Page 1 : 9.13. INDUSTRIAL CONTROLLERS, error detector. Thus error detected is used as an actuating signal for control action through a, TYPES OF INDUSTRIAL CONTROLLER., 9.35, CONTROL SYSTEMS, An automatic control system is used to maintain its output within desirable limit by mean, ta control action. Any deviation of the output from the reference input is detected by an, controller., 1. Proportional Control, In proportional control, actuating signal for the control action in a control system is proportional to the, error signal. It is desirable that the control system be underdamped for the point of view of quick, response. The sluggish overdamped response of a control system can be made faster by increasing, forward path gain of the system., R(s), E(s), P(s), K., s(s + 250,), Cs), Here output of the controller and error are related by, P(s) = Kp E(s) or P(t) = Kp E(t), %3D, %3D, Effects of Proportional Controller., increased by K,, (i) on, vJ Transent Response woTsence ie., stability deireares, vi) Propotional Controller is esetally, an' amplisfier with adjiestable gain., (ü) į decreased by k,, =) S' = I, %3D, (üii) Mp increases, (iv) Steady state error reduces, 2. Derivative Control, For derivative control action, actuating signal consists of proportional error signal added with derivative, of the error signal., P(s) = KpS. E(s), de(t), P(t) = Kp, or,, dt, E(s), P(s), K,S, s(s+ 250,), Effects of Derivative Controllers., pollovtco, Not usedin idolabon., (1) Type and order of the system reduces by 1, (ü) Oscillation has died out hence transient response improves. V)steady stati emor increases, 3 Integral Control, For integral control action, actuating signal consists of proportional error signal., S, P(s), E(s), !3!, E(s), P(s), s(s+250), P(s) =, E(s), P(s) = k;f e(t)dt, 1, 介

Page 2 : CONTROL SYSTEMS, 9.36, Effects of Integral control:, (i) Increses type and order by "1", (i) Steady state error reduces, (i)Make system less stable, (iv) Improves the steady state response, For Integral control action :, as e . lialob, With integral control, Without integral control, 25, S.N., Input, 1., Unit ramp, @n, 25, 2., Unit parabolic, Effect of Control methods on Time response, S.N., Type of Control action, %Mp, Proportional control, not affected not affected increases, decreases, 1., not affected, Derivative control, decreases, decreases, not affected, not affected not affected not affected decreases, 2., increases, decreases, 3., Integral control, not affected, 4., Derivative feedback, increases, increases, increases, decreases, increases, control, COMPOSITE CONTROLLER MODES., 1. P.I. Controller (Memory Based), abe ele, P(s), E(s) = Kp +, K,, S, K,, P(s) = | K, +, E(s), P(t) = Kpe(t) + K; e(t)d(t), R(s), E(s), P(s), s(s + 250.), C(s), K,, Effects of P.I. Controller:, श, (1) Improve only steady state characteristics, ViI) Improves Gm. Pinm,, S Vi) Reducus Maximum overshoot., in Fitra out high frequenty mose -, (ü) Improve type and order of system by one, (iii) Increases rise time, (iv) Reduces stability, (v) Bandwidth reduces, (vi) Increases error constant, 2. P.D. Controller, P(s), Kp + Kps, E(s), %3D, P(s) = (Kp + Kps) C(s), de(t), P(t) = K, e(t) + Kp, dt

Page 3 : CONTROL SYSTEMS, 9.37, R(s), E(s), P(s), s(s+ 25m,), C(s), Effects of P.D. Controller :, (1) Improve damping ratio, (ü) Improve transient response only, (ii) Reduce maximum pead over shoot, v rerea, (iw) Increaes bandwidth, (v) Improve gain margin; phase margin and resonant peak mr., (vi) Does not effect on Itype and order of system, (vüi) Increases stability, 3. P.I.D. Controller, P(s), E(s) = Kp + Kps +, K,, S, P(S) = (Kp + Kps) E(s), P(t) = Kp e(t) + Kpdet) +K,S e(t)dt, dt, KOS, R(s), E(s), P(s), on?, C(s), Kp, s(s+2ğw. ), K,, Effects of PLD. Controller :, ala se, (i) Improves both transient and steady state response, (i) Reduces rise time, (ii) Increases stability, (iv) Increases bandwidth, (v) Increases type and order of system by "1", (vi) Eliminate stead state error between input & output, beisl