BASIC TERMINOLOGY IN PROCESS CONTROL
Set Set is change the flow of mass, energy or information through
elements or actuators control (definition, see DIN 19 226) . Algorithm An algorithm is a finite sequence of instructions completely defined, which, from a reliable variables, generates the output variables that are desired
.
control algorithm
A control algorithm formally describes the control strategy, in the simplest case may take the form of equation a controller. In general, an algorithm performs calculation processes in sequence, according to a specified schema.
maximum amplitude overshoot
maximum overshoot amplitude xm is the largest deviation from the steady-state value of the step response after
first time exceed the limits of a tolerance zone oscillations. Country
features
In a field of features characteristic curves represent the transfer elements with multiple steady states and several input variables, according to an input variable, for different values \u200b\u200bof uR other input variables to their steady states. Case
stability limit
describes a control system as stable in the limit, if the system's operation is presented exactly at the boundary between stable and unstable.
derivative action coefficient
transfer element D (derivative action item) is a functional component with a transfer characteristic defined by:
where KD is the constant coefficient called derivative action.
integral action coefficient
transfer element type I is a functional module with the following transfer characteristic:
where KI is the constant called integral action coefficient. Its inverse is called the integration time constant TI = 1/KI.
proportional action coefficient
transfer element type P (proportional action item) is a functional module with the following transfer characteristic: comparison
The comparator is the functional unit that generates the error signal e , from the reference variable w and the feedback variable r. 
time constant The time constant T of a linear system of first order is a speed measurement system response. This indicates the lapse of time from which feeds a step function in the input until the output variable
system reaches 63% of its final value steady. N order systems have correspondingly n time constants.
integration time constant
The integration time constant TI is a parameter characteristic of the element type I. Taking the inverse function, we obtain the integral action coefficient KI. Automatic
"The automatic control is the process by which successive Registers controlled variable (controlled variable) and compared with another variable named
reference variable, so that the result of the comparison to compensate for the difference to the reference variable "(extract from the standard: DIN 19 226 Part 1 , issue 05.84). The sequence of control actions occur in the closed loop control system.
Control fixed reference value
A control system with fixed reference value is the type of control that reference variable is set to a fixed value.
Control with variable reference value
A control system with variable reference value is the type of control that the current value controlled variable is the change of the reference variable.
continuous-time Control
The continuous-time control is recorded continuously variable controlled and compared with the reference variable.
split-range control
split-range control is a control process in which the driver has different characteristics depending on the error signal is positive or negative.
Controller Driver is a functional unit composed of a comparator element and error correcting device.
adaptive controller adaptive controller is controller whose parameters are continuously adapted to the current parameters of the controlled system.
Two-position controller
two-state controller employs a transfer element
two positions as a controller.
digital controller
A digital controller is a controller based on digital technology, which processes discrete-time signals, using an algorithm implemented as software and stored in the controller.
Controller I type I
A driver is a Type I transfer element used as a controller.
Driver P
P-controller is a P-type transfer element used as a controller. PD controller
PD type controller consists of a P-controller and controller type D connected in parallel.
PI controller PI controller consists of a P-controller and an I connected in parallel. PID Controller
PID controller consists of a P-type controller, a controller type I and type D controller connected in parallel. PID-controller
T1-T1 PID controller is a PID controller where the D-type component is retarded (ia ** PT1 is filtered).
main controller main controller is designated as the controller of the external branch of a cascade control. Characteristic
If transfer element with a variable input and output variable has different steady states at each fixed value of uR carries a fixed value of vR in the respective steady. The representation of the dependence of vR and uR values \u200b\u200bcalled characteristic curve.
curve characteristic of a controlled system
The characteristics of a controlled system is the ratio between corrective variable and input variable and output variable x of the controlled system in steady state, for a given value of the disturbance variable.
static characteristic curve
Phase Shift
The phase shift or phase shift is defined as the phase angle that occurs
between output variable and input variable of a linear system stimulated by a sinusoidal signal. The phase shift is, among other things dependent on the frequency.
Bode diagram Bode diagrams are a graphical representation, in logarithmic scale, the amplitude characteristic
or gain and phase of a linear system.
Nyquist polar plot
The polar diagram Nyquist plot represents a linear system and simultaneously the magnitude and phase in the complex plane of a function, having the angular frequency w as a parameter of the curve.
Direct Digital Control Direct Digital Control is called (DDC) to a control system equipped with a digital controller.
error correction device
The error correcting device is a functional unit, which is fed as input variable, the error signal and leaving the comparator, giving rise to a controller output variable follows variable reference to quickly and accurately, even under the effect of disturbance variables.
Device adaptation
The adapting device is the component in a circuit of closed loop adaptive control, determines the set of controller parameters based on the variables of a controlled system and are transferred to the controller.
final control device
final control device is a functional unit composed of the control unit final and final control elements.
final control element
final control element is a functional unit that is located at the entrance of the controlled system, forming part thereof, and acting on 
flow of mass or energy. Its variable corrective entry is the variable. Element
transfer of two positions
transfer element two positions is a functional unit with the following transfer characteristic: where
Us> = 0. Element
transfer of three positions
The element of transfer of three positions is a functional module with the following transfer characteristic: where Us1
<0,> 0. The difference Us2-called dead zone Us1 Ut.
transfer element type D
transfer element D (differential action item) is a functional component with a transfer characteristic defined by:
where KD is the constant coefficient called derivative action.
type I transfer element
transfer element type I is a functional module with the following transfer characteristic:
break frequency
break frequency is called the angular frequency of a PT1 element type in the extent that the gain decreases by 3 dB with respect to the stationary gain. The break frequency corresponds exactly to the inverse of the time constant transfer element.
step function signal is a test in which the amplitude at an instant t0 change abruptly from one value constant to another constant value. Gain critical
KPkrit
critical gain is the ratio of proportional action the controller, in which the system works in closed loop control in the stability limit (continuous oscillation).
amplitude gain gain scale
As defined the relationship between the amplitudes of the output and input of a linear system stimulated by a sinusoidal signal. The amplitude gain is, among other things, frequency dependent. Instability
is said that a controlled system, or a control system is unstable, if the output variable does not tend to a steady final value when feeding the system with a finite change in the reference variable or a disturbance variable. Structural instability
is said that a control system has a structural instability when necessarily an unstable behavior, regardless of the settings of the parameters of the controller. Structural instability can only be countered by choosing another type of driver.
phase margin phase margin is the angular distance between the point corresponding to the frequency of zero dB crossing on the phase response curve of open loop and parallel to the frequency axis passing through the phase value of - 180 °. Method
tangent passing through the turning point
This method draws a tangent from the point of inflection in the curve of step response of the controlled system and then determine graphically the gain of the controlled system KS, the Your time and time delay compensation Tg (controlled systems with compensation). From these characteristic parameters determining the controller. Branching node
A branching node is a point on a functional diagram of where it leaves a variable to other blocks, or even where they feed and add other variables. Is represented as a point.
Optimization Under the concept of optimization is a set of measures to achieve that, under certain conditions, obtain, if possible, state control process in accordance with the rates of efficiency, whether the values \u200b\u200bobtained larger or smaller (see also DIN 19 236)
system Order
The order parameter of the system is a basic characteristic of a dynamic system. Is given by the number of independent energy storage up the system. Parameters
system parameters the system are variables whose values \u200b\u200bdetermine system behavior for a given structure. Critical period 
Tkrit
The critical period is the period of permanent oscillation occurs in a control system when it is at the limit of stability. Disturbance
A disturbance variable z is an external variable that affects the automatic control action or regulatory action desired.
Process A process is a set of procedures operating in a transforming, transporting or storing materials, energy or information.
Point operation
The operating point is the point on a curve or over a field of characteristic curves, in which the transfer element is working.
Rules
controller parameterization rules controller parameterization (design formulas ") are the design rules for PID controllers, which are usually defined in terms of certain characteristic parameters of controlled systems, such as for example the delay time or compensatory time (reaction time).
Regular Regular is the procedure or process that occurs in a system over one or more variables as input variables, other variables affect output, conditioned by the intrinsic properties of the system (extract from DIN 19 226 Part 1, Draft 03.84). The regular action can be both a functional branch opened as a closed, on which the input variables that influence the output variables do not influence on about themselves.
Response to the reference variable
The response to the reference variable is the characteristic that describes the behavior of the control system under the effect of the reference variable.
response to shocks
response to disturbance is the control system behavior under the stimulus of a disturbance variable.
step responses
The step response is the temporal response curve of the output variable is obtained with a step function input variable. Response
ramp to a ramp response is the temporal behavior of the output variable, when fed at the entrance ramp function with a variation of speed. 
Response to a sinusoidal signal
The response to a sinusoidal signal is the temporal behavior of the corresponding output variable a variable input with a sinusoidal function at steady state.
steady-state response
Named static behavior of a system, ie the behavior of the system output variable, corresponding to a change in the input variable, after the transitional regime is finished. Indicial response
If the step response ratio is on level footing with the input variable, one obtains a relative step response, which is called the indicial response h (t). Transient response
represents the dynamic behavior of a system, ie the transient behavior of the output variable of the system to a variation of the input variable.
Sensor The sensor is a measuring device that converts a physical variable (eg temperature or pressure), in another more suitable for further processing (in most cases, as an electrical signal or voltage .)
error signal
error signal e is the difference between the reference variable w and the feedback variable r.
permanent error signal
If the current value of a control system, after completion of the transitional regime not exactly equal to the desired value, the system presents a permanent error signal is represented by eb.
test signal
A test signal is supplied, for example, a controlled system or a system of control, for, from the behavior of the system output signal, draw conclusions about the characteristics of the system or making evaluations of the same. The typical test signals are the step function, ramp function or a sinusoidal signal
.
System A system is, from the point of view of logical relations, an array of interrelated objects. The arrangement is bounded in accordance with certain assumptions about their environment. 
compensated system
A compensation system is a system or plant whose output variable tends towards a new steady state value when a change of variable correction.
controlled system is the system to be controlled, ie is the process which acts on the control loop (eg an electric motor in which you want to control the speed).
P-controlled system
A P-controlled system is the system that is equipped with only the proportional-action feature, ie no delay (system of order 0).
controlled systems with delay
delay controlled systems are systems that do not react immediately to changes in the input variable but with a certain delay. Only P-type transfer elements have no delays.
cascade control system
A cascade control system is a control system with one or more auxiliary overlapping loops, ie a control system which, together with the final controlled variable, there are several variables intermediate controlled systems.
cascade control system
A cascade control system is a system without feedback control, ie, a serial connection of several blocks of transfer elements.
controlled system or plant
briefly refer to a controlled system in open loop or closed loop.
regulated system
is the process or system which acts to regulate (eg a motor).
without compensation system
A system without compensation is a system or plant whose output variable does not tend to a steady state value when a change in the variable correction, but continues to change constantly.
Derivative time
action time Tv derivative is a characteristic parameter of a PD type controller. Is the length of time required for the response to a ramp function of a PD type controller reaches a specified value before it had reached only due to its P-type component
Integral time
controller integral action time Tn driver is a parameter of the PI. Is the length of time required to obtain a corrective change in the variable equal to that obtained with only one controller type P, stimulating the system with a step function.
overshoot rise time
rise time overshoot So is the time lag from time to until the step response reaches the limit of the tolerance zone. Settling time
Taus The settling time is the time interval that elapses from the instant to, until the step response remains within the tolerance band.
settling time compensation time Tg is the time interval between the intersection of the first turning point of the step response in x-axis and the intersection of the parallel to the x-axis defined by the steady-state value. Sampling time
Weather sampling is the time lag between two instances in which samples are taken in the control. Delay time
Your time is the delay time between the point to and point of intersection with the horizontal axis of the first tangent through the point of inflection of the curve of step response . to is the moment when the step is fed to the input of the system. Downtime
View Tt type transfer element. 
final control unit
final control unit is the functional unit in which variable from the controller output variable is generated for necessary corrective action the element of ultimate control.
desired value The desired value of the controlled variable is the present value of the reference variable.
real value is the present value of the controlled variable. Variable controlled
The controlled variable x is the output variable of the controlled system, which is fed as input signal to a sensor device to register in order to control it. Variable is the controlled system output and input of the measuring device. Variable
corrective and remedial variable is the output variable control device (open loop system) or device system controller (closed loop system), and is, at the same time, the input variable of the controlled system. Action serves to transfer control to the controlled system.
Variable input
The input variable u is a variable that acts on the system observed, without influencing the system variable. A set of input variables ui i = 1, 2, 3 ... p of a system is an input vector u = (u1, u2, u3 ... up). Variable
disturbance
A disturbance variable z is an external variable that affects the automatic control action or regulatory action desired.
Variable feedback
The feedback variable r is obtained by recording the controlled variable and fed her to the comparator. Variable output
v The output variable is the variable of a system that can be recorded and only depends on the system itself and the input variable. A set of output variables vk, k = 1, 2, 3 ... q, a system considered is an output vector v = (v1, v2, v3 ... vq).
controller output variable
The controller output variable and R is the input variable adjustment device. Variable reference
The reference variable w of control system, open or closed loop, is a variable that is fed externally to the system and is not influenced by it. In both cases, the system output variable is to changes in the reference variable.
Variation of parameters Variation of parameters are the changes that occur in a controlled system parameters (eg, gains or time constants) while the system is in operation.
tolerance zone
The tolerance zone is the difference between the conditions that have established themselves as upper and lower deviation with respect to the stationary value of the response a step. Usually expressed in%.
