Open loop control systems
Open loop systems usually require open loop controllers which usually help to achieve a
specific task. Most of the time the open loop system looks at the input for it to know what it
needs to achieve however the output is usually not important for the system. The
advantages of an open loop control system are its easy to maintain, generally stable,
economical, simple design and construction and is low cost. The diagram below shows a
brief example of how the open loop control system would work however it is very basic.
Some examples of where these kind of systems can be used can be switching on a light bulb,
the input would be you switching on the light bulb and the output would be the light bulb
on. Other devices that could use this would be tumble drier, remote controls, stepper
motors, washing machine etc.
Closed loop control systems
Closed loop systems also have to achieve specific tasks however it usually monitors the
input and output to make sure it’s actually met. Of course if it’s not met usually it will
automatically fix its self and will keep doing so, this is done by a sensor to monitor the
output and will adjust accordingly to reduce the amount of errors and achieve the desired
outcome. The advantages of closed loop control systems are bandwidth is higher range,
more accurate, automatic however some disadvantages can be its more costly, more
maintenance and less stability.
Examples of were these systems are required could be heating system where the input
would be you switching the boiler on and the output would the radiators giving out heat,
however with a closed loop control system there would be a sensor in place such as a
thermostat to measure the temperature of the room if it’s too warm it will switch the boiler
off and if it’s too cold it would switch the boiler off. Many other devices that use this can be
water level control, air conditioner, cooling system in car etc.
Loop stability
Both open and closed systems used ‘Loops’ to control the system and make sure it’s always
stable. With loop stability the system is less likely to be error prone and can function for how