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ENT364/4 – Control System Sazali Yaacob BEng(Malaya), MSc(Surrey), PhD(Sheffield) Chartered Engineer, CEng (United Kingdom) Member Institute of Engineers and Technologist, MIET (United Kingdom) s.yaacob@unimap.edu.my 019-4772260
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Course Assessment Lecture 3 hours per week Lab/Tutorial/Design2 hours per week Final Examination 50 marks Mid-SemesterTest10 marks Quiz/Design25 marks Lab works15 marks
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Weekly Schedule Week 1: Introduction Week 2: Modeling Week 3: Modeling Week 4: Time Response Week 5: Time Response Week 6: Time Response/Root Locus Week 7: Root Locus/Mid-Semester Revision
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Weekly Schedule Week 8: Frequency Response Week 9: Frequency Response Week 10: Frequency Response Week 11: Frequency Response Week 12: Design Week 13: Design Week 14: Revision
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OBJECTIVES Basic terminologies. Open-loop and closed-loop Block diagrams Control structure Advantages and Disadvantages of closed-loop Introduction to control system
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Human control
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System control
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GPS Control
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Force Control
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Vision Control
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Primary Source (Loudspeaker) Secondary source (Actuator) Block Diagram for Active Noise Cancellation 24 cm Error Microphone Sensor Microphone 36 cm Primary pathError path 12 cm BEFORE ANCAFTER ANC Sound Control
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Satellite Control
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Magnetometer Magnetorquer Driver OBCACS Torque command for the MT Processed attitude data Attitude Ref
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Process Control
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Pilot Plant
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Servo Control
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Steering Control Complete System Set-up for Mobile Robot using Mecannum wheel
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Omni-directional Motion for the Mobile Robot
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Basics terminologies Sub-system and System subsystem subsystem subsystem –System is a combination of physical and non-physical components that are configured to serve certain tasks to maintain the output –Subsystem is part of the system that is grouped for a certain function blower room thermostat
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Plant subsystem input output Plant is the main subsystem where the control signal will act on and produce the output. plant
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Disturbance is unwanted signal that may sway the output Controller is a subsystem that is used to ensure the output signal follows the input signal controller plant input disturbance output + Disturance and Controller
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Error controller plant - + + + input Error is a signal made up of the difference of input and output error disturbance
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Control Structure For any control system the following flow structure is needed model analysis design Objective
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Example of an open-loop system motor Turn table rheostat amplifier motor Turn- table Required speedActual speed Open-loop system
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Closed-loop system example of closed-up system motor tachometer + - Turn-table rheostat Differential amplifier amplifier motor Turn- table tachometer required speed Actual speed + -
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Block Diagram Transfer function, H input, Routput, Y Transfer function is the ratio of the ouput over the input variables The output signal can then be sderived as Example of multi-variables ++ + - R C E B Block diagram reduction H G H.G = abcac
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Feed Forward and Feedback Transfer function + - R(s)R(s) E(s)Y(s)Y(s) B(s)B(s) E(s error signal B(s) feedback signal R(s) reference signal Y(s) output signal Feed forward transfer function Feedback transfer function
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Open Loop Transfer Function H(s) G(s)G(s) H(s)G(s)H(s)G(s) E(s)E(s)Y(s)Y(s) B(s)B(s) E(s)E(s)B(s)B(s) Open loop transfer function + - R(s)R(s) E(s)Y(s)Y(s) B(s)B(s)
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Closed Loop Transfer Function The feedback is. Variable difference Characteristic equation Closed-loop transfer function The error signal is The closed loop transfer function is The characteristic equation is very important in determining the behaviour of a system
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Model Many type of models: Physical model Graphical model Mathematical model Example: Current-voltage relationship v – voltage in V i – current in A R – resistance in Ohm Example: Force-deflection realtionship f – force in N k – spring constant x – displacement in m Mass-spring model sistem jisim-pegas
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From Newton’s law where m is the mass and a is the acceleration. Substituting Example: Mass-spring model - applied force x - displacement - reaction force Velocity Acceleration
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Black-box Modelling
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Input-output reltionship Torque-Speed Characteristics of a Squirrel-Cage Induction Motor
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Identification Procedure
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Neural Network Training Forward Plant Modeling
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Neural Network Structure A two layer Artificial Neural Network
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Neural Network Control The Experimental Work
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Input-output Data
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Analysis Transient state A state whereby the system response after a pertubation before the response approach to a steady condition Steady state A state whereby the system response becomes steady after a transient state Stability The condition of the steady state. If the response converges to a finite value then it is said to be in a stable condition and if the response diverges, it is known to be unstable.
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Time Response Transient s stateSteady state
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Example of Time Response
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Design Analogue controller A controller that used analogue subsystem Digital Controller A controller that used computer as its subsystem computerdriveplant sensor _ + referene input Actual output
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Adaptive Control
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Computer Control The Control Experiment.
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Step Input The Induction Motor Unit Step Speed Response with the Direct Inverse Control Scheme
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Sinusoidal Input Speed Response to a Sine Wave Reference Signal under DIC Scheme.
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Ramp Input Speed Response to a Ramp Wave Reference Signal under DIC Scheme.
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Square-wave Input Speed Response to a Square Wave Reference Signal under DIC Scheme.
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Advantage of Feedback Loop (1) Not susceptible to disturbance H + + + - d r y Assume, then changes in y is negligible Not sensitive to parameters changed
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(2) Insensitive to changes in parameters Consider H y+ - r Define sensitvity as where T is the transfer function of the system is the parameter of the system. Closed-loop transfer function Let us investigate the effect on the system when the plant is subjected to perturbance i.e.,. If, thus.
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(3) Increased in bandwidth Consider a first order where K is the dc gain and T is the time constant If a feedback is applied a + - The closed-loop transfer function is Hence the new time constant is reduced and increased the system bandwidth
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Output for open loop Output for feedback system. If thus. (4) Accurate control. + - R(s)R(s)Y(s)Y(s) This means that the output will follow the input which signify a god control objective
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