Mechanical Intelligence of Locomotion and Intrusion in Slender Organisms in Terradynamically Rich Terrain

Most organisms navigate complex, heterogeneous, and unpredictable environments to survive. While the genes and cellular networks that regulate navigation, growth, and other exploratory behaviors differ, diverse living systems face common physical challenges. This suggests the possibility that at the organismal level, common control strategies (and hence general principles of movement) exist across living systems despite dramatic differences in the underlying biological mechanisms. In contrast to insights gained into movement in hydro and aerodynamics environments, principles by which organisms interact with complex, heterogeneous “terradynamically rich” environments are less understood. In such environments, organisms respond to ever-changing and unpredictable local interactions with limited sensory information; the strength of the interactions implies that the organism and its environment are highly coupled and cannot be regarded as independent systems. The centrality of the physical dynamics and incompleteness of environmental information suggests that terradynamically rich environmental locomotion requires both closed-loop, active sensory feedback (commonly associated with neural control in animals or decentralized chemical cues in plants) and open-loop, passively controlled, and purely physical processes. These latter processes, in which body-environment interactions are tuned to produce adaptive exploratory behaviors without the aid of active feedback control, constitute a mechanical intelligence. In this award the team of investigators seek to discover where, when, and how active closed-loop control and passive, mechanically intelligent control mechanisms interact to create goal-oriented organism movement in terradynamically rich environments. To do so they will use model systems that face similar challenges within their physical environments: 1) O. sativa (rice) and A. thaliana roots which must navigate complex soil environments; 2) C. elegans nematodes which undulate in soil and dense, rotting vegetative tissue; 3) limbless robots in dense, heterogeneous terrains, such as those encountered in agricultural areas and search and rescue operations. The investigators will study the kinematics, forces and genetics responsible for effective function. More broadly, their findings can give insight into the role of mechanics and control in evolution and organismal behavior, and at the same time, allow us to develop robots which can traverse natural environments with performance comparable to living systems. The studied biological and robotic systems are also natural subjects of popular interest and the scientific insights gained will be leveraged for educational and outreach purposes. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.