Honglei Xu

Exponential Stability With

In this technical note, we consider exponential stability and stabilization problems of a general class of nonlinear impulsive switched systems with time-varying disturbances. By using the switched Lyapunov function method, sufficient conditions expressed as algebraic inequality constraints and linear matrix inequalities are obtained. They ensure that the nonlinear impulsive switched systems are not only exponentially stable but also satisfy the L2-gain condition. Based on the stability results obtained, an effective computational method is devised for the construction of switched linear stabilizing feedback controllers. A numerical example is presented to illustrate the effectiveness of the results obtained.

L_{2}

In this paper, stability criteria of impulsive switched systems with time-invariant delays are introduced. We proposed a class of impulsive switched systems with time delays and parameter uncertainties. Based on the result of Theorem 3.1 in [X.Z. Liu, G. Ballinger, Uniform asymptotic stability of impulsive delay differential equations, Computer and Mathematics with Applications 41 (2001) 903-915], sufficient stability conditions of the impulsive delay switched systems are obtained. The validity of the results is shown by an example and its simulation.

-Gain Condition of Nonlinear Impulsive Switched Systems

In this paper, we study the problem of robust H infinite stabilisation with definite attenuance for a class of impulsive switched systems with time-varying uncertainty. A norm-bounded uncertainty is assumed to appear in all the matrices of the state model. An LMI-based method for robust H infinite stabilisation with definite attenuance via a state feedback control law is developed. A simulation example is presented to demonstrate the effectiveness of the proposed method.

Delay independent stability criteria of impulsive switched systems with time-invariant delays

This paper studies the problem of global exponential stability and exponential convergence rate for a class of impulsive discrete-time neural networks with time-varying delays. Firstly, by means of the Lyapunov stability theory, some inequality analysis techniques and a discrete-time Halanay-type inequality technique, sufficient conditions for ensuring global exponential stability of discrete-time neural networks are derived, and the estimated exponential convergence rate is provided as well. The obtained results are then applied to derive global exponential stability criteria and exponential convergence rate of impulsive discrete-time neural networks with time-varying delays. Finally, numerical examples are provided to illustrate the effectiveness and usefulness of the obtained criteria.

Robust H infinite stabilisation with definite attenuance of an uncertain impulsive switched system

Abstract In this paper, the sampled-data control is applied to synchronize chaotic neural networks subject to actuator saturation. By employing a time-dependent Lyapunov functional that captures the characteristic information of actual sampling pattern, we derive a local stability condition for the synchronization error systems. By this condition, we design a sampled-data controller to regionally synchronize the drive neural networks and response neural networks subject to actuator saturation. Moreover, an optimization method is given to design the desired sampled-data controller such that the set of admissible initial conditions is maximized. A numerical example is given to demonstrate the effectiveness and merits of the proposed design technique.

Global exponential stability of impulsive discrete-time neural networks with time-varying delays

This paper presents a tracking control with guaranteed prescribed performance (PP) for space free-flying robots with uncertain kinematics (Jacobian matrix) and dynamics, uncertain normal force parameter, and bounded disturbances in a compliant contact with a planar surface. Given the orientation of the surface and a nonlinear model of the elastic force, a controller is designed requiring no information on the robot parameters and the disturbances. This controller will guarantee that the tracking errors satisfy PP indexes such as the maximum steady-state errors and overshoots, and the minimum convergence rates. Thus, contact maintenance can be ensured as prescribed. An approximation of the Jacobian is utilized in the presence of uncertain robot kinematics, and PP position/attitude tracking of the free-flying base is achieved in addition to the PP force/position tracking of the manipulators fingertip. The proposed controller is based on an error transformation technique, and a directly tunable gain for the transformed error feedback is introduced in the control to trade off between the tracking performance and control effort. Numerical simulations and comparisons demonstrate the effectiveness and superiority of the proposed controller. A novel force/position tracking controller is proposed for space free-flying robots.Prescribed tracking performance is guaranteed through an error transformation.No information on robot parameters and bounded disturbances are required.Kinematical uncertainty of the robot is handled by approximation of Jacobian.A tunable gain is introduced to trade off between control performance and effort.

Sampled-data synchronization control for chaotic neural networks subject to actuator saturation ☆

Kallmann syndrome (KS) is a genetically heterogeneous disease characterised by hypogonadotrophic hypogonadism in association with anosmia or hyposmia. This condition affects 1 in 10 000 men and 1 in 50 000 women. Defects in seventeen genes including KAL1 gene contribute to the molecular basis of KS. We report the clinical characteristics, molecular causes and treatment outcome of two Chinese brothers with KS and X‐linked ichthyosis. The phenotypes of the patients were characterised by bilateral cryptorchidism, unilateral renal agenesis in one patient but normal kidney development in another. The patients had low serum testosterone, follicle‐stimulating hormone and luteinising hormone levels and a blunt response to the gonadotrophin‐releasing hormone stimulation test. After human chorionic gonadotrophin treatment, the serum testosterone levels were normalized, and the pubic hair, penis length and testicular volumes were greatly improved in both of the patients. The two affected siblings had the same novel deletion at Xp22.3 including exons 9‐14 of KAL1 gene and entire STS gene. Our study broadens the mutation spectrum in the KAL1 gene associated with KS and facilitates the genetic diagnosis and counselling for KS.

Adaptive Jacobian force/position tracking for space free-flying robots with prescribed transient performance

In this paper, we consider the practical set stability problem of a switched nonlinear system, in which every subsystem has one unique equilibrium point and these equilibrium points are different from each other. Based on the new concepts such as ε-practical set stability and a τ-persistent switching law, we explicitly construct a closed bounded set Γ and prove that under an appropriate τ-persistent switching law the switched system is ε-practically (asymptotically) set stable with respect to Γ. Finally, we present a numerical example to illustrate the results obtained.

Novel homozygous deletion of segmental KAL1 and entire STS cause Kallmann syndrome and X-linked ichthyosis in a Chinese family.

In flotation processes, concentrate grade is the key production index but is difficult to be measured online. The mechanism models reflect the basic tendency of concentrate grade changes but cannot provide adequate prediction precision. The data-driven models based on froth image features provide accurate prediction within well-sampled space but rely heavily on sample data with less generalization capability. So, a hybrid intelligent model combining the two kinds of model is proposed in this paper. Since the information of image features is enormous, and the relationship between image features and concentrate grade is nonlinear, a B-spline partial least squares (BS-PLS) method is adopted to construct the data-driven model for concentrate grade prediction. In order to gain better generalization capability and prediction accuracy, information entropy is introduced to integrate the mechanism model and the BS-PLS model together and modify the model output online through an output deviation compensation strategy. Moreover, a slide window scheme is employed to update the hybrid model in order to improve its adaptability. The industrial practical data testing results show that the performance of the hybrid model is better than either of the two single models and it satisfies the accuracy and stability requirements in industrial applications.

New results on practical set stability of switched nonlinear systems

This paper is concerned with the boundedness and attractiveness of nonlinear switched delay systems whose subsystems have different equilibria. Some sufficient conditions which can guarantee the system’s boundedness are obtained. In addition, we work out the region where the solution will remain and furthermore the relationship between the initial function and the bounded region. Based on the new concept of attractor with switching laws, we show that the nonlinear switched delay system is attractive and then obtain the attractive region.