pengenalan sistem kontrol

Dede Iskandar, ST

Pengenalan Sistem Kontrol Topik Bahasan

Konsep Dasar Sistem KontrolJenis Sistem KontrolContoh-contohDesain Sistem Kontrol

Konsep Dasar Sistem Kontrol Sistem = Kombinasi komponen2 yang

bekerja bersama2 untuk mencapai tujuan tertentu (fisik atau abstrak,biologi,ekomoni)

Sistem Kontrol = sistem yang dapat di-identifikasi atau ditengarai terdiri dari minimal 2 (dua) bagian utama, yaitu:- Plant/proses, obyek yang dikendalikan- Kontroller/Pengendali, yang mengendalikan

Jenis Sistem Kontrol

Secara garis besar Sistem Kontrol Loop terbuka Sistem Kontrol Loop tertutup

Sistem Kontrol Loop Terbuka Sistem yang kelurannya tidak mempunyai

pengaruh terhadap aksi kendali Keluaran sistem tidak dapat digunakan

sebagai perbandingan umpan balik dengan masukan.

ProsesKontrollerMasukan Keluaran

Sistem Kontrol Loop TerbukaKarakteristik Sistem kendali lup terbuka : output tidak diukur maupun di

umpanbalikkan bergantung pada kalibrasi hubungan antara output dan input

diketahui tidak ada ‘internal disturbance’ maupun

‘eksternal disturbance’ terkait dengan waktu

Sistem Kontrol Loop TerbukaKelebihan: konstruksinya sederhana dan

perawatannya mudah lebih murah tidak ada persoalan kestabilan cocok untuk keluaran yang sukar diukur

/tidak ekonomis (contoh: untuk mengukur kualitas keluaran pemanggang roti)

Sistem Kontrol Loop TerbukaKelemahan: gangguan dan perubahan kalibrasi untuk menjaga kualitas yang diinginkan

perlu kalibrasi ulang dari waktu ke waktuContoh : - kendali traffic (lalu lintas)- mesin cuci

Sistem Kontrol Loop tertutup- Sistem yang memiliki umpan balik untuk

mengurangi kesalahan atau beda antara masukan acuan dengan keluaran

Sistem Kontrol Loop tertutup

reference input signal,

comman

d

isyarat masukan

acuan, perintah, set-point

feedback signal

isyarat umpan-balik

output signal

luaran, isyarat luaran, hasil, produk

PROSES(PLANT)

control signal

isyarat kendali

PENGENDALI(CONTROLLE

R)

Contoh-Contoh Sistek Kontrol Open Loop

Pemanggang Roti Motor DC

Contoh-Contoh Sistem Kontrol Sistem Kontrol Kecepatan – James Watt

Plant : engineControlled Variable : Engine speedControl Signal : jumlah Fuel

Contoh-Contoh Sistem Kontrol Kontrol Manipulator Robot

Contoh-Contoh Sistem Kontrol Sistem Kontrol Temperatur

Contoh-Contoh Sistem Kontrol

Kontrol Elevator Pesawat

Contoh-Contoh Sistem Kontrol Sistem Kontrol Level

Contoh-Contoh Sistem Kontrol SK Radar Tracking Pesawat

Radar mendeteksi posisi & kec pesawat

Contoh-Contoh Sistem Kontrol Radar mendeteksi posisi & kec pesawat Dipakai komp u menentukan lead &

firing angle penembak Sudut2 ini diumpankan ke power amp

sebagai driver motor Feedback signal menjamin alignment

penembak sesuai yang diset komputer

Contoh-Contoh Sistem Kontrol SK Autopilot Kapal Laut

Gyro-Compas u ngitung actual headingAutopilot hit demand rudder anglesteering

geerRudder menyebabkan hull(lambung kapal)

bergeser

Contoh-Contoh Sistem Kontrol SK Autopilot Kapal Laut

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Road conditions

Speed

Steering

Noise

desired direction

actual direction

Response direction of travel

Time

Response speed

Time

Desired speed

Actual speed

Contoh-Contoh Sistem Kontrol Steering Automobile

Actual output

AutomobileSteering

mechanismDriver

Desired speed or direction

Process/

Plant

ActuatorController

Desired output

Actual output

Disturbance

Open-loop menggunakan actuating device untuk mengontrol process secara langsung tanpa feedback

Kerugian : sensitivity to disturbances and system’s inability to correct for these disturbances

Steering Automobile :Open loop

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Actual output

AutomobileSteering

mechanismDriver

Measurement

Comparison

Desired speed or direction

Process/

Plant

ActuatorController

Sensor

Desired output

Actual outputerror+

-

feedbackMeasurement output

Disturbance

SK Steering Automobile : Close loop

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Contoh-Contoh Sistem Kontrol Mesin Tenun

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feed-eye and resin bath

Filament winding process

Mandrel

Contoh 2: Komputer Kontrol untuk Mesin Tenun

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Master

Computer

Sub CPU

1

2

3

4

PWM 1

PWM 2

PWM 3

PWM 4

Motor 1

Motor 2

Motor 3

Motor 4

Motion 1

Motion 2

Motion 3

Motion 4

Contoh 2: Komputer Kontrol untuk Mesin Tenun

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2nd Motion control

DC/AC/stepping motor

PWM Unit

Optical

Encoder

Desired position of motion 2

Actual position

error+

-

Feedback: position signal

Speed feedback

Disturbance

Sub CPU #2

Tachogenerator

Contoh 2: Komputer Kontrol untuk Mesin Tenun

Desain Sistem Kontrol

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Performance specifications: It is very important to define, in numerical terms, what

is the expected performance of the control system One possibility is to examine the behavior of the output

in response to a sudden change in input: known as the “step response”

Steady state error

overshoot

Rise time

Time (s)

Out

put

Typical requirements:

• No overshoot• Zero steady state error• Rising time as small as possible

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Control System Design(1) Understand the system to be controlled. Define the objectives of the

controller (establish control goals)

(2) Identify the variables to control, build a simple mathematical model of the system and examine the system behavior. Does the model captures essential features of the system? If not revise the model.

(3) Write the specifications for the variables

(4) System configuration: sensor, controller, actuator, etc.

(5) Developing a model of the process, the actuator, and the sensor

(6) Describe a controller, select key parameters to be adjusted.

(7) Analyze and simulate the controller. Are objectives achieved? If not, change the control strategy and redesign

(8) Test the controller on the real system. Can the control law be “fine tuned” to achieve desired behavior? If not iterate until a satisfactory solution is obtained

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Step 1: Understand the system to be controlled. Define the objectives of the controller (establish control goals)

For example :

control goal: to control the velocity of motor accurately

or to control the direction of the motor

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Step 2: Identify the variables to control, build a simple mathematical model of the system and examine the system behavior.

control variable: angular of steering wheel

mathematical model: f(v, t, P)

control variable: position of each motion

mathematical model: f(x, y, z, , v, t)

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Step 3: Write the specifications

e.g. range of control variable values accuracy of control rise time of system response percent overshoot the response settling time peak time …...

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Step 4: System configuration: choosing control system components, which are assembled into a viable system, based upon requirements.

Sensor: tachogenerator, optical encoder, etc.

Actuator: AC/DC servo motor with reduction gear boxes

Controller: PWM unit; microcomputer for position control of each motion; PC used as master

computer, to

control the coupling movement of several motions

Control algorithm: PID controller

Computer programming language: C++ and Assembler

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DC motor

tachometer

Optical encoder

http://www.micromo.com/

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Step 5: Developing a model of the process, the actuator and the sensor.

model of the winding process

AC/DC servo motor model

Encoder and other sensor models

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Step 6: Decide on a control strategy, select key parameters to be adjusted.

In example 1:

possible control law: P controller

Throttle=K*(desired speed - actual speed)

In example 2:

possible control law: PID controller

T

IDP edtKeKeKV0

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Step 7: Analyze and simulate the controller, and select

key parameters to be adjusted

System characteristics to be analyzed include: transient response steady-state error stability sensitivity: system behavior changes with changes in component

values or system parameters, e.g. temperature, pressure, etc. (systems must be built so that expected changes do not degrade performance beyond specified bounds)

evaluation of time response of the system for a given input

Parameters to be adjusted: KP, KD, KI

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Step 8: Test the controller on the real system.

Interference (Electromagnetic, noise, etc.)Hardware and softwareController parameters…...

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Step 1: Establish control goals

Step 2: Identify the variables to control

Step 3: Write the specifications for the variables

Step 4: System configuration: sensor, controller, actuator, etc.

Step 5: developing models for process, actuator, sensors

Step 6: Describe a controller, select key parameters

Review: Steps of control system design

Step 7: Analyze and simulate the controller

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Specification: control goals, variables, etc.

Modeling and System Behavior

Controller design, PID; Root Locus analysis

Feedback systems

Time domain specifications & system stability

Frequency domain

Bode plot

Compensator design

Aspects of industrial PID State variable

Autotuning rules of PID Analysis & design

Materi Sistem Kontrol Dasar

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Review questions:(1) Give examples of open-loop systems(2) Name several applications for feedback control system(3) Name reasons for using feedback control systems and reasons

for not using them(4) Functionally, how do closed-loop systems differ from open-loop

systems?(5) Name two possible control law for motion controls(6) Name advantages of having a computer in the control loop(7) Three major design criteria. (1) transient response, (2)steady-

state error and (3) stability. Briefly describe the criteria.(8) Name components in a control system(9) Briefly describe performance specifications of control systems(10) Describe steps of a control system design.

Referensi

Sistem Kontrol Otomasti, K Ogata Automatic Control System, Benjamin C

Kuo Advance Control Engineering, Ronald

SB Internet dll