Process actuator

The input/output units of the programmable controller constitute the interface between the PLC and the outside world. Hence, they are provided with the necessary signal conditioning functions which enable the PLC to be connected directly to the process actuators and transducers as desired. For this purpose the... 

In this chapter, an FD framework for batch chemical processes is developed, where diagnosis of sensor, actuator, and process faults can be achieved via an integrated approach. The proposed approach is based on physical redundancy for detection of sensor faults [38], while an analytical redundancy method, based on a bank of diagnostic observers, is adopted to perform process/actuator fault detection, isolation, and identification [4],... 

The above model includes the case in which a sensor and a process/actuator fault occur during the same batch operation. However, occurrence of multiple faults of the same nature (i.e., multiple process/actuator faults or multiple sensor faults), is not considered. 

Assumption 6.3 It is assumed that multiple process/actuator faults (i.e., two or more faults belonging to Ta occur) and multiple sensor faults (i.e., two or more sensors are subject to failures) cannot occur during the same batch operation. 

In the following, it is shown that multiple process/actuator faults (multiple sensor faults) can be detected but not correctly isolated and identified. 

On the contrary, occurrence of sensor and process/actuator faults during the same batch is allowed. 

Then, the healthy signal is used to feed a bank of /Vp + 1 nonlinear adaptive observers (where /Vp is the number of the possible process/actuator faults). The first observer is in charge of detecting the occurrence of process/actuator faults. The other /Vp observers, each corresponding to a particular type of process/actuator fault, achieve fault isolation and identification by adopting a suitable adaption mechanism. Figure 6.3 shows a block diagram representation of the overall architecture. 

The healthy measure, obtained via the diagnostic system described above, is used to feed a bank of observers providing process/actuator fault detection and isolation. One observer detects the occurrence of an actuator or process fault, while the other Np observers, each one corresponding to a fault type, are used for isolation and identification. 

Once a process/actuator fault has been detected, isolation and identification can be achieved via N-p nonlinear adaptive observers. Each observer is designed in such a way to be insensitive to a particular type of fault. In fact, the ith observer (hereafter i =, ..., Np) has the form... 

Hence, a sufficient condition for isolability for the Zth type of process/actuators faults is given by the two inequalities,... 

In order to make the observer (6.10) insensitive to process/actuator faults, the following modified dynamics can be adopted ... 

A control system consists of three parts a measurement a control algorithm and a process actuator. The process actuator (often a control valve) is always a direct user of energy the measurement may take energy from the process (as in the case of a head-type flow meter) and the control calculation never requires a significant energy supply. However, the correct control calculation is essential for energy-efficient operation of any process. 

An actuator is a functional element which connects the information processing part of an electronic control system in a technical of nontechnical process. Actuators can be used to control the flow of energy, mass or volume. The output quantity of an actuator is energy or power, often in the form of a mechanical working potential (force times displacement). The actuator control is always achieved using very low electrical power, ideally without any power consumption (Janocha 2004). 

The process productivity in grinding is described by the material removal rate Qw (Salje 1991). The material removal rate is a result of the process actuated values working engagement ae, feed velocity Vf, and back engagement ap and can be calculated for peripheral grinding by (see Fig. 1)... 

A Matlab-oriented view is proposed in figure 7, here the upper part shows the normal communication path, similar to sensor —> processing —> actuators, the lower part shows input values which are preprocessed by an external Electronic Control Unit (ECU). The middle... 

This book presents the recent developments in EAP material processing, actuator design, control-oriented modeling, and device and robotic apphca-... 

Instrumentation refers to all electronic, electrical, mechanical, or any kind of equipment used in a process for control purposes. That is, meters record the state of a process, actuators modify the control resources, and controllers command the action of the actuators. 

Data acquisition for process information, and the interface to process actuators, utilizes the simplest types of microprocessors, whereas the top level of the I C system hierarchy uses powerful minicomputers, eg., for core calculations. Intermediate types of microcomputers are utilized for control and operation, logic and signal treatment. 

Events or long alarm lists can be presented on the VDUs, but they are normally printed out in the adjacent recording room. Manual orders to process actuators and electric breakers are initiated by a sequence of keyboard and tracker ball actions. Normally, two manual actions are required for initiating a process actuation. 

The functionalities of smart textiles can be classified in five groups sensoring, data processing, actuation, communication, energy. 

The desire to have built-in sensing, processing, actuating, energy conversion and storage functions will require the identification of dynamic materials with chemical and physical properties that are readily manipulated. The ability to create these materials in different forms to enable integration into other structures will also be important. 

Output variables (driving signals for process actuators) are handled similarly Each control unit has command signals for all output signals belonging to the field units connected to it These output values are also stored in the real-time database for that unit... 

---