Open/Closed Loop Systems 1/8● INPUT: ● You run the mile every afternoon

● You record time with stopwatch● OUTPUT:● Stopwatch times each mile

● PROBLEM: Your times do not improve

● INPUT: You run a mile on trackCoach times your runCoach gives you ● FEEDBACK (tips)

● OUTPUT: Your mile time improves

FEEDBACK

Open Loop System:

OUTPUTINPUTON / OFF

● One-way connection between INPUT and OUTPUT

2/8

ON / OFF

OUTPUT

INPUT

Water ON / Water OFF

Open Loop System:● One-way connection between INPUT and OUTPUT

3/8

●NO direct connection between OUTPUT and INPUT

INPUT: ON/OFF OUTPUT: ON/OFF

EXAMPLE: light + switch

●Open Loop System: A control system with no automatic FEEDBACK loop

INPUT: set light,

medium, dark

FEEDBACK: setting reached – toast pops up

light

OUTPUT: toast is way you want it

medium

dark

●A control system with an automatic feedback loop●A direct connection between output and input

Closed Loop System:

EXAMPLE: a toaster w/light – medium – dark settings

●Closed Loop System: A control system with an automatic FEEDBACK loop

4/8

●A control system with an automatic feedback loop● A direct connection between OUTPUT and INPUT

140○

watertemperature

control

temperature sensor/control

“Heat water to 140 degrees”

“At 140: Stop heating.”

“Under 140: Start heating.”+ -

feedbackWaterheater

Closed Loop System: 5/8

Closed Loop System: 6/8

● A direct connection between OUTPUT and INPUT

Thief :near homeat night

●Closed Loop System: A control system with an automatic FEEDBACK loop

EXAMPLE: outdoor lights w/motion detector

Electric eye detectsinfrared

INPUT (infrared waves)

Spotlights turn ON.OUTPUT

FEEDBACK

Closed Loop System: 7/8

INPUT

● A direct connection between OUTPUT and INPUT

Ceiling-mounteddaylight sensor

EXAMPLE: daylight sensor controls interior lighting

Natural daylightthru windows

high natural light: ADJUST lighting

low/no natural light: ADJUST lighting

OUTPUT

●Closed Loop System: A control system with an automatic FEEDBACK loop

Open/Closed Loop Systems 8/8Below: 20 everyday technology systems/sub-systems

[1] Electric fan[2] Foot-operated gas pedal[3] Cell phone[4] Thermostat[5] Door bell[6] Food processor[7] Car cruise control[8] Lawn sprinkler system[9] Car automatic headlights[10] xBox /Playstation

[11] ‘Active’ noise-canceling headphones[12] Volume control on headphones[13] Window shade[14] Central Air Conditioning[15] Electric toothbrush[16] Car anti-lock braking system[17] Hair dryer[18] Traffic lights[19] Foot-operated brake pedal[20] Programmable croc pot w/temp probe

Which are Open-Loop Systems? – ‘O’ Which are Closed-Loop Systems? – ‘C’