SENSORS & CONTROL ENES 100 Bruce Jacob SLIDE 1
Sensing, Actuation, Control ENES 100 Prof. Bruce Jacob Electrical & Computer Engineering (with enormou...
Feedback: Wheel rotation speed Are any wheels slipping? Are any wheels rotating much more slowly than the others? If so, slipping brakes are pulsed to try to recover traction.
SENSORS & CONTROL ENES 100 Bruce Jacob
Power-Assist Steering OPEN LOOP
SLIDE 17
Input to System
Torque on Steering Wheel
Controller
Plant
Software/Hardware
Thing being Controlled
Magnify Force (gain is variable, rel. to veh. speed)
Vehicle Speed
Hydraulic Steering System
System Output
Car Turns
SENSORS & CONTROL ENES 100 Bruce Jacob
Compass-Assisted Steering CLOSED LOOP
SLIDE 18
Input to System
Controller
Plant
Software/Hardware
Thing being Controlled
System Output
Feedback
Compass Direction (desired)
Appropriate Degree of Turning
Steering System
Vehicle Turns
Feedback: Current vehicle direction of travel If direction of vehicle is not equal to the desired compass point, control system adjusts steering appropriately (note: vehicle can point one way and go another)
SENSORS & CONTROL ENES 100 Bruce Jacob
Manual Throttle OPEN LOOP
SLIDE 19
Input to System
Controller
Plant
Software/Hardware
Thing being Controlled
Set Throttle
System
Open or Close Valve
Engine Fuel Line
Output
Engine Speeds Up (Slows Down)
SENSORS & CONTROL ENES 100 Bruce Jacob
Governor-Controlled Throttle CLOSED LOOP
SLIDE 20
Input to System
System
Controller
Plant
Software/Hardware
Thing being Controlled
Output
Feedback
Set Throttle
Open or Close Valve
Engine Fuel Line
Engine Speeds Up (Slows Down)
Feedback: Engine shaft rotation speed If load on engine increases, the rotation slows, causing the governor to open the throttle
SENSORS & CONTROL ENES 100 Bruce Jacob
Hovercraft A OPEN LOOP
SLIDE 21
Input to System
Controller
Plant
Software/Hardware
Thing being Controlled
Countdown Timer
Turn Right
Steering Mechanism
System Output
Hovercraft Turns
SENSORS & CONTROL ENES 100 Bruce Jacob
Hovercraft B CLOSED LOOP
SLIDE 22
Input to System
Controller
Plant
Software/Hardware
Thing being Controlled
System Output
Feedback
Light Sensors
Control Algorithm
Steering Mechanism
Hovercraft Turns
Feedback: Orientation changes → course changes As hovercraft changes orientation with respect to tape, light sensor readings change, causing course corrections
SENSORS & CONTROL ENES 100 Bruce Jacob SLIDE 23
PID Controller Proportional, Integral, Derivative Input to System
e(t)
u(t)
Controller Software/Hardware
Plant
System Output
Thing being Controlled
Feedback
t
de u ( t ) = K P e ( t ) + K I ∫ e ( t ) dt + K D ------dt 0 •
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Proportional term ensures the system reacts as soon as there is a change in the system: change in new output follows the error. Integral term provides hysteresis, tracks effectiveness of control system: measures delta between output and input to date. Derivative term anticipates future behavior: reacts to quick changes in plant output vs. input.
SENSORS & CONTROL ENES 100 Bruce Jacob SLIDE 24
Example System Thermostat — A Popular Controls Example
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Water heater: controlled by voltage
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Sensor: temperature (V representing T)
SENSORS & CONTROL ENES 100 Bruce Jacob SLIDE 25
Example System Thermostat — A Popular Controls Example
