Software Engineering/Mechatronics 3DX4 Slides 1: Introductionleduc/slides3dx3/3dx3slides1.pdf · 2014. 1. 8. · Software Engineering/Mechatronics 3DX4 Slides 1: Introduction Dr.

Software Engineering/Mechatronics 3DX4

Slides 1: Introduction

Dr. Ryan Leduc

Department of Computing and Software

McMaster University

Material based on lecture notes by P. Taylor and M. Lawford, and Control Systems Engineering by N. Nise.

c©2006-2012 R.J. Leduc 1

Overview

◮ What is a control system?

◮ Example control systems

◮ Terminology , Response characteristics, & Systemconfigurations

◮ Analysis and Design Objectives

◮ The Control Systems Design Process

◮ Case Study: Antenna Azimuth Control

c©2006-2012 R.J. Leduc 2

What is a Control System?

◮ In its simplest form a control system provides an output(response) for a given input (stimulus)

Figure 1.1: Simplified description of a control system

c©2006-2012 R.J. Leduc 3

Why do We Need Control Systems?

◮ Power amplification (e.g. power steering)

◮ Remote control (e.g. Telerobotic surgery, bomb disposalrobot, etc.)

◮ Convenience of input (e.g. Convert thermostat slider positionto room temperature)

◮ Compensation for disturbances

◮ Improve system speed, accuracy, repeatability, performance,etc., etc.

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Example Control Systems I

Figure 1.3

Rover was built to work incontaminated areas at ThreeMile Island in Middleton, PA,where a nuclear accidentoccurred in 1979. The remotecontrolled robots long arm canbe seen at the front of thevehicle.

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Example Control Systems II

Figure 1.4

(a) Video laser disc player.

(b) Objective lens reading pitson a laser disc.

(c) Optical path for playbackshowing tracking mirrorrotated by a controlsystem to keep the laserbeam positioned on thepits.

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Example Control Systems III

Figure 1.7

Computer hard disk drive,showing disks and read/writehead.

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System Configurations

Figure 1.6

Block diagrams ofcontrol systems:

(a) Open-loop system.

(b) Closed-loopsystem.

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Transient and Steady State Response

Figure 1.5: Elevator input and output

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Transient Response Tradeoffs

Figure 1.10

Response of a positioncontrol system showingeffect of high and lowcontroller gain on theoutput response.

Percent overshoot =a

b× 100%

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Stability

Total response = Natural response + Forced Response

◮ Natural Response (aka homogeneous solution): Evolution ofsystem due to initial conditions.

◮ Forced Response (aka particular solution): Evolution ofsystem due to input.

◮ Generally a system is stable if the natural response eventuallygoes to zero or at worst oscillates with some fixed amplitude.

◮ In an unstable system the natural response grows withoutbound, swamping the forced response and system is no longercontrolled.

ie a bounded input does not create a bounded output.

◮ In general, a control system must be stable to be useful.

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Control Objectives

1. Stabilize the system.

2. Produce the desired transient response.

3. Decrease/eliminate steady state error.

4. Make system robust to withstand disturbances and variationsin parameters.

5. Achieve optimal performance.

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Case study: Antenna Azimuth Position Control

Figure 1.8

The search for extraterrestriallife is being carried out withradio antennas like the onepictured here. A radio antennais an example of a system withposition controls.

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Azimuth Position Control System for Antenna

Figure 1.9

(a) Systemconcept

(b) Detailedlayout

(c) Schematic

(d) Functionalblock diagram

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How do You Design a Control System?

Figure 1.11: The control system design process

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Test Waveforms

◮ Test signals used toverify design.

◮ Table 1.1 shows thestandard test signalsused.

Table 1.1: Test waveforms used in control systemsc©2006-2012 R.J. Leduc 16