A SYSTEM is any active device if left as open loop it will saturate one way or the other if the gain is ample. To control a system it must have some feedback to determine ts linear operating capabilities. As an example an airplane taking off at Las Vegas the cabin will be pressurised to -1000 feet from the ground and maintain a rate of climb to even 50.000 feet with a delta of 17 PSI The cabin pressure as a system will maintain this delta by close loop control otherwise we will need oxygen if flying. INTERESTING?
electric ovens/gas ring/water tap/traffic signals/washing machine/electric fan/irrigation sprinkler system/electric motor/manual operation of the accelerator in auto mobile/manual operation of brake system in an auto mobile.
An open loop system has no feedback to control its operation. For example, if you have a furnace that turns on when a certain low temperature is reached. The furnace heats the house, but there is no sensor to determine when the desired temperature is reached. It just keeps running until it is turned off manually. In a closed loop system the system would sense the desired temperature and automatically turn off.
There is also a principle called hysteresis. In the furnace example, you don't want the furnace to turn on immediately after it stops because of a small temperature drop. This delayed turn on feature describes the hysteresis in the system.
Ceiling fan,light bulb,washing machine,toaster etc.
A cellular phone Word processors Sprinkler system
Newspaper, Thermostat, Fridge, Air conditioner
air conditioner
a oven
a microwave
traffic signal,blind person,
Example of open-loop control system
traffic signal,blind person,
Closed loop: 1. Thermostat --> furnace (constant temperature) 2. Toaster setting (light/dark) --> toast (IF the toaster has heat sensors) 3. Refrigerator cold/hot setting --> refrigerator inside temperature (constant) 4. Temperature setting for oven (not stovetop) --> oven temperature constant 5. Clothes dryer with moisture sensor 6. Washing machine water level Furnace. Temperature sensors control when furnace is turned on. Heating sensors in furnace control when air blower is turned on, and when flames must be turned off. Refrigerator. Temperature sensors control when refrigerant cycle turns on and off. Many TV functions, internal operation of disc playback and record, really ad infinitum.
For very complex process control, such as used in the chemical industry, may require algorithms and performance beyond the capability of even high-performance PLCs. Very high-speed or precision controls may also require customised solutions; for example, aircraft flight controls.* Manufacturing Industry- Lead acid battery plant, complete manufacturing system- Extruder factory, silo feeding control system * Travel Industry- Escalator operation, monitored safety control system- Lift operation, monitored safety control system * Aerospace- Water tank quenching system * Printing Industry- Offset web press print register control system- Multi stage screen washing system * Food Industry- Filling machine control system- Main factory feed water pump duty changeover system * Textile Industry- Indutrial batch washing machine control system- Closed loop textile shrinkage system * Hospitals- Coal fired boiler fan change-over system * Film Industry- Servo axis controlled camera positioning system * Corrugating- Main corrugator machine control system- BOBST platten press drive and control system * Plastics Industry- Extruder factory, silo feeding control system- Injection moulding control system * Agriculture- Glasshouse heating, ventilation & watering system * Foundry- Overhead transportation system from casting process to shotblasting machine * Leisure- Roller coaster ride and effects control system- Greyhound track 'Rabbit' drive system
If I understand what you are asking, you are describing a steam cycle system. First water is pressurized and pumped via a condensate pump (the water is called condensate. This condensate normally goes through a heater to increase efficiency, then is further pressurized by feed pumps. The water (now called Feed Water) is then sent through a control valve and into a steam generator (basically a large tea kettle). The control valve maintains constant water level in the generator within a certain range. The water in the generator is heated by various ways (Oil, Coal, Nuclear, Geothermal or even Solar reflectors). The steam produced is directed to do whatever work the system is designed to do, either heating, electricity generation, propulsion (steam locomotive / Steam powered ship). Once the steam has been used to produce work, it is at a lower temperature and pressure than it was in the generator. This low pressure steam can be directed to the condensate heater (as described above) then to a condenser, or straight to the condenser. The condenser uses various ways to further cool the steam; (water, cooling towers ;those big towers at nuclear power plants) and the resulting condensate is collected to be reused. The reason why it is called a closed loop system is that the water is re-used time and again in a loop. The water is only added to make up for leaks in the system (thus it is called make up water).
A servo drive is any motor controller which uses a closed feedback loop to monitor the motors speed. This is normally accomplished through the use of an encoder or resolver.
closed loop system
A Closed loop system basically will have a feedback which enables the rectification of the error in the main process,whereas it is not possible in an open loop system
The closed loop control refers to a system whereby an input forcing function is usually determined in part by the system response.
Yes it is
yes
stability and repeatability
Open loop (single cycle) involves a break requiring a restart, easily adapted to closed loop.
The Nyquist stability criterion, named after Harry Nyquist, provides a simple test for stability of a closed-loop control system by examining the open-loop system's Nyquist plot. Under many circumstances, stability of the closed-loop control system may be determined directly by computing the poles of the closed-loop transfer function. In contrast, the Nyquist stability criterion allows stability to be determined without computing the closed-loop poles
A cruise control is an example of a closed loop servo.
open (in terms of thermo chemistry) ! It cannot be proved with science yet! BUT WHEN ONE TOUCHES SOMEONE, LOOKS THEM IN THE EYE, so forth one feels the exchange of energy(emotions). they are being effected by the surrounding !
A control system that appears to be self-regulating. Closed-loop systems employ feedback and a reference of correctness (norm or set point). Deviations from the norm are detected and corrections made in order to maintain a desired state in the system. Closed loop systems provide the homeostatic mechanism of many physiological functions (see negative-feedback) and also control some movement patterns, where feedback from proprioceptors and other receptors play an important part. Compare open-loop-system.
traffic signal,blind person,