Robust Compensation Control Research Articles

Adaptive actuator fault compensation for linear systems with matching and unmatching uncertainties

The problem of process systems subject to actuator faults (partial loss of actuator effectiveness) is considered. An active fault compensation control law is designed that utilizes compensation in a way that accounts for matching and unmatching uncertainties and the occurrence of actuator faults. The main idea is designing the robust compensation controller to guarantee closed-loop stability in the presence of faults, based on a neural network representation of the fault dynamics. Changes in the system due to faults are modeled as unknown nonlinear functions. The updating control law is derived such that all the parameters of the closed-loop system are bounded. An output feedback controller is used to the “healthy” system and the adaptive feedback controller is used to compensate for the effect of the dynamics caused by the fault. The advantage of fault compensation is the dynamics caused by faults can be accommodated online. The proposed design method is illustrated on a three-tank system.

Dynamic robust compensation control to inherent high-frequency motion disturbance on the electro-hydraulic load simulator

This paper focuses on a robust control method applied to an electro-Hydraulic Load Simulator (HLS) acting on a special aerodynamic load. Owing to the high-speed on-off valve, some pneumatic aircraft actuators have inherent high-frequency motion disturbance that reduces the dynamic tracking performance. Through combining velocity synchronising decoupling compensation and equivalent disturbance observers, this paper presents a Dynamic Robust Compensation (DRC) to achieve high precision load simulation. The experiments indicate that the velocity synchronising decoupling is used to restrain strong disturbance, whereas the robust compensator is adopted to reduce the remaining extraneous torque from motion flutter efficiently further.

Identification-based chaos control via backstepping design using self-organizing fuzzy neural networks

This paper proposes an identification-based adaptive backstepping control (IABC) for the chaotic systems. The IABC system is comprised of a neural backstepping controller and a robust compensation controller. The neural backstepping controller containing a self-organizing fuzzy neural network (SOFNN) identifier is the principal controller, and the robust compensation controller is designed to dispel the effect of minimum approximation error introduced by the SOFNN identifier. The SOFNN identifier is used to online estimate the chaotic dynamic function with structure and parameter learning phases of fuzzy neural network. The structure learning phase consists of the growing and pruning of fuzzy rules; thus the SOFNN identifier can avoid the time-consuming trial-and-error tuning procedure for determining the neural structure of fuzzy neural network. The parameter learning phase adjusts the interconnection weights of neural network to achieve favorable approximation performance. Finally, simulation results verify that the proposed IABC can achieve favorable tracking performance.

Robust control of switch-mode rectifier considering nonlinear behaviour

This work presents the disturbance observer-based robust current and voltage controls for a digital signal processor (DSP)-based boost-type switch-mode rectifier (SMR) considering nonlinear behaviour. First, a robust current control scheme is developed to let the SMR inductor current waveform closely track its command around zero-crossing points, and hence the SMR possesses improved line drawn power quality. Then a robust voltage two-degrees-of-freedom control (2DOFC) scheme and its systematic design approach are proposed. In determining the power circuit components and the key parameters of the proposed robust control schemes, the compromise between the desired performance and the nonlinear behaviours is considered. Specifically, the adaptation of voltage robust compensation control is made according to the observed nonlinear phenomena. Experimental results confirm that robust and good voltage tracking and regulation responses are obtained by the developed SMR. Furthermore, the developed SMR is successfully applied to serve as a front-end converter of a switched reluctance motor drive, and its effectiveness in vibration reduction and power quality improvement is demonstrated experimentally.

Switch-Mode Rectifier With Digital Robust Ripple Compensation and Current Waveform Controls

For a switch-mode rectifier (SMR), the inherent existence of a double frequency output voltage ripple renders the contradiction between the input current waveform and voltage regulation control performances. In this paper, the approaches for the ripple compensation and the improvement of input current waveform control of SMR are presented. First, a robust ripple compensation controller is developed, such that the effect of double frequency ripple contaminated in the output voltage feedback signal can be cancelled as far as possible. It follows that the current command yielded by the voltage control loop will be nearly ripple-free. Then a current control scheme, which consists of a feedback controller, a command feedforward controller and a robust disturbance feedforward controller, is proposed to let the SMR possess improved robust input current waveform control performance. Theoretical basis, design and implementation of the proposed controllers are described in detail. All the designed controllers are carried out digitally using DSP TMS320C240. The measured results indicate that under well-regulated dc output voltage, improved input current waveforms with high power quality are obtained by the proposed control approach, and the results are rather insensitive to input voltage and load variations.