Gravish·lab
Gravish
·
lab


The science & engineering of
dynamic & dexterous movement
Mechanical & Aerospace Engineering, UC San Diego
Flexible and compliant robotics

Flexibility and compliance can be beneficial for mobile robots that have to navigate unstrucured environments. Limbs and bodies that can bend in response to unexpected perturbations enable effective movement capabilities. Flexible appendages also offer the opportunity for body-reconfiguration to suit the task at hand. We are developing new methods to fabricate flexible, compliant, and soft robots with a focus on locomotion and reconfiguration capabilities.

Recent papers
  • A reconfigurable soft linkage robot via internal virtual joints. M Jiang, J Wang, N Gravish. Soft Robotics. 2023.    (In Review).   
  • Multi-modal Locomotion in a Soft Robot through Hierarchical Actuation. Q Yu, N Gravish. Soft Robotics. 2023.    PDF:         LINK:        
  • Scalable fluidic matrix circuits for controlling large arrays of individually addressable actuators. S Jadhav, P Glick, M Ishida, C Chan, I Abidnazari, J Shulze, N Gravish, M Tolley. Advanced Intelligent Systems. 2023.    PDF:         LINK:        
Collective Behavior

Biologists and roboticists have long been interested in how collective groups of agents can make decisions and move together. In this work we are interested in understanding how robotic collectives can coordinate their movement through minimal, and often no, communication. Recent work has focused on how mechanical interactions in high-density collectives can be used to transfer information through the group. The primary example has been how undulatory robots can collectively synchronize their gaits for coordinated locomotion.

Recent papers
  • Lateral contact yields longitudinal cohesion in active undulatory systems. W Zhou, J Dezha-Peralta, Z Hao, N Gravish. Physical Review E. 2022.    PDF:         LINK:         PREPRINT:        
  • Proprioceptive feedback design for gait synchronization in collective undulatory robots. Z Hao, W Zhou, N Gravish. Advanced Robotics. 2022.    PDF:         LINK:        
  • Collective synchronization of undulatory movement through contact. W Zhou, Hao, Z, N Gravish. Physical Review X. 2021.    PDF:         LINK:         PREPRINT:        
Legged locomotion

Running dynamics for small scale insects and robots are poorly understood. We explore legged movement at the small-scale by performing biomechanics experiments on high-speed running ants. We use micro-robotic models to test hypothesis of dynamic running in small scale systems.

Recent papers
  • The bumpy road ahead: The role of terrain roughness on animal walking, and where to go from here. G Clifton, A Stark, C Li, N Gravish. Journal of Experimental Biology. 2023.    PDF:         LINK:        
  • Directionally Compliant Legs Enable Crevasse Traversal in Small Ground-based Robots. E Lathrop, M Tolley, N Gravish. Advanced Intelligent Systems. 2023.    PDF:         LINK:        
  • Walking is like slithering: a unifying, data-driven view of locomotion. D Zhao, G Clifton, B Bittner, N Gravish, S Revzen. Proceedings of the National Academy of Sciences. 2022.    PDF:         LINK:        
Flapping wing flight

Power efficiency of milli-scale robots can be improved through mechanical designs incorporating elastic structures for energy storage and recovery. Locomotion movements are often periodic (flapping wings, running gaits) and so actuation and power transmission through resonant systems could be beneficial. However, resonance and agility require conflicting modes of actuation: resonance favors actuation at a single frequency and agility favors actuation across a wide range of frequencies. W e seek to resolve this conflict in locomotion efficiency and agility through novel mechanical design of compliant microrobots.

Recent papers
  • Bridging two insect flight modes in evolution, physiology and robophysics. J Gau, J Lynch, B Aiello, E Wold, N Gravish, S Sponberg. Nature. 2023.    PDF:         LINK:        
  • Structural damping renders the insect exoskeleton mechanically insensitive to non-sinusoidal deformations. E Wold, J Lynch, N Gravish, S Sponberg. J. Roy. Soc. Interface. 2023.    PDF:         LINK:         PREPRINT:        
  • Going against the flow: Bumblebees prefer to fly in headwinds, and display more variable body angles and ground speeds in tailwinds. S Combes, N Gravish, S Gagliardi. Journal of Experimental Biology. 2023.    PDF:         LINK:        
Locomotion in granular media

Granular materials such as sand comprise a large portion of the Earth's surface. Yet robot movement within a granular substrate is still an extremely challenging task. In this project we combine physics based study of granular flow mechanics, with robot design and locomotion studies, towards development of small mobile robots capable of movement through sand.

Recent papers
  • Toward Robotic Sensing and Swimming in Granular Environments using Underactuated Appendages. S Chopra, D Vasile, S Jadhav, M Tolley, N Gravish. Advanced Intelligent Systems. 2023.    PDF:         LINK:        
  • Continuous Skin Eversion Enables an Untethered Soft Robot to Burrow in Granular Media. K Eken, N Gravish, M Tolley. IEEE RoboSoft. 2023.    PDF:         LINK:        
  • Anisotropic Forces for a Worm-Inspired Digging Robot. D Drotman, S Chopra, N Gravish, M Tolley. IEEE RoboSoft. 2022.    PDF:         LINK: