Adaptive Dynamic Output Feedback Control Research Articles

New Adaptive Dynamic Output Feedback Control of Double-Pendulum Ship-Mounted Cranes With Accurate Gravitational Compensation and Constrained Inputs

Output feedback control without using velocities is an effective way of dealing with problems caused by unmeasurable velocities and noise magnification by numerical difference, which are practical issues associated with crane control. This article proposes a new adaptive dynamic output feedback control approach for double-pendulum ship-mounted cranes in the presence of unknown parameters (e.g., cargo masses). The problems caused by the unknown masses are addressed through a new adaptive gravitational compensation law. Also, the input constraints are tackled by introducing bounded functions. Specifically, to handle the complicated disturbances caused by ship motions, new state variables are constructed to transform the dynamic model. Then, Lyapunov-based stability analysis is proceeded to design the controller and the adaptive law. To the best of authors’ knowledge, this is the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"/> first <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"/> control method proposed for double-pendulum ship-mounted crane systems <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"/> without <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"/> using velocity signals, which can simultaneously eliminate steady errors, suppress unexpected cargo swing, achieve accurate gravitational compensation, and satisfy input constraints. The closed-loop system’s state variables asymptotically converge to the equilibrium point, which is rigorously proven. A series of experiments are implemented on a hardware testbed, which further illustrate the satisfactory performance of the proposed method.

Adaptive Dynamic Output-feedback Control for Chemical Continuous Stirred Tank Reactor System with Nonlinear Uncertainties and Multiple Time-delays

This paper addresses the dynamic-output-feedback control problem for a class of nonlinear system with nonlinear uncertainties and multiple time-delays. Compared with the previous work, the time delay parameters of the system are both multiple and time-varying, and the results are further extended to the chemical continuous stirred tank reactor (CSTR) case. First, the system is decomposed into two subsystems based on the output and input matrix. Secondly, a dynamic compensator is designed for the first subsystem, and the output feedback controller is further employed based on the second subsystem and the compensator. Moreover, by using the introduced LyapunovKrasovskii functional, it can be seen that the solutions of the resultant closed-loop system converge to an adjustable bounded region. In this paper, the uncertainties are in the nonlinear form and bounded by nonlinear functions with unknown gains. And the control design conditions are relaxed because of the developed dynamic compensator. Finally, the simulations for a chemical (CSTR) case are performed to show the effectiveness of the main results.

Dynamic Output Feedback Control for Nonlinear Uncertain Systems with Multiple Time-Varying Delays

This paper addresses the adaptive dynamic output-feedback control problem for a class of nonlinear discrete-time systems with multiple time-varying delays. First, the guaranteed cost function is introduced for the nonlinear system to reduce the effect of the time-varying delays. Secondly, in order to deal with the multiple time-varying delays, the nonlinear system is decomposed into two subsystems. Then the compensator is designed for the first subsystem, and the adaptive dynamic output-feedback controller is constructed based on the subsystems. By introducing the new discrete Lyapunov-Krasovskii functional, it can be seen that the solutions of the resultant closed-loop system converge to an adjustable bounded region. Finally, the simulations are performed to show the effectiveness of the proposed methods.

H∞ control for Markovian jump systems with partially unknown transition rates via an adaptive method

This paper investigates the problem of the H∞ control for a class of continuous-time Markovian jump systems with partially unknown transition rates. An adaptive H∞ performance index is defined to describe the disturbance attenuation performance of Markovian jump systems. By combining the linear matrix inequality (LMI) approach for designing H∞ controllers and the adaptive method for estimating the unknown terms, a new method for designing the H∞ controllers is proposed, where an estimation of the transition rate matrix is given and the controller parameter matrices are dependent on the known transition rates and the estimations of the unknown terms. The sufficient conditions for the existence of the adaptive state feedback controller and the adaptive dynamic output feedback controller are proposed and the estimations of the unknown transition rates are obtained from the adaptive laws. It is shown that the proposed adaptive controllers provide better performance than the traditional fixed gain controllers. A practical example is provided to illustrate the effectiveness and advantage of the proposed method.