2.5k citations · 3.4k across the 22 of their papers we have counts for
22 papers
Backward Reachability Analysis of Neural Feedback Systems Using Hybrid Zonotopes
Yuhao Zhang, Hang Zhang, Xiangru Xu
The proliferation of neural networks in safety-critical applications necessitates the development of effective methods to ensure their safety. This letter presents a novel approach…
Adaptive Safety-Critical Control for a Class of Nonlinear Systems with Parametric Uncertainties: A Control Barrier Function Approach
Yujie Wang, Xiangru Xu
This paper presents a novel approach for the safe control design of systems with parametric uncertainties in both drift terms and control-input matrices. The method combines contro…
Reachability Analysis and Safety Verification of Neural Feedback Systems via Hybrid Zonotopes
Yuhao Zhang, Xiangru Xu
Hybrid zonotopes generalize constrained zonotopes by introducing additional binary variables and possess some unique properties that make them convenient to represent nonconvex set…
Optimal Control for Kinematic Bicycle Model with Continuous-time Safety Guarantees: A Sequential Second-order Cone Programming Approach
Victor Freire, Xiangru Xu
The optimal control problem for the kinematic bicycle model is considered where the trajectories are required to satisfy the safety constraints in the continuous-time sense. Based…
Small-Gain Theorem for Safety Verification under High-Relative-Degree Constraints
Ziliang Lyu, Xiangru Xu, Yiguang Hong
This paper develops a small-gain technique for the safety analysis and verification of interconnected systems with high-relative-degree safety constraints. In this technique, input…
Safety Verification of Neural Feedback Systems Based on Constrained Zonotopes
Yuhao Zhang, Xiangru Xu
Artificial neural networks have recently been utilized in many feedback control systems and introduced new challenges regarding the safety of such systems. This paper considers the…
Disturbance Observer-based Robust Control Barrier Functions
Yujie Wang, Xiangru Xu
This work presents a safe control design approach that integrates the disturbance observer (DOB) and the control barrier function (CBF) for systems with external disturbances. Diff…
Flatness-based Quadcopter Trajectory Planning and Tracking with Continuous-time Safety Guarantees
Victor Freire, Xiangru Xu
This work presents a convex optimization framework for the planning and tracking of quadcopter trajectories with continuous-time safety guarantees. Using B-spline basis functions a…
Observer-based Control Barrier Functions for Safety Critical Systems
Yujie Wang, Xiangru Xu
This paper considers the safety-critical control design problem with output measurements. An observer-based safety control framework that integrates the estimation error quantified…
Control Barrier Function Meets Interval Analysis: Safety-Critical Control with Measurement and Actuation Uncertainties
Yuhao Zhang, Sequoyah Walters, Xiangru Xu
This paper presents a framework for designing provably safe feedback controllers for sampled-data control affine systems with measurement and actuation uncertainties. Based on the…
Small-Gain Theorem for Safety Verification of Interconnected Systems
Ziliang Lyu, Xiangru Xu, Yiguang Hong
A small-gain theorem in the formulation of barrier function is developed in this work for safety verification of interconnected systems. This result is helpful to verify input-to-s…
Finding Matrix Sequences with a High Asymptotic Growth Rate for Linear Constrained Switching Systems
Yuhao Zhang, Xiangru Xu
Linear constrained switching systems are linear switched systems whose switching sequences are constrained by a deterministic finite automaton. This work investigates how to genera…
Periodic Event-triggered Control for Incrementally Quadratic Nonlinear Systems
Xiangru Xu, Adam M. Tahir, Behcet Acikmese
Periodic event-triggered control (PETC) evaluates the triggering rule periodically and is well-suited for implementation on digital platforms. This paper investigates PETC design f…
Passivity-Based Analysis of Sampled and Quantized Control Implementations
Xiangru Xu, Necmiye Ozay, Vijay Gupta
This paper studies the performance of a continuous controller when implemented on digital devices via sampling and quantization, by leveraging passivity analysis. Degradation of pa…
Approximation of The Constrained Joint Spectral Radius via Algebraic Lifting
Xiangru Xu, Behcet Acikmese
This paper studies the constrained switching (linear) system which is a discrete-time switched linear system whose switching sequences are constrained by a deterministic finite aut…
Successive Convexification: A Superlinearly Convergent Algorithm for Non-convex Optimal Control Problems
Yuanqi Mao, Michael Szmuk, Xiangru Xu +1
This paper presents the SCvx algorithm, a successive convexification algorithm designed to solve non-convex constrained optimal control problems with global convergence and superli…
Observer-Based Controllers for Incrementally Quadratic Nonlinear Systems with Disturbances
Xiangru Xu, Behcet Acikmese, Martin J. Corless
Robust global stabilization of nonlinear systems by observer-based feedback controllers is a challenging task. This article investigates the problem of designing observer-based sta…
Robustness of Control Barrier Functions for Safety Critical Control
Xiangru Xu, Paulo Tabuada, Jessy W. Grizzle +1
Barrier functions (also called certificates) have been an important tool for the verification of hybrid systems, and have also played important roles in optimization and multi-obje…
Correctness Guarantees for the Composition of Lane Keeping and Adaptive Cruise Control
Xiangru Xu, Jessy W. Grizzle, Paulo Tabuada +1
This paper develops a control approach with correctness guarantees for the simultaneous operation of lane keeping and adaptive cruise control. The safety specifications for these d…
Control Barrier Function Based Quadratic Programs for Safety Critical Systems
Aaron D. Ames, Xiangru Xu, Jessy W. Grizzle +1
Safety critical systems involve the tight coupling between potentially conflicting control objectives and safety constraints. As a means of creating a formal framework for controll…
Passivity Degradation In Discrete Control Implementations: An Approximate Bisimulation Approach
Xiangru Xu, Necmiye Ozay, Vijay Gupta
In this paper, we present some preliminary results for compositional analysis of heterogeneous systems containing both discrete state models and continuous systems using consistent…
Leader-following Consensus of Multi-agent Systems over Finite Fields
Xiangru Xu, Yiguang Hong
The leader-following consensus problem of multi-agent systems over finite fields is considered in this paper. Dynamics of each agent is governed by a linear equatio…