torque and energy distribution. I explore these muscles anatomically through dissections and microCT scans of sandfish, and test the hypothesis using a robophysical model with coupled springs.

Second, I investigate how proprioceptive feedback enables gait adaptation in homogeneous environments by studying the millimeter-scale nematodes C. elegans, which adapt their gait in viscous fluids. I model the proprioception by introducing sensing of position and velocity, along with their spatial integration. I hypothesize proprioception senses environmental drag and anisotropy, potentially extending to other frictional environments, tested using a proprioception-controlled robophysical model.

Third, I explore proprioceptive feedback's role in gait adaptation within heterogeneous environments. I hypothesize simple proprioceptive feedback observed in C. elegans enables adaptation to ordered lattices but requires higher-level control as environmental disorder increases. A proprioception-driven robophysical model navigating heterogeneous lattices tests these hypotheses.