Showing papers by "Xinkai Chen published in 2021"

Compound Adaptive Fuzzy Quantized Control for Quadrotor and Its Experimental Verification

Abstract: This article aims to realize a precise position and attitude tracking control for the quadrotor using a proposed fuzzy approximator-based compound adaptive fuzzy quantized control scheme. In the control scheme, a quantized output-feedback control for position tracking and a state-feedback quantized control for attitude trajectory tracking are combined to deal with the underactuated and strong coupling problems of the quadrotor. The main contributions are: 1) the adaptive fuzzy quantized control is realized, then the strong nonlinearities caused by the quantizer are effectively mitigated, which implies that the control precision can be improved when a low communication rate is required in the real-time control system of quadrotor; 2) by applying the adaptive fuzzy dynamic surface control (DSC) technique to the underactuated quadrotor control system, the “explosion of complexity” problem in the backstepping method is overcome and the $ {L}_{\infty }$ tracking performance is achieved with the proposed initializing technique inspired by Zhang et al. This guarantees that the attitude signals promptly converge to the desired trajectories, then the underactuated problem of the quadrotor is overcome by solving the designed adaptive fuzzy-quantized control equations; and 3) the experiments on the platform of the Quanser Qball-X4 quadrotor are conducted and the effectiveness of the proposed control scheme is validated.

Finite-time command filtered adaptive control for nonlinear systems via immersion and invariance

Abstract: This paper investigates the problem of finite-time adaptive output tracking control for strict-feedback nonlinear systems with parametric uncertainties. Command signals and their derivatives are generated by a new command filter based on a second-order finite-time differentiator, which attenuates the chattering phenomenon. The parameter estimations are achieved by an immersion and invariance approach without requiring the certainty equivalence principle. The finite-time adaptive controller is constructed via a backstepping design method, a finite-time command filter, and a modified fractional-order error compensation mechanism. The proposed control strategy guarantees the finite-time boundedness of all signals in the closed-loop system, and the tracking error is driven into an arbitrarily small neighborhood of the origin in finite time. Finally, the new design technique is validated in a simulation example of the electromechanical system.

Adaptive Pseudo Inverse Control for a Class of Nonlinear Asymmetric and Saturated Nonlinear Hysteretic Systems

Abstract: This paper aims at eliminating the asymmetric and saturated hysteresis nonlinearities by designing hysteresis pseudo inverse compensator and robust adaptive dynamic surface control (DSC) scheme. The “pseudo inverse” means that an on-line calculation mechanism of approximate control signal is developed by applying a searching method to the designed temporary control signal where the true control signal is included. The main contributions are summarized as: 1) to our best knowledge, it is the first time to compensate the asymmetric and saturated hysteresis by using hysteresis pseudo inverse compensator because the construction of the true saturated-type hysteresis inverse model is very difficult; 2) by designing the saturated-type hysteresis pseudo inverse compensator, the construction of true explicit hysteresis inverse and the identifications of its corresponding unknown parameters are not required when dealing with the saturated-type hysteresis; 3) by combining DSC technique with the tracking error transformed function, the “explosion of complexity” problem in backstepping method is overcome and the prespecified tracking performance is achieved. Analysis of stability and experimental results on the hardware-in-loop platform illustrate the effectiveness of the proposed adaptive pseudo inverse control scheme.

A Signal Compensation-Based Robust Swing-up and Balance Control Method for the Pendubot

Abstract: This article proposes a novel robust swing-up and balance control method using data-driven compensation signals for the Pendubot system, which is underactuated and subject to dynamic friction, backlash, and modeling uncertainty. The method involves three major developments. First, the uncertainty of the system is described by a previous sampled unknown nonlinear term and its changing rate. Compensation signals are then designed to eliminate the influence of the previous sampled unknown nonlinear term and its changing rate on the outputs of the controlled plant. Second, based on the Lyapunov stability theory, a robust swing-up control method is proposed. Third, in order to eliminate the limit cycle phenomenon caused by the uncertainty near the unstable equilibrium point, a proportional-derivative balance controller based on compensation signals is proposed. The stability and tracking error analysis show that the compensation signals can effectively eliminate the influence of dynamic friction, backlash, and modeling uncertainty on the system. Experimental results verify the effectiveness of the proposed method by showing significant improvements in production rate, accuracy, and cost.

A Switching Control Scheme With Increment Estimate of Unmodeled Dynamics

Abstract: This article presents a new switching control scheme for controlling a class of nonlinear discrete-time dynamical systems. The key idea behind the proposed control techniques lies in the decomposition of unmodeled dynamics, that is, the unmodelled dynamics are decomposed as a sum of a known function depending on the data from the posterior unmodeled dynamics measurement and an unknown increment. The control algorithm is based on a novel estimation algorithm for the increment of unmodeled dynamics, which contributes two nonlinear controllers. The theoretical results on both convergence and stability of the closed-loop system are given. The system performance is evaluated by some simulation results.

Piecewise Linear Control for Continuous-Time Markov Jump PWA Systems Based on Adaptive Fault-Tolerant Strategy

Abstract: This paper investigates the issue of piecewise-linear (PWL) control design for a class of continuous-time Markov jump piecewise-affine (PWA) systems based on adaptive fault-tolerant strategy. To solve the problem of switching path selection between different system modes and PWA regions, a new switching path selection (SPS) algorithm is proposed. Moreover, an efficient adaptive law is developed to ensure that the system remains stochastic stable even with actuator faults. By employing above methods and constructing the piecewise Lyapunov functional, a sufficient condition in the form of linear matrix inequalities (LMIs) can be obtained. Finally, a numerical example is given to illustrate the effectiveness of the proposed method.