This is really stupid

Control System TerminologyControl System Terminology

Input - Excitation applied to a control system from an external source .(REFERENCE)

Output - The response obtained from a system Feedback - The output of a system that is returned

to modify the input. Error - The difference between the input and the

output.

Thermostat

Temp Wanted

Air Temp

Heater Control

Types of Control SystemsTypes of Control SystemsOpen-Loop

– Simple control system which performs its function without concerns for initial conditions or external inputs.

– Must be closely monitored.Closed-Loop (feedback)

– Uses the output of the process to modify the process to produce the desired result.

– Continually adjusts the process.

Advantages of a Closed-Loop Advantages of a Closed-Loop Feedback System Feedback System

Increased Accuracy– Increased ability to reproduce output with varied

input. Reduced Sensitivity to Disturbance

– Self-correcting minimizes effects of system changes.

Smoothing and Filtering– System induced noise and distortion are reduced.

Increased Bandwidth– Produces sat. response to increased range of input

changes.

Major Types of Feedback Major Types of Feedback UsedUsed

Position Feedback– Used when the output is a linear distance or

angular measurement.Rate & Acceleration Feedback

– Feeds back rate of motion or rate of change of motion (acceleration)

– Motion smoothing– Uses a electrical/mechanical device called an

accelerometer

Building a Gun Fire Control System

Job Description: Train the gun turret to the proper firing position by moving a joy stick left or right depending on the direction needed. This must be performed as fast as possible.

Safety Consideration:For your protection,you will be located insidea windowless protectiveenclosure inside the gunturret.

MIDN Pineda

Time

Old Position

NewPosition

Turret Position with Feedback

DampingDamping

Old Position

New Position

Underdamped

OverDamped

Critically Damped

Realistically Damped

Tracking Systems??Tracking Systems??

Determines location or direction of a target on a near-continuous basis.

Ideal system would maintain contact and constantly update the target’s bearing (azimuth), range and elevation.

WHAT IS A TARGET?…

This is not a TargetThis is not a Target

Automatic Tracking Systems Automatic Tracking Systems (Related to Feedback)(Related to Feedback)

Target Tracking Parameters Line-of-Sight(LOS) Tracking Line

Target Tracking ParametersTarget Tracking Parameters

AzimuthElevationRangeRelative Target Velocity

– Target’s motion with respect to the platform’s motion

Tracking TermsTracking Terms

TrackingElement

Line-of-Sight

Tracking Line

Error

Angle-Tracking Servo Angle-Tracking Servo SystemsSystems

Five Basic FunctionsSense position error magnitude and

directionProvide position feedbackProvide data smoothing / stabilizationProvide velocity feedbackProvide a power-driving device

RELATE TO FEEDBACK CONTROL SYSTEMS

Uses of Angle-Tracking Servo Uses of Angle-Tracking Servo SystemsSystems

Monotrack fire control radarsHoming missilesAcoustic homing torpedoesAviation fire control tracking systems

Methods of trackingMethods of tracking

Sequential Lobing Conical scanConical scan on receive only (COSRO)Monopulse

Basic Principle: Target energy return is strongest on the axis of the beam, diminishes further from the axis.

axisMethods of Tracking: * Sequential Lobing * Conical Scan * COSRO * Monopulse

Position Error Magnitude & Position Error Magnitude & DirectionDirection

Sequential LobingSequential LobingL L LR R R

Antenna looking left of target

Antenna Pointing directly at target

Antenna looking right of target

Return Signals form Two Beams

* Simplest Method

* Multiple Beams * Compare Returns

* Relatively Slow

* Still used by some countries

Conical ScanningConical Scanning

* Rotates a beam in a circle producing a cone of energy.

*Rotate the feed horn in a small circle around the axis of the fixed parabolic antenna.Antenna

Lobe Of Energy Pattern of scanning

Determining Tracking Error Determining Tracking Error Using Conical ScanUsing Conical Scan

Locus of Beam Centers

Beam

Time

PulseReturnAmplitude

Equal AmplitudeSensor Return Signal

Antenna Axis

Target Position is in the Center of the Conical Scan (On Antenna Axis)

Determining Tracking Error Determining Tracking Error Using Conical ScanUsing Conical Scan

Locus of Beam Centers

Beam

Time

PulseReturnAmplitude

Varying AmplitudeSensor Return Signal

Antenna Axis

Target Position Off the Center of the Antenna Axis

Example: AN/SPG-53AExample: AN/SPG-53A

COSROCOSROConical Scan on Receive OnlyConical Scan on Receive Only

* Transmits pulses on axis of the antenna.* Measured strength of return around the axis of the antenna.* Positions the antenna based on the return. DECEPTIVE: Looks like non-Scanning pulse radar Antenna

MonopulseMonopulse Developed to overcome tracking errors involved with

conical scanning and sequential lobing. Two or more beams are transmitted simultaneously

and an amplitude comparison is mode between the returns. – One reflector but uses two or more feed horns.– Each simultaneous beam can be identified by tagging it with

some type of information such as slight polarization.– Usually 4 beams: 2 for elevation and 2 for azimuth

Very complex and expensive.

Providing a Stable Tracking Providing a Stable Tracking SystemSystem

All tracking systems require some stabilization. Three classes of stabilization for Tracking

Systems– Unstabilized - Not stabilized in any axis– Partially Stabilized - Subsystem is stabilized on one

axis.– Fully Stabilized - Completely free of any rotational

disturbances. Gyroscopes provide the stable reference.

Basic Gyroscope PrinciplesBasic Gyroscope Principles The gyro spins at a very high velocity, and

its spin axis remains aligned with terrestrial meridians.

Inertia– Rigidity (A gyro will remain at a fixed

orientation in space if no force is applied to it)– A gimbaled gyro makes a good reference to

cancel out platform role, pitch and yaw. (On a ship!)

Basic Gyroscope PrinciplesBasic Gyroscope Principles

Precession– A gyro’s spin axis has a tendency to turn at right angles

to the direction of the force applied to it.– Used to convert torque required to move the gyro is

converted into a means of controlling system gain. The gyro has three axes:

– spin axis– torque axis– precession axis

Gyroscope TheoryGyroscope Theory

Accelerometers!!!

Now, put ‘em together!!!!Now, put ‘em together!!!!

Range Tracking Angle Tracking

One dead duck…………………..One dead duck…………………..

Questions?Questions?

QuizQuiz

Question 1Question 1

What does COSRO stand for?

Question 2Question 2

Damping is:A. A type of horizontal polarization.B. The process by which your weapon

system/tracking system turns to a new contact without overshooting the target.

C. Transmission from a Phased Array Radar.D. Getting really wet.

Question 3Question 3

Give an example of an Open Loop Control System.

Not a stovetop burner

Question 4Question 4

Give an example of an Closed Loop Control System.

Question 5Question 5

In order to stabilize your weapons launcher or tracking system, the system must be able to receive input from what piece of equipment?

A. BSY-1B. The CaptainC. The GyroscopeD. The SPY-1D

Extra CreditExtra Credit

How many Nuclear Powered ships does the Navy currently own and operate?