Presentation on theme: "This is really stupid. Control System Terminology S Input - Excitation applied to a control system from an external source.(REFERENCE) S Output - The."— Presentation transcript:
Control System Terminology S Input - Excitation applied to a control system from an external source.(REFERENCE) S Output - The response obtained from a system S Feedback - The output of a system that is returned to modify the input. S Error - The difference between the input and the output.
Negative Feedback Control System CONTROLLER CONTROLLED DEVICE FEEDBACK ELEMENT ++ + -
Types of Control Systems ø Open-Loop –Simple control system which performs its function without concerns for initial conditions or external inputs. –Must be closely monitored. ø 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 Feedback System ø Increased Accuracy –Increased ability to reproduce output with varied input. ø Reduced Sensitivity to Disturbance –Self-correcting minimizes effects of system changes. ø Smoothing and Filtering –System induced noise and distortion are reduced. ø Increased Bandwidth –Produces sat. response to increased range of input changes.
Major Types of Feedback Used ø Position Feedback –Used when the output is a linear distance or angular measurement. ø 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
Tracking Systems?? l Determines location or direction of a target on a near-continuous basis. l Ideal system would maintain contact and constantly update the targets bearing (azimuth), range and elevation. l WHAT IS A TARGET?…
Automatic Tracking Systems (Related to Feedback) ø Target Tracking Parameters ø Line-of-Sight(LOS) ø Tracking Line
Target Tracking Parameters ø Azimuth ø Elevation ø Range ø Relative Target Velocity –Targets motion with respect to the platforms motion
Tracking Terms Tracking Element Line-of-Sight Tracking Line Error
Angle-Tracking Servo Systems ø Five Basic Functions øSense position error magnitude and direction øProvide position feedback øProvide data smoothing / stabilization øProvide velocity feedback øProvide a power-driving device
Uses of Angle-Tracking Servo Systems ø Monotrack fire control radars ø Homing missiles ø Acoustic homing torpedoes ø Aviation fire control tracking systems
Methods of tracking ø Sequential Lobing ø Conical scan ø Conical scan on receive only (COSRO) ø Monopulse
Basic Principle: Target energy return is strongest on the axis of the beam, diminishes further from the axis. axis Methods of Tracking: * Sequential Lobing * Conical Scan * COSRO * Monopulse Position Error Magnitude & Direction
Sequential Lobing L L L R 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 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 Using Conical Scan Locus of Beam Centers Beam Time Pulse Return Amplitude Equal Amplitude Sensor Return Signal Antenna Axis Target Position is in the Center of the Conical Scan (On Antenna Axis)
Determining Tracking Error Using Conical Scan Locus of Beam Centers Beam Time Pulse Return Amplitude Varying Amplitude Sensor Return Signal Antenna Axis Target Position Off the Center of the Antenna Axis
COSRO Conical 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
Monopulse ø Developed to overcome tracking errors involved with conical scanning and sequential lobing. ø 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 ø Very complex and expensive.
Providing a Stable Tracking System ø All tracking systems require some stabilization. ø 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. ø Gyroscopes provide the stable reference.
Basic Gyroscope Principles l The gyro spins at a very high velocity, and its spin axis remains aligned with terrestrial meridians. l 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 Principles l Precession –A gyros 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. l The gyro has three axes: –spin axis –torque axis –precession axis
Now, put em together!!!! l Range Tracking l Angle Tracking One dead duck…………………..
Automatic Range Tracking Uses range gate method of determining range error. The range gate pulse is centered on the expected range. Actual Return Expected Return Centered on Predicted Range. Summation of actual pulse energy that falls within the boundaries of the expected pulse. (Second half energy amount is inverted so easier to compare). AB Range
Question 2 l 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 3 l Give an example of an Open Loop Control System. Not a stovetop burner
Question 4 l Give an example of an Closed Loop Control System.
Question 5 l 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-1 B.The Captain C.The Gyroscope D.The SPY-1D
Extra Credit How many Nuclear Powered ships does the Navy currently own and operate?