5 citations · 18 across the 13 of their papers we have counts for
13 papers
Symmetry Is Almost All You Need: Robust Stability with Uncertainty Induced by Symmetric SRG Regions
Ding Zhang, Di Zhao, Philipp Braun +1
This paper investigates the robust stability problem of a feedback system in the presence of uncertainties induced by graphical regions in the plane where the scaled relative graph…
Feedback Stability Under Mixed Gain and Phase Uncertainty
Jiajin Liang, Di Zhao, Li Qiu
In this study, we investigate the robust feedback stability problem for multiple-input-multiple-output linear time-invariant systems involving sectored-disk uncertainty, namely, dy…
A Cyclic Small Phase Theorem
Chao Chen, Wei Chen, Di Zhao +2
This paper introduces a brand-new phase definition called the segmental phase for multi-input multi-output linear time-invariant systems. The underpinning of the definition lies in…
Converse negative imaginary theorems
Sei Zhen Khong, Di Zhao, Alexander Lanzon
Converse negative imaginary theorems for linear time-invariant systems are derived. In particular, we provide necessary and sufficient conditions for a feedback system to be robust…
On the exponential convergence of input-output signals of nonlinear feedback systems
Lanlan Su, Di Zhao, Sei Zhen Khong
This note studies the exponential convergence of input-output signals of discrete-time nonlinear systems composed of a feedback interconnection of a linear time-invariant system an…
When Small Gain Meets Small Phase
Di Zhao, Wei Chen, Li Qiu
In this paper, we investigate the feedback stability of multiple-input multiple-output linear time-invariant systems with combined gain and phase information. To begin with, we exp…
A Frequency-Domain Approach to Nonlinear Negative Imaginary Systems Analysis
Di Zhao, Chao Chen, Sei Zhen Khong
In this study, we extend the theory of negative imaginary (NI) systems to a nonlinear framework using a frequency-domain approach. The extended notion is completely characterized v…
The Singular Angle of Nonlinear Systems
Chao Chen, Di Zhao, Sei Zhen Khong
In this paper, we introduce an angle notion called the singular angle for nonlinear systems from an input-output perspective. The proposed system singular angle, based on the angle…
Phase of Nonlinear Systems
Chao Chen, Di Zhao, Wei Chen +2
In this paper, we propose a definition of phase for a class of stable nonlinear systems called semi-sectorial systems, from an input-output perspective. The definition involves the…
Low Phase-Rank Approximation
Di Zhao, Axel Ringh, Li Qiu +1
In this paper, we propose and solve a low phase-rank approximation problem, which serves as a counterpart to the well-known low-rank approximation problem and the Schmidt-Mirsky th…
Stabilization of Cascaded Two-Port Networked Systems with Simultaneous Nonlinear Uncertainties
Di Zhao, Sei Zhen Khong, Li Qiu
We introduce a versatile framework to model and study networked control systems (NCSs). An NCS is described as a feedback interconnection of a plant and a controller communicating…
A Convex Approach to Frisch-Kalman Problem
Di Zhao, Anders Rantzer, Li Qiu
This paper proposes a convex approach to the Frisch-Kalman problem that identifies the linear relations among variables from noisy observations. The problem was proposed by Ragnar…
Stabilization of Cascaded Two-Port Networked Systems Against Nonlinear Perturbations
Di Zhao, Sei Zhen Khong, Li Qiu
A networked control system (NCS) consisting of cascaded two-port communication channels between the plant and controller is modeled and analyzed. Towards this end, the robust stabi…