Other Input Types

Minimal-prototype controllers are designed for a specific type of input. A controller that is designed for a step change will perform quite differently if the change actually has some other shape. The following example illustrates the point. 

Example 20.4. Let s go back to the first-order lag process but now we will specify that the change in the setpoint is a ramp with a slope of one. 

Now we must specify the desired. It is unreasonable to expect that the controller could make the output be equal to the setpoint at the first sampling period because the controller will not see any error until this point in time. Remember the ramp setpoint started at zero at t = 0, so there was no error. Let us specify that the output 

With these specifications for JffJ and Jf, we can calculate the minimal-prototype controller for ramp setpoint changes using Eq. (20.15). 

Comparing this controller with that designed for a step input [Eq. (20.21)], we can see that the ramp setpoint design yields a controller that contains a double integrator. 

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The dynamic character measure (6) reduces to the residual sum of squares arising after fitting a first order model to actual plant step response data. This, of course, generalizes easily to the corresponding metric based on n -order positive real systems. While /.i D as presented involves the use of step-response information, other input types may be considered with the only alteration being the change in Eq. (7) to a finite-time norm in the case of persistently exciting inputs. 

The process controller is the master of the process-control system. It accepts a set point and other inputs and generates an output or outputs that it computes from a rule or set of rules that are part of its internal configuration. The controller output seiwes as an input to another controller or, more often, as an input to a final control element. The final control element is the device that affects the flow in the piping system of the process. The final control element seiwes as an interface between the process controller and the process. Control valves and adjustable speed pumps are the principal types discussed. 

Disadvantages Output not an exact linear reproduction of the input waveform, continuous current drain, efficiency not as good as that of other amplifier types... 

Platinum resistance thermometers are currently used by the NIST for calibration verification of other thermometer types for the temperature range 13.8 to 904 K. In addition, they are one of the easiest types of thermometers to interface with a computer for data input. On the other hand, platinum resistance thermometers are very expensive, extremely sensitive to physical changes and shock, have a slow response time, and therefore can take a long time to equilibrate to a given temperature. Thus, resistance thermometers are often used only for calibration purposes in many labs. 

The VL-Bus expansion card is also easily identifiable. The card is a bit longer than an ISA card and has one extra connector (the 32-bit, local connector). Figure 5.9 shows two typical VL-Bus expansion cards. These cards are typically used for video cards (as previously mentioned), SCSI host bus adapters, and multimedia expansion cards (sound cards, hard drive and CD-ROM controllers, and video input devices) because of the amount of throughput they need. Typically, you ll find no more than three VL-Bus connectors on a motherboard (mixed with other bus types). Any more than three and the processor wouldn t be able to keep up with the bus transfers. 

An undeveloped event represents an event where further development is either not possible or would serve no benefit. This event type is mostly used when the probability is already orders of magnitude smaller than other contributors to a gate, such that the gate probability is dominated by other inputs. It is therefore of no benefit to expend further effort in developing this part of the FT. 

Product extrinsic attributes 1. Source and history of milk and other inputs such as fodder, vaccination, type of cattle or buffalo, storage, handling and transportation conditions, etc. 2. Processing technology and resources used in production process of dairy products... 

Other errors (input type error/data range error). 

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