Publications

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Journal Articles

Safe Navigation in Dynamic Environments using Density Functions

Published in arXiv, 2024

This work uses density functions for safe navigation in dynamic environments. The dynamic environment consists of time-varying obstacles as well as time-varying target sets. We propose an analytical construction of time-varying density functions to solve these navigation problems. The proposed approach leads to a time-varying feedback controller obtained as a positive gradient of the density function.

Recommended citation: Sriram S. K. S. Narayanan, Joseph Moyalan, Umesh Vaidya (2024). "Safe Navigation in Dynamic Environments using Density Functions." submitted to IEEE Transactions on Automatic Control Letters.
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SE(3) Koopman-MPC: Data-driven Learning and Control of Quadrotor UAVs

Published in Modeling Estimation and Control Conference, 2023

In this paper, we propose a novel data-driven approach for learning and control of quadrotor UAVs based on the Koopman operator and extended dynamic mode decomposition (EDMD). Building observables for EDMD based on conventional methods like Euler angles (to represent orientation) is known to involve singularities. To address this issue, we employ a set of physics-informed observables based on the underlying topology of the nonlinear system.

Recommended citation: Sriram S. K. S. Narayanan, Duvan Tellez-Castro, Sarang Sutavani, Umesh Vaidya (2023). "Off-Road Navigation of Legged Robots Using Linear Transfer Operators." Modeling Estimation and Control Conference (2023) .
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Off-Road Navigation of Legged Robots Using Linear Transfer Operators

Published in Modeling Estimation and Control Conference, 2023

This paper presents the implementation of off-road navigation on legged robots using convex optimization through linear transfer operators. Given a traversability measure that captures the off-road environment, we lift the navigation problem into the density space using the Perron-Frobenius (P-F) operator. This allows the problem formulation to be represented as a convex optimization.

Recommended citation: Joseph Moyalan, Andrew Zheng, Sriram S. K. S. Narayanan, Umesh Vaidya (2023). "Off-Road Navigation of Legged Robots Using Linear Transfer Operators." Modeling Estimation and Control Conference (2023) . (best paper award)
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Safe Navigation Using Density Functions

Published in IEEE Robotics and Automation Letters, 2023

This paper presents a novel approach for safe control synthesis using the dual formulation of the navigation problem. The main contribution of this paper is in the analytical construction of density functions for almost everywhere navigation with safety and stability guarantees.

Recommended citation: Andrew Zheng*, Sriram S. K. S. Narayanan*, Umesh Vaidya (2023). "Safe Navigation Using Density Functions." IEEE Robotics and Automation Letters.
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