Information about the Actuator Online
The internal failures of actuator online include failure of control unit, brake failure, failure of motor and drive unit and failure of mechanical transmission. The internal fault of actuator online may lead to abnormal operation of the electric actuators, which cannot correctly perform an action and will also damage other equipments in process control system and paralyze the process control system if it is a serious condition.
Combined with the actual maintenance experience, actuator online faults have the following characteristics: 1) the constitution of networked electric actuators is complex, a certain problems of which is difficult to be described by the mathematical model; 2) the same failure phenomenon may have a variety of causes, and the same reason for failure also may have different failure phenomenon; 3) the relationship between failure causes and failure phenomena of networked electric actuator has a certain regularity, so the experience of diagnosis and effective protection method can be summed up on the basis of the research, development, production and a lot of practice of personnel.
Actuator online fault diagnosis is realized by using the method of fuzzy information fusion, and then the actuator chooses the preset malfunction self-protection measures according to the output of the fault self-diagnosis. Actuator online fault diagnosis is based on a large amount of prior knowledge. According to the fault characteristic information and actuator preset operation parameters, the real-time accurate judgment of network anomalies in the working process of the electric actuator will be made by using fuzzy information fusion technology to provide decision-making basis for the real-time protection of networked electric actuator’s fault.
Since most of the work environment of pneumatic actuators is very bad, the actuator generally is in seal installation, therefore it is not easy to add new fault characteristic information acquisition unit. The fault characteristic information of pneumatic actuators mainly comes from all kinds of equipment information and status signal contained by the actuator online itself during the operation of equipment, such as the motor temperature, working current, rotor speed and position sensor output value, semaphore, runtime, letters between data package, etc.
The cause of the problem reflected by each kind of fault characteristic information of actuator online is different, and the correlation degree between each other is also different. Since the networked electric actuator may occur more failures with large scale of knowledge, but on the other hand, network fault characteristics of the electric actuator after dealing with the information fusion can directly be inferred, so this article applies the rules of the expert system for fault diagnosis, considering the network real-time electric actuator fault diagnosis and protection. Rule-based expert system reasoning machine compares the facts (fault feature information of melting results) with the precondition of rule in the knowledge base (the default) and activates relative rules to obtain evaluation results from expert system.
To improve the real-time network pneumatic actuators fault self-diagnosis, knowledge base of expert system needs to be combed, simplified to get clear rules so that the program of micro processing unit of networked electric actuator can be realized. The combination of networked electric actuator fault characteristic information fusion and rule-based expert system greatly simplifies the number of rules in the knowledge base of expert system, providing guarantee for the realization of the real-time fault diagnosis.