Hydraulic pitch-controlled system is one of the components of wind turbines which are frequently prone to faults. Early fault prediction of the pitch control system can improve the operation reliability effectively and reduce the unnecessary loss. Wind turbines suffer much environmental interference; moreover, data-based fault prediction is vulnerable to occur false alarms by the impact of these factors. And it is difficult to implement the fault isolation.
So this paper presents a fault prediction method for the pitch-controlled system, which is based on the mathematical model of wind turbines physical properties. The residual root mean square (RMS) is used as residual evaluation function.
In the end of the paper, by the simulation using the hydraulic pitch actuator fault as the example, the effectiveness of the proposed fault prediction scheme is verified. Abstract: Highly maneuverable aircraft has redundant electrohydraulic actuators that generate theforces to drive the aircraft control surfaces. Two problems are important in these actuators. First,during reconfiguration of the actuator channels the hydraulic system works in the full range of itsparameters. It leads to strongly nonlinear models of the redundant servo.
Second, the frequencybandwidth of elements, which are located in the feedback loop of the servo, should be as wide aspossible. Therefore, it is necessary to choose proper control method for actuator, where thecontroller of control system adjusts the set point signal. The advanced control methods can ensurethe new quality of the systems.The new, advanced methods can cope with such problem in practical applications. There areavailable: adaptive methods, predictive methods, etc. And first of all, the robust control methods.These methods are robust on external disturbance. The causes of disturbances are very different: theinaccuracy in the mathematical and simulation model, the change of the operation point, theweather and temperature conditions, etc.
We have designed such models in the Matlab/Simulinkenvironment and we divided the full actuator into small subsystems. Abstract: In order to detect and isolate orbiting satellite actuator faults, a decoupling parity space method was extended. The decoupling parity vector was obtained using this method by singular value decomposition. Sometimes this vector may not exist, then by singular value substitution or generalized Eigen value method was used for solving the optimal approximation. The vector can easily make satellite actuator fault detected and isolated. The simulation results showed the effectiveness of the proposed algorithm.
Abstract: Base on the Lyapunov stability theory, an improved suboptimal control system scheme is advanced in this paper. Aiming at hypersonic reentry vehicle nonlinear properties of the actuator deflection angle rate and the deflection angle were studied. First, the mathematical model of the control system is established according to the flight control system control scheme.
We certainly have the design tools to overcome these nonlinear effects, but the market dynamics present challenges to any company developing the necessary technology. Hydraulic wind turbines.
Considering the project realize easy, the flight control system is designed based on suboptimal control of Lyapunov stability theory. In order to close to the optimal control, then the suboptimal control design is improved. Finally the controller is applied to the instances, by analyzing the results confirmed the method is correctly. Abstract: In order to accelerate the velocity and improve the accuracy of the pseudo-dynamic testing,the external displacement control method is put forward based on the hardware control. The internal displacement sensor of the actuator is invalid on control and substituted by the LVDT displacement sensor connected with the specimen.
The process of the feedback displacement and command error compensation is quickly implemented by the internal closed-loop control of the actuator. Compared with the iteratively approximate load control, this method not only makes the testing velocity fast, but also enables the error between command and feedback to be “zero”. The fast pseudo-dynamic testing about a cantilever beam is carried out by applying appropriate PID parameters of the actuator. The testing result shows that although this method has rather high requirements in the control system and electro-hydraulic servo load device, and the risk to some extent, the fast response of the actuator can be firmed by applying appropriate PID control parameters.
This method provides a fast testing technology for velocity-dependent structures or specimens. Abstract: This paper describes the application of system identification techniques and robust control strategies to a pneumatic muscle actuator system. Due to the inherent nonlinear and time-varying characteristics of this system, it is difficult to achieve excellent performance using conventional control methods.
Therefore, we apply identification techniques to model the system as linear transfer functions and regard the un-modeled dynamics as system uncertainties. Because robust control is well-known for its capability in dealing with system uncertainties, we then apply robust control strategies to guarantee system stability and performance for the system. This work is carried out in three parts. First, the pneumatic muscle actuator system was modeled as linear transfer functions. Second, robust control theorem were utilized to design a Hinf robust controller to deal with system uncertainties and performance requirements. Finally, the designed controller was implemented for experimental verifications and compared with a conventional PID controller. From the experimental results, the proposed Hinf robust controller is deemed effective.