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Gangkai Li - IEEE Xplore Author Profile

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This brief considers the asymptotic tracking problem for a class of high-order nonaffine nonlinear dynamical systems with nonsmooth actuator nonlinearities. A novel transformation approach is proposed, which is able to systematically transfer the original nonaffine nonlinear system into an equivalent affine one. Then, to deal with the unknown dynamics and unknown control coefficient contained in t...Show More
The global fixed-time control problem is studied for uncertain nonlinear systems whose dead-zone input and control coefficients are unknown. Unlike the previous results, the control coefficients are unknown and their bounds are also not required. Firstly, a modified adaptive controller is proposed with the assistance of the adding a power integrator technique. And a logic switching mechanism is de...Show More
Embedded Image Coding provides a gradual improvement in the reconstruction of image as transmission proceeds. Designing of a successful embedded image compression algorithm involves the method of modeling and ordering in wavelet domain. A new embedded image compression algorithm Pixel Classification and Sorting (PCAS) is employed because of its effective and excellent compression performance. Wate...Show More
This paper deals with the leader-following consensus problem for a class of second-order multi-agent systems with unknown Lipschitz nonlinear dynamics. Moreover, the control coefficients are assumed to be identical and bounded but unknown. The Nussbaum gain function technique is employed to deal with unknown the control coefficients. It is proved that the states of the multi-agent systems can achi...Show More
This paper investigates the leaderless and leader-following consensus problem for a second-order multi-agent systems with input saturation, i.e., the control input is required to be priori bounded. Moreover, the control coefficients are unknown and cannot be lower or upper bounded by known constants. By virtue of adaptive control technique, Lyapunov theory, algebraic graph theory and Barbalat's le...Show More
In this paper, a stability control issue for a class of single-input single-output(SISO) time-varying nonlinear systems with mismatched uncertainties and completely unknown time-varying input coefficient is investigated. Combining with the so-called congelation of variables method and a special type of Nussbaum function, a backstepping-based adaptive control scheme was proposed in our paper, which...Show More
This paper introduces an innovative decentralized adaptive tracking control strategy designed for interconnected systems by input saturation and unknown control coefficient. Broad learning system (BLS), a novel nonlinear approximation technique, is utilized for the identification of the unknown function. Leveraging the properties of Gaussian function, the auxiliary dynamic system is introduced to ...Show More
The particular interest of this article is mainly focusing on the prescribed performance control (PPC) problem for a class of single-input single-output (SISO) nonlinear systems subject to serious mismatched uncertainties and unknown time-varying control coefficients. In contrast to most existing PPC works where the control coefficients are known or unknown while constant, the proposed control met...Show More
The issue of event-based asymmetric predetermined performance control (PPC) has been addressed for $p$-normal nonlinear systems with time-varying unknown control coefficients. A set of Nussbaum functions is introduced, capable of addressing both single and multiple unknown control coefficients. To achieve asymmetric PPC, a switching constraint scheme is proposed. Subsequently, an adaptive fuzzy co...Show More
This paper proposes fuzzy adaptive output feedback tracking control method for VTOL (vertical takeoff and landing) aircraft. Since uncertainties exist in the input coupling parameter due to its dependence on the physical parameters, and unknown disturbances can occur as well in the form of input-dependent accelerations in dynamics, which should be compensated at the same time. To this end, the dyn...Show More
This letter reports a model-free adaptive disturbance rejection control method for the surge velocity tracking of a robotic surface vehicle (RSV) in the presence of unknown external disturbances, internal dynamics, and control coefficient. Specifically, reduced-order and full-order filtering adaptive extended state observers (FAESOs) are proposed at first, for estimating the unknown control coeffi...Show More
In this paper, a new approach is successfully addressed to design the state-feedback adaptive stabilizing control law for a class of high-order nonlinear systems in triangular form and with unknown and nonidentical control coefficients, whose stabilizing control has been investigated recently under the knowledge that the lower bounds of the control coefficients are exactly known. In the present pa...Show More
In this paper, a numerical method for calibration of multiport reflectometers using matched load and a set of calibration loads having unknown reflection coefficients is proposed. The developed procedure has been validated by applying it to calibrate a wideband nine-port reflectometer operating over 2.5-3.5 GHz bandwidth. The obtained reflection coefficient measurements are very close to the resul...Show More
It is important to accurately calibrate the acoustic parameters of reference phantoms used in quantitative ultrasound (QUS) applications. However, laminate membranes used on the exterior of the phantoms complicate the attenuation coefficient (AC) measurements by introducing transmission loss. The existing through-transmission method addresses this issue by characterizing additional and separate me...Show More
The quantized feedback control is investigated for nonlinear feedforward systems with unknown control coefficients, unknown output functions and input quantization. The unknown output function is Lipschitz continuous but may not be derivable, the unknown control coefficients are assumed to be bounded, and the input quantization is logarithmic. By combining the backstepping method and the sector bo...Show More
This paper presents a filtering-based concurrent learning (FCL) adaptive control technique for a class of nonlinear systems with parameter uncertainties and unknown control coefficient. The proposed FCL builds on the baseline CL, which was created to achieve exponential convergence of either system parameters or control coefficient while relying on the estimation of state derivatives using numeric...Show More
This article addresses the tracking control problem of nonlinear pure-feedback systems, where the control coefficients and the dynamics of the references are unknown. Fuzzy-logic systems (FLSs) are used to approximate the unknown control coefficients and at the same time the adaptive projection law is designed to allow each fuzzy approximation to cross zero, which yields that the proposed method a...Show More
In this paper, an adaptive control scheme is designed for a class of strict-feedback nonlinear systems with unknown control coefficients. Unlike the existing iterative design approaches, we apply a fully actuated system approach to reduce the algorithmic complexity. First, the considered strict-feedback nonlinear systems are transformed into fully actuated systems by state transformations. After t...Show More
This paper studies the problem of adaptive fuzzy dynamic surface control (DSC) of nonstrict-feedback nonlinear systems subject to unknown virtual control coefficients, dead zone, and full state constraints. The Nussbaum gain technique is used to overcome the difficulty caused by the unknown virtual control coefficients. By utilizing the information of tan-type barrier Lyapunov function, the requir...Show More
This article considers an adaptive fuzzy control problem for nonstrict-feedback nonlinear stochastic systems, which contain input delay, output constraints, and unknown control coefficients, simultaneously. First, an original stochastic nonlinear mapping and the Pade approximation transformation techniques are developed to solve the symmetric output constraints and input delay. Then, an adaptive f...Show More
This paper focuses on regulation-triggered batch least-squares identifier based adaptive control for nonlinear systems with unknown control coefficients. Batch least-squares identifiers (BaLSI) are designed to estimate the unknown parameters, while a regulation-triggered condition is proposed to activate the BaLSI. Previous appeared excitation are stored and utilized for parameter updates at the t...Show More
This paper addresses the possibility of displacement measurement by microwave interferometry at an unknown reflection coefficient with the use of two electric probes mounted in a waveguide section. The aim of this paper is to show that the displacement measurement accuracy can be improved by using an interprobe distance other than its conventional value. The measurement error as a function of the ...Show More
In this paper, we studies the leader-following consensus for a class of uncertain nonlinear multi-agent systems (N-MASs) via switching learning control method. The novelties are reflected in the unknown input disturbances, unknown Lipschitz rate and unknown control directions. These unknowns make the consensus problem different from the existing related literature. To capture these unknowns, we pr...Show More
This paper proposes an adaptive tracking controller for stochastic nonlinear systems with unknown virtual control coefficients (UVCCs). Without using the Nussbaum gain technique (NGT), the controller is designed by employing an inequality, which requires much less complex computations. Novel adaptive controllers are constructed to compensate parameter uncertainties and UVCCs. To validate the effec...Show More
Detection of defects is a most important task in engineering subjects because a very tiny flaw in a structure might lead to a disaster at a later stage. In this paper, a novel, efficient and effective approach using guided ultrasonic waves for defect detection in pipeline structures is proposed. Based on boundary integral equations and Fourier transform of space-wavenumber domain, this developed m...Show More