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But what are they and how do they work?
But what are they and how do they work?
Control technologies are all around us. They are in our homes, classrooms, shopping centres and even in our streets!
Traffic lights function by using a timer for busy intersection or sensors on the road to send a signal to the lights that there is a car waiting. Once the light sequence activates, the green light is on for a set amount of time then it turns off and the yellow light is on for a shorter period of time, followed by the red light. The system re-activates by a time sequence or again once a care pulls up and the sensor sends a signal again and repeats the sequence
A refrigerator uses a temperature sensor which detects the current temperature. If the temperature is higher than the specified temperature, the compressor starts up to cool the air to the required temperature. This is the whirring sound you hear when the fridge is on. The compressor turns off when the set air temperature is met and restarts as soon as the temperature rises again.
A dishwasher is programmed to complete a series of different functions e.g. rinse, heavy duty wash, regular wash, eco wash etc. Each process in programmed and connected to a different input (button) so when a particular button is pushed, it tells the dishwasher which process/cycle to perform. Some buttons when pushed include a combination of different cycles and the dishwasher is programmed to follow this sequence.
Televisions
The signal sent from the remote control is captured by the Television microcontroller. The microcontroller controls the television amplifier subsystem (for example, volume, base, and treble), the picture subsystem (for example, brightness , hue, and contrast), and the receiver subsystem (channel selection).
* Other products that have control technology
Home: DVD player, Sound systems, Telephone, mobile phones, security systems, camera, sewing machine, musical instruments, exercise machines, video games consoles (Play station), Personal computers, fridges, microwave oven, cable boxes (Foxtel)
Office: Computers, printers, telephones, fax machines, security systems, air conditioners, mobile phones, pages, display boards
Tickle me Elmo
Tickle me Elmo
The Circuit in a remote control is made up of:
The Circuit in a remote control is made up of:
•power supply (battery)
•input devices (buttons) - Rubber membrane keypad under each key is a conducting material which bridges contacts on the PCB when pressed. i.e. closes the circuit and electricity can and does flow.
•output device (infrared LED)
•wires (to transmit the flow of current from the battery to the inputs and outputs)
•Printed Circuit Board (PCB) (a board that holds components in place)
•Microcontroller (can be thought of as small computers to control systems).
•Note: If you have a tactile example that you can pull apart to show as an example, this is also useful.
Is it the microcontroller that makes this device a control technology? By itself, NO as one can envisage a microcontroller running but not controlling anything. Control technology requires at a very minimum a ‘Processor” and a ‘Output device’. For the example above, the microcontroller is what controls the Infrared transmitter and therefore makes the device a control technology.
The input device/component receives information from it’s environment and sends the information to the processer which is programmed to send instructions to the output device/component (actuator) to perform a certain task.
There are many different sensor and actuator technologies which we will be looking at in more detail throughout this unit.
Processor Technology options include:
•Microcontrollers
•Microprocessors
•Personal computers (laptops, desktops, tablets, etc.)
•Mechanical devices (for example, pneumatic)
•Electronic circuits that do not contain microcontrollers or microprocessors
Note: There are control systems that do not have inputs, however all control systems will have an output, otherwise it will have nothing to control.
Input Processing Output (IPO) charts
Input Processing Output (IPO) charts
Component categories for hardware:
Component categories for hardware:
IPO for Automatic sensor light
IPO for Automatic sensor light
An outdoor sensor light on a house works by the sensor detecting movement, sending a signal to the microprocessor. The microprocessor then turns on the light to illuminate for a set period of time. The system will reactivate once the sensor detects movement again.
IPO for Automatic Headlight
IPO for Automatic Headlight
Sensor detects low levels of light e.g. driving through a tunnel, driving at dusk, and sends a signal to the microprocessor which turn on the headlights. When there is increase in light detected in the environment, the lights turn off.
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