7 Discuss a range of control systems Flashcards
7.1.1
Explain control systems
A control system is a device, or set of devices, that commands and regulates the behaviour of other devices using control loops.
They are set up once and can then perform the actions they have been programmed to do in an automatic manner, so it can operate without human intervention.
7.1.1
Explain open and closed loop systems
Open loop: the output is not fed back into the system as input. So the control action does not affect the input.
Closed loop: the output is fed back into the system as input, creating a feedback loop. That is to say, the control action affects the input.
7.1.1
Discuss the features of automatic doors as a control system
- Motion sensors are typically located at the top of the automatic door, allowing the control system to be aware of any motion.
- The sensor might use infared or microwave signals that bounce off objects to determine motion.
- After receiving feedback from the environment, the sensor forwards its signal to a microprocessor and allows the control system to operate its actuators to open the doors.
- Automatic doors are efficient, as it saves a lot of effort. Moreover, automatic doors allow access to the elderly and disabled, who may otherwise find it difficult to open or close manual doors.
7.1.1
Discuss the features of heating systems as a control system
- An initial ideal temperature is given as input by the user, which becomes the heating system’s goal.
- Temperature sensors allow the control system to measure the tempearture of the environment. Then, the control system can compare the current temperature with the ideal temperature and decide if output is needed.
- If the temperature is too low, the control system would turn on the heater until the ideal temperature is reached.
- Having such a control system saves time as you don’t have to turn it on and off manually. It also conserves energy because the heater will only be on when necessary.
7.1.1
Discuss the features of taxi meters as a control system
- A taxi meter is a device installed in taxicabs to caculate passanger fares based on distance travelled and wait time.
- A timer measures the amount of time elapsesd.
- Distance sensors measure the distance the taxi has travelled.
- Receipts are automatically issued when a fare is completed.
7.1.1
Discuss the features of elavators as a control system
- Input buttons indicating the correct floor
- Input indicating the current floor (so the distance needed to travel can be calculated)
- Turns a winch motor the correct number of revolutions so the elavator car reaches its destination.
- Elavators typically use automatic doors
7.1.1
Discuss the features of washing machines as a control system
- Sensors are used to determine the control and load size, water level, temperature.
- The user interface such as buttons, dials, or touch screens allow the user to input their preferences
- Output transducers include motors that spin the tub, water pumps that remove water, heating elements to heat the water.
- It also conserves energy by consuming less electricity and water.
7.1.1
Define process control
Process control is the ability to monitor and adjust a process to give a desired output. It strives to maintain the output of a specific process within a desired range.
7.1.1
Define device drivers
These device drivers allow operating systems and other programs to communicate with the devices with a layer of abstraction (it does not need to know how the actual devices are used).
7.1.1
Define the features of domestic cleaning robots as a control system
- Using cameras or LIDAR, they can create house maps, locate themselves within the map, and detect obstructions in front of them.
- Touch sensors indicate when contact is made to the floor.
7.1.1
Define the features of GPS systems as a control system
- GPS systems are needed to help navigate individuals or objects to their correct destination.
- Many satellites orbit around the Earth which know their individual positions around the Earth.
- A GPS receiver locates four or more of the GPS satellites, and locates its own position through a principle called trilateration.
- Satellites continously transmit signals that include the time the signal was sent and its position at the time. GPS receivers pick up these signals
- Using the satellites positions and the time taken for the signal to reach the GPS receiver, the device can perform trilateration calculatrions to figure out its position.
7.1.1
Define the features of traffic lights as a control system
Traffic lights can either be fixed time or dynamic control.
Fixed time: They are open loop control systems which are configured to change colour after a certain time period and do so repeatedly.
Dynamic control: They are closed loop control systems to provide feedback on the amount of traffic passing by. If there is a lot of car traffic, the light may adjust their traffic settings appropriately.
They can use one of the two different types of sensors to detect traffic conditions: sensors embedded onto the road to sense when a car passes over it, or mounted sensors on the traffic light to detect motion.
