1、Absolute stabilityA system description that reveals whether a system is stable or not stable without consideration of other system attributes such as degree of stability. 312Actuator The device that causes the process to provide the output; the devices that provides the motive power to the process.A
2、ll-pass networkA nonminimum phase system that passes all frequences with equal gain.BandwidthThe frequency at which the frequency response has declined 3dB from its low-frequency value.Block diagramUnidirectional, operational block that represents the transfer functions of the elements of the system
3、.Automation The control of an industrial process by automatic means.Bode plotThe logarithm of magnitude of the transfer function is plotted versus the logarithm of omiga, the frequency. The phase, phi, of the transfer function is separately plotted versus the logarithm of the frequency.Canonical for
4、m A fundamental or basic form of the state variable model representation, including diagonal canonical form, Jordan canonical form.Characteristic equation The relation formed by equating to zero the denominator of a transfer function.Closed loop feedback controlA system that uses a measurement of th
5、e output and compares it with the desired output.Closed loop transfer functionA ratio of the output signal to input signal for an interconnection of systems when all the feedback or feedforward loops have been closed or otherwise accounted for .Generally obtained by block diagram or signal flow grap
6、h reduction.Compensator An additional component or circuit that is inserted into the system to equalize or compensate for the performance deficiency.Components The parts,subsystems,or subassemblies that comprise a total system.Control systemAn interconnection of components forming a system configura
7、tion that will provide a desired response.Controllability matrixA linear system is controllable if and only if the controllable matrix Wc has full rank. For single input single output linear systems the system is controllable if and only if the determinant of the controllability matrix is nonzero.Co
8、ntrollable systemA system with unconstrained control input u that transfers any initial state x(0) to any other state x(t).Design The process of conceiving or inventing the forms, parts, and details of a system to achieve a reasoned purpose.DetectableA system in which the states that are unobservabl
9、e are naturally stable.Differential equationAn equation including differentials of a function.Digital control systemA control system using digital signals and digital computer to control a process.Discrete time approximation An approximation used to obtain the time response of a system based on the
10、division of the time into small increments delta t.Disturbance signalAn unwanted input signal that affects the systems output signal.Error signalThe difference between the desired output and actual output.Estimation The difference between the actual state and the estimated state.Feedback signalA mea
11、sure of the output of the system used as feedback tom control the system.Final valueThe value that output achieves after all the response have faded. Also referred to as the steady state.Frequency responseThe steady state response of a system to a sinusoidal input signal.Laplace transformA transform
12、ation of a function f(t) from the time domain into the complex frequency.Linear approximation An approximate model that results in linear relationship between the output and the input of the device.Linear quadratic regulatorAn optimal controller designed to minimize the quadratic performance index.L
13、inearized Made linear or placed in a linear form.LocusA path or trajectory that is traced out as a parameter is changed.Mathematical modelsDescriptions of the behavior of a system using mathematics.Matrix exponential functionAn important matrix function defined as eAt=I+At+(At)2+.that plays a role i
14、n in solution of linear constant coefficient differential equations.Minimum phase All the zeros of a transfer function lie in the left side of the s-plane.Negative feedbackThe output signal is fed back so that is subtracts from the input signal.Observability matrixA linear system is observable if an
15、d only if the observability matrix Wo has full rank.Observable systemA system with an output that possesses a component due to each state variable.ObserverA dynamic system used to estimate the state of another dynamic system given knowledge of the system input and measurements of system outputs.Open
16、 loop control systemA system that utilizes a device to control the process without using feedback.Optimal control systemA system whose parameters are adjusted so that the performance index reaches an extremum value.Optimization The adjustment of the parameters to achieve the most favorable or advant
17、ageous design.Output equationThe algebraic equation that relates state vector x, and the input u, to the outputs y, through the relationship y=Cx+Du.OvershotThe amount of the system output response proceeds beyond the desired response.Parameter designA method of selecting one or two parameters using
18、 the root locus method.Peak timeThe time for a system to respond to a step input and rise to a peak response.Performance indexA quantitative measure of the performance of a system.Physical variables The state variables representing the physical variables of the system.PID controller A widely used co
19、ntroller used in industry of the form G(s)=Kp+Ki/s+Kds.Pole placement A design methodology wherein the objective is to place the eigenvalues of the closed loop system in desired regions of the complex plane.Poles The roots of the denominator polynomial(i.e. The roots of the characteristic equation)
20、of the transfer function.Positive feedbackThe output signal is fed back so that it adds to the input signal.Reference inputThe input to a control system often representing the desired output.RobotA programmable computer integrated with a reprogrammable, multifunctional manipulator used for a variety
21、 of tasks.Robust controlA system that exhibits the desired performance in the presence of significant plant uncertainty.Robust stability criterion A test for robustness with respect to multiplicative perturbations in which stability is guaranteed if |M|1+1/G|.Root locus The locus or path of the root
22、s traced out on the s plane as a parameter is changed.Routh Hurwitz criterionA criterion for determining the stability of a system by examing the characteristic equation of the transfer function.Sampled data Data obtained for the system variables only at discrete intervals, data obtained once every
23、sampling period.Simulation A model of system used to investigate the behavior of a system by utilizing actual input signal.StabilityA performance measure of a system; a system is stable if all the poles of the transfer function have negative real parts.Stabilizable A system in which the states that
24、are not controllable are naturally stable.State differential equation The differential equation for the state vector: x=Ax+bu.State transition matrixphi (t), The matrix exponential function that describes the unforced response of the system.State variablesThe set of variables that describe the syste
25、m.State vectorThe vector matrix containing all n state variable; x1, x2, ., xn.State space representationA time domain model comprised of the state differential equation, x=Ax+Bu, y=Cx+Du.State variable feedbackWhen the control signal for the process is a direct function of all the state variables.S
26、teady state The value that after all the transient constituents of the response have faded. Also referred to as final state.SynthesisThe process by which new physical configurations of are created. The combining of separate elements or devices to form a coherent whole. System An interconnection of e
27、lements and devices for a desired purpose.Time delay A pure time delay, T so that events occurring at time t at one point in the system occurs at another point in the system at a later time (t+T).Time demain The mathematical domain that incorporates the time response and the description of a system
28、in terms of time t.Time varying control systemA system for which one or more parameters may varying with time.TradeoffThe need to make a judgment about how much compromise is made between conflicting criteria.Transfer function Under zero initial conditions, the ratio the Laplace transform of the out
29、put variables to the Laplace transform of the input variable.Transient responseThe constituent of the system response that disappears with time.Unit impulse A test input consisting of an impulse of infinite amplitude and zero width, and having an area of unity, used to determine the impulse response.Zero order holdA mathematical model of a sample and data hold operation whose input output transfer function is represented by G=(1-e-ts)/s.ZerosThe roots of numerator polynomial of the transfer function.
