Safety Diagnosis And Fault Tolerant Control Base On Hybrid Model

Hybrid system has discrete and continuous dynamic characteristic.These two parts of the system interact with each other.Modeling and control of hybrid system become focus and difficulty problems in control science and control engineering.Based on hybrid MLD theory,this dissertation improves the automatic modeling method of MLD model.Active fault diagnosis and safety prediction algorithm using formal verification is proposed.Fault tolerant control strategy with zone predictive control is studied.The above issues are simulated on a three tank benchmark problem.Simulation result shows the effectiveness of the algorithm in this dissertation.The main content of this dissertation includes the following aspects.This dissertation improves the automatic modeling method of MLD model.The manual modeling method and automatic modeling method is studied.HYSDEL tool can build MLD model automatically.It makes the process of MLD modeling simple to use.But the dimension of automatic model is significantly more bigger than manual model.The improved method improves the modeling efficiency of the MLD model.Then the algorithm has been verified on automatic modeling of saturation system.Active fault diagnosis and safety prediction based on formal verification is proposed.Based on formal verification,a process can be driven from the region that can't be diagnosised to a fault or a normal region by applying exciting signal.Using safety diagnosis model of hybrid system,the unsafe state is defined as reach set.The reach possibility of dangerous state set is calculated and judged.The safety problem in system is transformed to formal verification problem using hybrid formal verification method.Active fault diagnosis and safety prediction has been verified on three tank control problem.Simulation result verifies the effectiveness of the method this dissertation investigated.This provides a new way to solve the safety problems of hybrid system.Fault tolerant control strategy with zone control is studied.This paper introduces zone control strategy into fault tolerant control.It uses logical variable to predict the zone of system sate.Then the corresponding control program is applied to the target zone.Fault tolerance control scheme can be realized by zone control algorithm.The simulation result of three tank control shows that the hybrid system fault tolerant control strategy can make the system recover to the small deviation zone more faster.