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
- Multi-functional Granular Propulsion: Bio-inspired Orientation Control and Local Fluidization for Crawl-to-Dig Transitions. D Li, M Tolley, N Gravish. IEEE IROS. 2025.
- Supra-resonant wingbeats in insects. E Wold, R Yang, J Lynch, E Liu, N Gravish, S Sponberg. 2025. (In Review). PREPRINT:
- Autonomous Burrowing and Retrieval of Soft Robotic Anchors in Granular Media. D Li, M Tolley, N Gravish. IEEE RoboSoft. 2025.
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
- The Weis-Fogh number describes resonant performance tradeoffs in flapping insects. E Wold, E Liu, J Lynch, N Gravish, S Sponberg. Integrative and Comparative Biology. 2024. PDF: LINK:
- Moth resonant mechanics are tuned to wingbeat frequency and energetic demands. E Wold, B Aiello, M Harris, U Bin Sikander, J Lynch, N Gravish, S Sponberg. Proceedings. Biological Sciences. 2024. PDF: LINK:
- Stability and agility trade-offs in spring-wing systems. J Lynch, E Wold, J Gau, N Gravish. Bioinspiration & Biomimetics. 2024. 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:
