Tongjia Zheng's Homepage

Swarm Robotics

Motivation

Environmental monitoring and control
Need to control the spatial and temporal evolution of the swarm distribution

Novelty

A density-based swarm control framework
Study planning, decentralized estimation, distributed control, and stability in the space of densities
Maintain a connection between microscopic and macroscopic behaviors

Mean-Field Modeling

Microscopic: individual robots are modeled by SDEs/ODEs
Macroscopic: the swarm density is modeled by a PDE
Micro-macro equivalence: directly convert PDE-based design into individual robot controllers

Decentralized Density Estimation

Communication-based local swarm density estimation as PDE state estimation problems
Convergence of density estimates is guaranteed

[3] Tongjia Zheng, Qing Han, and Hai Lin. "Distributed mean-field density estimation for large-scale systems." IEEE Transactions on Automatic Control 67.10 (2021): 5218-5229.

[4] Tongjia Zheng, Qing Han, and Hai Lin. "PDE-based dynamic density estimation for large-scale agent systems." IEEE Control Systems Letters 5.2 (2020): 541-546.

Distributed Density Feedback Control

Diffusion-inspired design of navigation fields as feedback functions of the real-time swarm density
Distributed backstepping design from the macroscopic PDE controller to individual robot controllers
Convergence of the density tracking is guaranteed

[1] Tongjia Zheng, Qing Han, and Hai Lin. "Transporting robotic swarms via mean-field feedback control." IEEE Transactions on Automatic Control 67.8 (2021): 4170-4177.

[2] Tongjia Zheng, Qing Han, and Hai Lin. "Backstepping Mean-Field Density Control for Large-Scale Heterogeneous Nonlinear Stochastic Systems." 2022 American Control Conference (ACC). IEEE, 2022.

Soft Robotics

Motivation

Surgical application, industrial inspection
Need precise and stable estimation and control

Novelty

An energy-based framework
One design for all discretization
Efficient computation and guaranteed stability

Continuum Mechanics Modeling

Viewed as a continuum limit of rigid-link robots
Modeled by partial differential equations in SE(3)

State Estimation: Boundary Observer

Dissipation-inspired estimation of all continuum states from only tip sensing
Convergence of state estimates is guaranteed

[6] Tongjia Zheng, Qing Han, and Hai Lin. "Full State Estimation of Soft Robots From Tip Velocities: A Cosserat-Theoretic Boundary Observer." IEEE Transactions on Automatic Control (to appear).

[9] Tongjia Zheng, Ciera McFarland, Margaret Coad, and Hai Lin. "Estimating Infinite-Dimensional Continuum Robot States From the Tip." 2024 IEEE 7th International Conference on Soft Robotics (RoboSoft). IEEE, 2024.

Energy-Based Control

Dissipation-inspired feedback design of discrete actuation from desired continuum configurations

[5] Tongjia Zheng, Qing Han, and Hai Lin. "Task Space Tracking of Soft Manipulators: Inner-Outer Loop Control Based on Cosserat-Rod Models." in American Control Conference (ACC), 2023

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