Xiaofeng Zong

China University of Geosciences · School of Automation

Soft actuators typically exhibit low stiffness and low load-bearing properties due to the intrinsic limitations of soft materials. Stiffness modulation is an effective means to improve the performance of soft actuators. However, most stiffness-tunable mechanisms are nonstretchable, and have difficulty in independently adjusting the tensile stiffnes...

This paper is concerned with group consensus of multi-agent systems (MASs) that consist of two groups in additive noise environments. First, a control protocol is proposed based on the state information of each agent’s neighbors corrupted by additive noises. Second, some sufficient conditions and necessary conditions are obtained for the following...

This paper studies the stochastic leader-following consensus problem of discrete-time nonlinear multi-agent systems (MASs) with multiplicative noises. The measurement information obtained from agents’ neighbors is inevitably affected by communication uncertainties, where the multiplicative noise is one of the important communication uncertainties....

The use of surface electromyography (sEMG) signals gains importance in rehabilitation and sports science because it provides a noninvasive and convenient way to analyze the activities of muscles. Since sEMG signals are weak, nonstationary electrical signals mixed with baseline noise, motion artifacts, power line interference, and many other types o...

It is a key challenge for soft grasping devices to stably grasp unstructured objects with multi-size and multi-shape. The conventional single-function grippers have some limitations in grasping the above kinds of objects. This work proposes a modular four-modal soft grasping device (MFSGD), which consists of soft fingers, suction cups, soft wrapper...

Purpose The aim of the paper is to propose a global, automated and continuous curvature calibration strategy for bending sensors, which is used for the angle feedback control of soft fingers. Design/methodology/approach In this work, the proposed curvature calibration strategy for bending sensors is based on the constant curvature bending properti...

In this paper, we propose a fully Soft Bionic Grasping Device (SBGD), which has advantages in automatically adjusting the grasping range, variable stiffness, and controllable bending shape. This device consists of soft gripper structures and a soft bionic bracket structure. We adopt the local thin-walled design in the soft gripper structures. This...

The online small-signal stability assessment of electrical power grids is typically a challenging problem due to uncertainties and parameter variations of power system dynamics as well as the incurred high computational complexity. This paper proposes a novel theoretical framework for dynamic small-signal stability assessment of power grids by esti...

A new kind of group coordination control problem-group hybrid coordination control is investigated in this paper. The group hybrid coordination control means that in a whole multi-agent system (MAS) that consists of two subgroups with communications between them, agents in the two subgroups achieve consensus and containment, respectively. For MASs...

Soft elongation actuators are widely applied in soft robotic grippers, providing a promising solution to adjust the grasping range. However, there are some limitations in keeping their tensile shaping stability under high payloads. This work presents a universal variable stiffness mechanism called Cross-Fibre to reduce the deformation and improve t...

This paper studies the consensus problem of heterogeneous multi-agent systems (MASs) composed of first-order and second-order agents. To describe the communication environment realistically, the effect of the multiplicative noise on the communication network is considered. Firstly, the consensus problem is transformed into the stability problem of...

This paper investigates the containment problem of continuous-time multi-agent systems with multiplicative noises, where the first-order and second-order multi-agent systems are studied respectively. Based on stochastic analysis tools, algebraic graph theory, and Lyapunov function method, the containment protocols based the relative states measurem...

This article investigates time‐varying formation control problems of linear multiagent systems with time delays and multiplicative noises under the undirected interactive topology. First, the time‐varying formation control problem under time delays and multiplicative noises is transformed into the asymptotic stability problem of a closed‐loop stoch...

This study investigates periodic event‐triggered (PET) output‐feedback control method for nonlinear systems with quantized states and multisource disturbances. Based on a PET extended state observer, a novel PET composite control method is proposed. It not only can deal with the deterministic and stochastic disturbances but also can handle the quan...

This chapter is devoted to studying the consensus control of continuous-time multi-agents systems with general noises and delays. By using the stochastic analysis, matrix theory, and algebraic graph theory, conditions on the stochastic approximation-type protocol are obtained for mean square and almost sure weak and strong consensus under the gener...

This article establishes a “robustness” type result, namely, delay tolerance for stable stochastic systems under suitable conditions. We study the delay tolerance for stable stochastic systems and delayed feedback controls of such systems, where the delay can be state-dependent or induced by the sampling-data. First, we consider systems with global...

This study discusses delay‐dependent stability of a class of stochastic delay systems driven by G‐Brownian motion in the sublinear expectation space. With the help of the degenerate Lyapunov functional, the mean square exponential stability and quasi‐sure exponential stability criteria for stochastic delay systems driven by G‐Brownian motion are es...

In this paper, the finite-time stabilization problem for memristor-based inertial neural networks (MINNs) with discontinuous activations (DAs) and distributed delays is investigated. To deal with the discontinuous property of the MINNs, the nonsmooth analysis theory is invoked. Furthermore, to simplify the MINNs with second-order state derivative,...

By using the Razumikhin-type technique, for stochastic discrete-time delay systems, this paper establishes the discrete Razumikhin-type theorems on the pth moment stability, the global pth moment stability and the pth moment exponential stability, respectively. The almost sure exponential stability is also investigated by using the pth moment expon...

This paper studies the consensus control of second‐order multiagent systems with intrinsic dynamics based on delayed and noisy measurements, where the delays in the position and velocity measurements are allowed to be different. The nonlinear and linear intrinsic dynamics are considered, respectively. For the case with nonlinear dynamics, mean squa...

Motivated by the seminal work of Dupire (2009) on functional Itô formulas, this work investigates asymptotic properties of systems represented by stochastic functional differential equations (SFDEs). Stability of general delay-dependent SFDEs is investigated using degenerate Lyapunov functionals, which are only positive semi-definite rather than po...

This work is concerned with the consensus problem of multi-agent systems with additive and multiplicative measurement noises. By developing general stochastic stability lemmas for nonautonomous stochastic differential equations, stochastic weak and strong consensus conditions are investigated under fixed and time-varying topologies, respectively. F...

This work develops stochastic consentability of linear multi-agent systems with time delays and multiplicative noises. First, the stochastic stability for stochastic differential delay equations (SDDEs) driven by multiplicative noises is examined, and the existence of the positive definite solution for a class of generalized algebraic Riccati equat...

In this paper, we address the consensus control of stochastic multi-agent systems with intrinsic dynamics based on measurements with time-delay and multiplicative noises under undirected graphs. By developing degenerate Lyapunov functional and stochastic stability theorem, we establish mean square and almost sure consensus conditions explicitly rel...

Based on the martingale theory and large deviation techniques, we investigate the p th moment exponential stability criterion of the exact and numerical solutions to hybrid stochastic differential equations (SDEs) under the local Lipschitz condition. This new stability criterion shows that Markovian switching can serve as a stochastic stabilizing f...

This work is concerned with stochastic consensus conditions of multi-agent systems with both time-delays and measurement noises. For the case of additive noises, we develop some necessary conditions and sufficient conditions for the stochastic weak consensus by estimating the differential resolvent function for functional equations. By the martinga...

In this work, we propose two classes of two-step Milstein-type schemes : the double-implicit Milstein scheme and the split two-step Milstein scheme, to solve stochastic differential equations (SDEs). Our results reveal that the two new schemes are strong convergent with order one. Moreover, with a restriction on stepsize, these two schemes can pres...

This paper is concerned with pth moment and almost sure exponential stability of the exact and numerical solutions of neutral stochastic delay differential equations (NSDDEs). Moment exponential stability criteria of the continuous and discrete solutions are established by virtue of the Lyapunov method. Then the almost sure exponential stability cr...

This paper establishes the boundedness, convergence and stability of the two classes of theta schemes, namely split-step theta (SST) scheme and stochastic linear theta (SLT) scheme, for stochastic differential delay equations (SDDEs) with non-globally Lipschitz continuous coefficients. When the drift satisfies one-sided Lipschitz condition with res...

This paper examines convergence and stability of the two classes of theta-Milstein schemes for stochastic differential equations (SDEs) with non-global Lipschitz continuous coefficients: the split-step theta-Milstein (SSTM) scheme and the stochastic theta-Milstein (STM) scheme. For \theta\in[1/2,1], this paper concludes that the two classes of thet...

This work focuses on regime-switching jump diffusions, which include three classes of random processes, Brownian motions, Poisson processes, and Markov chains. First, a scalar linear system is treated as a benchmark model. Then stabilization of systems with one-sided linear growth is considered. Next, nonlinear systems that have a finite explosion...

This paper examines exponential mean square stability of the split-step theta approximation and the stochastic theta method for the stochastic differential delay equations and stochastic ordinary differential equations (SODEs) under a coupled monotone condition on drift and diffusion coefficients. It is shown that for theta\in[0,1/2)� the two class...

Recently, explicit tamed schemes were proposed to approximate the SDEs with the non-Lipschitz continuous coefficients. This work proposes a semi-tamed Euler scheme, which is also explicit, to solve the SDEs with the drift coefficient equipped with the Lipschitz continuous part and non-Lipschitz continuous part. It is shown that the semi-tamed Euler...

This paper examines the relationship of choice of θ and mean-square exponential stability in the stochastic theta method (STM) of stochastic differential equations (SDEs) and mainly includes the following three results: (i) under the linear growth condition for the drift term, when θ ∈ [0, 1/2), the STM may preserve the mean-square exponential stab...

This work studies stability and stochastic stabilization of numerical solutions of a class of regime-switching jump diffusion systems. These systems have a wide range of applications in communication systems, flexible manufacturing and production planning, financial engineering and economics because they involve three classes of stochastic factors:...

Neutral differential equations have been used to describe the systems that not only depend on the present and past states but also involve derivatives with delays. This paper considers hybrid nonlinear neutral stochastic functional differential equations (HNSFDEs) without the linear growth condition and examines the boundedness and exponential stab...