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Ruotong Zhang

Publications and source records attributed to Ruotong Zhang.

2 recordsLinked to original sources
arXiv2025

Local and Global Results on Three Dimensional Rarefaction Waves in Spherical Symmetry

We construct centered rarefaction wave solutions given background solutions to the compressible Euler equations. The flow considered in this article is the homentropic flow of perfect gas governed by compressible Euler equations and the gamma-law equation of state in 3-D spherical symmetry. We prove the existence of local in time rarefactions for general background solutions, which corresponds to one side of the solution to the Riemann problem in spherical symmetry. We also prove the existence of global in time rarefactions for background solutions that are close to constant states with reasonable decay.

math.AP↗
arXiv2020

A Dexterous Tip-extending Robot with Variable-length Shape-locking

Soft, tip-extending "vine" robots offer a unique mode of inspection and manipulation in highly constrained environments. For practicality, it is desirable that the distal end of the robot can be manipulated freely, while the body remains stationary. However, in previous vine robots, either the shape of the body was fixed after growth with no ability to manipulate the distal end, or the whole body moved together with the tip. Here, we present a concept for shape-locking that enables a vine robot to move only its distal tip, while the body is locked in place. This is achieved using two inextensible, pressurized, tip-extending, chambers that "grow" along the sides of the robot body, preserving curvature in the section where they have been deployed. The length of the locked and free sections can be varied by controlling the extension and retraction of these chambers. We present models describing this shape-locking mechanism and workspace of the robot in both free and constrained environments. We experimentally validate these models, showing an increased dexterous workspace compared to previous vine robots. Our shape-locking concept allows improved performance for vine robots, advancing the field of soft robotics for inspection and manipulation in highly constrained environments.

cs.RO↗