Unit 24 Assignment 1

Unit 24: Controlling Systems Using IT 

P1 Explain the types of control systems 

Command Systems 

A command system is a device which requires input from the user to perform some sort of function that the user executed on an electronic device. For example, a TV remote is an example of a command system as when a user presses the volume button the remote will send a radio signal to the TV executing the adjust volume function on the TV.  

Picture reference: https://www.forbes.com/sites/annatobin/2018/10/05/is-the-tv-remote-control-soon-to-become-extinct/?sh=6226831d19be 

Programmable Systems 

A programmable system is a system which allows the user to program a list of instructions into that system which it will follow to carry out the task. For example, a microwave is an example of a programmable system as you are telling it various instructions such as how long to microwave for, what temperature, what mode like to defrost, the weight of the food and so on. 

Picture reference: https://www.amazon.co.uk/YC-MS02U-S-Digital-Microwave-Capacity-Programmes/dp/B07Y2CS337 

Sensing Systems 

A sensing system is a system which responds to changes in the environment that the sensor detects. The response is dependent on the device that is controlling it may perform various things. For example, a building may have a light sensor that will detect the temperature of the room by using a thermostat in conjunction to measure the temperature. If it detects the temperature as not having any people in it then it will switch off the light. This saves energy and reduces electricity bills as the light is only being activated when are people are present in the room. 

Picture reference: https://www.asmag.com/showpost/30803.aspx 

Conditional System 

A conditional system is a system which makes logic-based decisions based on what the input it receives to perform the operations that was given to it. The inputs can range from sensors, direct user input, being a specific date or time. The logic is binary in the sense that if the input it receives input that meets a certain condition it will perform the operation otherwise it will do nothing, or the set of steps given to it when that condition is not me. For example, a smart lock is an example of a conditional system as some version have a keypad where the user with manually input their pin, then the smart lock will check if the pin is correct, which in this case it will open. If the pin is incorrect then it will show a flashing red light as an error and if the pin attempts fail too many times, then it may block any codes from being entered. 

Picture reference: https://www.postscapes.com/smart-lock-with-keypad/ 

P2 – Explain the characteristics of digital and analogue control systems 

Digital 

Microcontroller device selection 

A microcontroller is a small computer which is embedded into some other device, they typically perform one function repeatedly by interpreting the data that it receives from its I/O peripherals using its central processor. They are low power using up to 50 milliwatts of energy and in some cases have a small LED or LCD display to act as output. They are also low cost meaning that they will be inexpensive and relatively cheap to buy. They also contain an ADC and DAC, system bus to link all the components and a serial port to connect the microcontroller to the other external components. 

An example of a microcontroller would be the Arduino 

Picture reference: https://www.distrelec.biz/en/microcontroller-board-uno-arduino-a000066/p/11038919 

(Author: Margaret Rouse, Created: Unknown, Accessed: 13/01/2021) 

https://internetofthingsagenda.techtarget.com/definition/microcontroller

Basic system design 

The basic system design is the digital circuit design which is used in some electronics. The digital circuit is composed of logic gates such as Not, AND, OR, XOR, NAND, NOR, XNOR which are used to perform Boolean operations. These gates can be combined to form more complex arrangements in order to become components such as flip-flops, counters, registers, multiplexers and demultiplexers, and arithmetic logic units. These components can then further be combined with regular gates to form a CPU. 

Picture reference: https://www.indiamart.com/proddetail/digital-circuit-board-21749581555.html 

(Author: Tom Crosley, Updated: January 30 2019, Accessed: 13/01/2021) 

https://www.quora.com/What-is-the-difference-between-embedded-systems-digital-design-and-analogue-design

Speed 

Digital systems are the more common ones that you find nowadays in electrical devices like your computer. To represent data a digital system will use on or off values such as 1 or 0 equivalent to true or false. Digital signals travel at the speed of which the medium they are travelling through. In most cases digital signals are transmitted as either light, radio waves or electrical signals.  

When travelling as light, the speed at which they travel through the wire depends on the velocity factor of the cable.  

When travelling as radio waves they can travel forever but with the catch that as the distance increases the power is being reducing and at a certain point you cannot retrieve the information with good accuracy 

Picture reference: https://learn.adafruit.com/circuit-playground-digital-input/digital-signals 

(Author: Bob HannetCreated: June 28 2016, Accessed: 13/01/2021) 

https://www.quora.com/How-far-and-how-fast-can-digital-signals-travel

Memory requirements 

For digital information to automatically pass on then it will need memory to be able to store its data. In some digital control systems there are instructions that must be automatically run because they have essential things they need to do so they will executed automatically. The complexity of the job is a prime factor of how much memory in bytes will be needed to store the digital information. 

Picture reference: https://www.researchgate.net/figure/a-The-von-Neumann-architecture-b-digital-signal-in-computer_fig2_328083598 

Number of I/O ports needed 

The number of input and output ports needed can vary depending on which digital system is being referred to. On the Arduino board it has three ports, B which has digital pin 8 to 13, C which are analogue input ins and D which are digital pins 0 to 7. These pins can be used as either input or output. 

Picture reference: https://www.electronoobs.com/eng_arduino_tut12.php 

Digital to analogue devices 

A digital to analogue converter is a device which can convert binary values to continuous analogue voltages. The DACs are important for translating the binary into video, audio and any other sensory data. A common use case of a DAC is to convert the digital source of music into an electrical output for an audio player to play.  

There are three main types of DAC which are: Summing Amplifier, R-2R Ladder and PWM DAC. The effectiveness of a DAC can be evaluated by a list of criteria such as: resolution, speed, monotonicity, dynamic range and digital to analogue converter architectures.  

The DAC you decide to use will depending on what you are using it to decode, how much data will it have to process and whether the speed or resolution is more important in your case, how many output channels will be required. 

Picture reference: https://www.amazon.com/PROZOR-Digital-Converter-Optical-Toslink/dp/B00KNNSKV0 

(Author: Unknown, Created: Feb 4 2019, Accessed: 13/01/2021) 

https://www.arrow.com/en/research-and-events/articles/dac-buying-guide-find-the-best-digital-to-analogue-converter

Analogue 

Signal conditioning

Analogue signals will need to go through a preparation stage before they become digitalized. Signal conditioning is an electronic circuit which manipulates a signal in a way that will prepare it for the processing stage. A data acquisition system basically makes physical measurements, many sensors will require signal conditioning done prior before a data acquisition device will accurately and effectively measure the signal. 

(Author: Unknown, Updated: March 5 2019, Last Accessed: 13/01/2021) 

https://www.ni.com/en-gb/innovations/white-papers/09/what-is-signal-conditioning-.html

Noise filtering 

In analogue signal processing, a noise filter is a process which removes the unwanted noise from the signal. It does this by removing some of the frequencies and not certain others which as a result will suppress the interfering signals and it will also reduce the background noise so you can then capture the important relevant signals. 

Picture reference: https://medium.com/blueeast/how-to-use-moving-average-filter-to-counter-noisy-data-signal-5b530294a12e 

Level-shifting 

A level shifter is a circuit which will translate logic signals from one level to another. This translation of signals from one logic level to another will allow compatibility between integrated circuits that have different voltage requirements. Typically, this shift will take place in between –5V and 5V. There are two types of level shifting that can take place, bi-directional which allows signals to travel back and forth and the other is uni-directional which allows signal to travel in one direction only. 

Picture reference: https://www.arrow.com/en/research-and-events/articles/using-a-level-shifter-to-integrate-different-voltage-signals#:~:text=A%20level%20shifter%20translates%20logic,2.5V%20or%201.8V.&text=%2D%20What%20voltages%20are%20available

(Author: Unknown, Created: July 10 2019, Last Accessed: 14/01/2021) 

Matching to sensors 

Matching is the process of collecting the correct frequencies for a given converter. Therefore, a correct sensor must be used in order to assist in collecting the frequency of choice and must be matched to the chosen converter in order to accurately receive and interpret the signal. 

Picture reference: https://www.electronics-tutorials.ws/io/io_1.html 

ADC devices 

An analogue to digital converter works by taking a snapshot of an analogue voltage at a point in time and then will encode it to output a digital code which will represent this analogue voltage quantitatively. The measurable performance of an ADC is determined by its bandwidth and its signal to noise ratio. The bandwidth mainly depends on its sampling rate whereas the signal to noise ratio is influenced by several factors. These factors include: the resolution, linearity and accuracy as converting a continuous signal into a quantitative figure will create a small amount of error, aliasing and jitter. 

Picture reference: https://www.electronics-tutorials.ws/combination/analogue-to-digital-converter.html 

P3 – Illustrate the operation of different sensors and output devices 

Sensors 

Choosing sensor 

Picture reference: https://www.electronicshub.org/different-types-sensors/ 

Choosing the right sensor for your situation can be tricky but there are some factors that when taken into consideration will guide you into picking the right one. 

First to determine which sensor you will pick you should focus on what your sensor will be sensing. Will your sensor be looking sense an object existing, the distance between the sensor and the object, the position of the object, another signal like the temperature, pressure or flow? 

Second you should decide if the sensor will be able to cope in the environment it is placed in and consider how it would respond in extremer conditions. 

Thirdly take into consideration the range of the sensor, you need to know if the range of sensor will impose a constraint on its task such as sensing a target from far away. 

Fourthly you should be aware of the physical space surrounding your sensor and if that is enough or too little to achieve the most optimal results for your sensor. 

Fifth make sure that the sensor you select has good accuracy, you want the sensor to be accurately measuring things such as the temperature, distance to a target otherwise you will get incorrect information which can significantly affect your decisions based on these results. 

These are a just a few of the many factors that should be thought about when choosing a sensor. 

Sensor Type 

Picture reference: https://plumbingsuppliesdirect.co.uk/honeywell-t6360-central-heating-room-thermostat/ 

There are many different sensor types that work in different ways. For example, a heat sensor such as a thermostat works by containing either a bi-metal coil or a metal strip. The coil or strip will move when there is a change in the temperature, thus causing a vial that contains mercury to tip over to one side. Due to the mercury flowing to one end of the vial this signals that heating or colling will need to turn on. 

Another is a light sensor which are present in our mobile phones. These light sensors will measure the illuminance around the phone. By detecting the lighting levels in the area, it will adjust the brightness on our display accordingly to match. 

Picture reference: https://www.gearbest.com/blog/how-to/2-types-of-phone-sensors-and-hot-plugging-2787 

Linear position 

Picture reference: https://www.althensensors.com/sensors/linear-position-sensors/ 

Linear position sensors are sensors which use either contact or non-contact methods to either measure the speed of an object in linear motion or the determine the position of an object.  These sensors use several different technologies in combination to perform this task, but the general method used by most sensors will typically involve emittance which is interfered by the target. The interference will be recorded and translated into a measure of the velocity or distance of the target and then converted into electrical output signals so it can be processed. The format of the electrical output signal will depend on the sensor. 

Linear position sensors have their applications and uses in many things that you see in everyday life such as: steering systems on machinery, wheelchair steering systems, shock absorber on professional mountain bikes, electric cart throttle control and more. 

Shaft Position 

Picture reference: https://www.amazon.com/Valvetronic-Eccentric-Sensor-Engine-Variable/dp/B076J96NXJ 

A shaft position sensor is an electronic device which is used in an internal combustion engine in order to keep an eye on the rotation speed and position of the crankshaft. The engine management systems will have this information passed over to it in order to control the fuel injection or the ignition system timing and other engine parts. The output from the sensor could possibly be related to other sensor data such as the cam position to derive the current combustion cycle. 

After extreme or extensive use, the shaft position sensor can become burnt or worn out. This will cause the shaft position to failure and in most cases is due to the exposure of extreme hearts. As a result of this it can worsen the way an engine idles or the acceleration behaviour, in worst case the car may not be able to start at all. 

Switch 

Picture reference: https://venturebeat.com/2017/01/12/nintendo-switch-has-high-tech-joy-con-controllers-with-motion-detection/ 

The switch comes with two joy-con controllers. Each of these joy-con controllers contains a camera and motion detection as well as an accelerometer and gyro-sensor. This allows the player to be able to make independent left and right motion movements detectable individually. The right joy-con controller is embedded with an infrared motion camera that is used to determine the distance, shape, and motion of nearby objects in specially created games. For example, it can measure how far away the user’s hand is and if the hand is forming some sort of shape such as rock, paper, or scissors.  

Electrical characteristics of sensors 

Picture reference: https://www.electrical4u.com/characteristics-of-sensors/ 

The electrical characteristics of sensors include: sensitivity, resolution, span, linearity, range, repeatability, reproducibility, and response. 

Sensitivity is the measure of the ratio change in output of a sensor relative to a unit change in the input. 

Resolution is the smallest amount of change in the input which can be sensed by the sensor.  

Span is the difference between the maximum and minimum values a sensor receives as input. 

Linearity is the maximum deviation between the measured values of a sensor from an ideal curve. 

Range is the lower and upper bound of limits that the sensor can measure from its input. 

Repeatability is the consistency of the sensor of producing the exact same output in every case where the same input is applied and all other factors such as the physical and measurement conditions are kept the same under a short time interval. 

Reproducibility is the consistency of the sensor of producing the exact same output in every case where the same input is applied but it is either: taken over a long period of time, performed by different operators, with different instruments or in different laboratories. 

Response is usually defined as the time at which it takes for the output to reach a specific percentage of its final value, in response to a step change of the input. 

(Author: Electrical4U, Updated: October 28 2020, Accessed: 16/01/2021) 

https://www.electrical4u.com/characteristics-of-sensors/

Output devices

LCD Displays 

Picture reference: https://www.philips.co.uk/c-p/243V7QDAB_00/full-hd-lcd-monitor 

LCD screen work by having millions of tiny dots which are formally known as pixels. These pixels each contain a red, green and blue light filter which are adjusted in order to create the correct colour to display on the screen. This works because inside of each pixel there are liquid crystals which are able to be manipulated to control how much of fluorescent tube backlight goes through to the individual RGB filters on the display.  

Lamps 

Picture reference: https://www.ikea.com/gb/en/p/arstid-table-lamp-brass-white-60321376/ 

A lamp is a shade with a lightbulb which basically works by containing an extremely small thin filament of tungsten, which is difficult to melt. It is in most of the time encased in a glass bulb that is filled up with inactive gases in order to stop the filament from oxidising and disintegrating. The electricity from the supplies will then cause the wire to glow and a part of that energy is converted into light. However, the problem is that the majority of energy that causes the wire to glow is actually converted into heat which is wasteful and can cause the bulb to burn out if left on for extensive periods of time. Therefore, LED lights are slowly become the preferred choice in terms of lighting options. 

Relays 

Picture reference: https://www.electgo.com/what-is-a-relay/ 

A relay is an electromagnetic switch that’s purpose is to open and close circuits electronically as well as electromechanically. A relay basically controls the opening and closing of the circuit contacts of an electronic circuit. When a relay contact is normally open there is an open contact when the relay is not energized, on the other hand, when the relay contact is normally closed there is a closed contact when the relay is not energized. In both situations, applying electrical current to the contact will change their state. 

(Author: Unknown, Created: October 17 2019, Accessed: 17/01/2021) 

https://www.electgo.com/what-is-a-relay/

Motors 

Picture reference: https://www.indiamart.com/proddetail/siemens-electric-motor-16291561291.html 

An electric motor will work by converting the electrical energy which it receives into mechanical energy that is used to create motion. Due to the interaction between the magnetic field and winding alternating current or direct current a force will be generated within the motor. The strength of the magnetic field goes up as the strength of the current does. 

Solenoids 

Picture reference: https://passive-components.eu/solenoids-explained/ 

A solenoid is a device that is made up of three components: a coil of wire which when an electrical current flow through will create a strong magnetic field, housing that is typically made of iron or steel which will surround the coil concentrating the magnetic field created and a plunger which is attracted to the stop through the concentration of the magnetic field allowing the mechanical force to do work. When an electrical current is introduced to a solenoid a magnetic field will form around the coil which in turn draws the plunger in, essentially a solenoid converts electrical energy into mechanical work. 

Interfacing with controllers 

Picture reference: https://www.elprocus.com/types-interfacing-devices-applications-with-microcontroller/ 

Interfacing with controllers can be expressed as transferring data between microcontrollers and other interfacing peripherals for example, sensors, LCD displays, motors, ADC, other microcontrollers and so on. Devices that interface with microcontrollers are that used to perform a special task are named ‘interfacing devices. Interfacing is a technique that has been developed and built upon in order to solve several composite problems in circuit design with factors taken into account such as: reliability, availability, cost, power consumption, size, weight and many more.  

M1 – Compare Analogue and Digital signals 

Picture reference:   https://digestiblenotes.com/physics/electricity_and_waves/analogue_and_digital.php 

An analogue signal is continuous with varying patterns. It is not one discrete value like in a digital system. A digital signal is a discrete timed signal which can only represent either 0 or 1 which is known as binary values. 

Analogue systems will use a continuous range of values to output information instead of a set range. A digital system uses two specific quantitative values to store information which can only be 1 or 0. 

Typical examples of analogue systems would be temperature sensors, FM radio signals, light sensor, watches, clocks, broadcast TVs. Typical examples of digital systems would be digital clock, CD, DVDs, computers, digital TVs, smartphones. 

An analogue system when recording analogue signals will store them as sine waves which represent physical measurements in real time which is low bandwidth. A digital system generates time separated signals by using digital modulation meaning it usually cannot be done in real time and the bandwidth is high. This makes analogue more suited for audio and video transmission whereas digital is more suited for computing and digital electronics. 

Analogue signals gradually get worse through transmission and the read/write cycle because of unwanted noise which is why they have to go through the signal conditioning process. Digital signals do not deteriorate through transmission and the read/write cycle because of their noise immune system. Digital instruments will never create any observational errors whereas analogue instruments tend to have a scale that is more cramped towards the lower end making it give some significant observational errors. 

Advantages of analogue signals 

  • It is low in cost and very portable 
  • It has a higher density therefore making it output polished information   
  • Use lower bandwidth than digital signal 
  • Better for video and audio 
  • There is no need to buy a new graphics board 

Disadvantages of analogue signals 

  • Quality is lost relatively easy especially at longer distances 
  • Hardware does not offer flexible implementation 
  • There are limitations when editing the signals 
  • Analogue cables are sensitive to external factors 
  • It is quite tricky to synchronize analogue sound 

Advantages of digital signals 

  • Digital data is easy to compress 
  • There are several editing tools available to use 
  • Easy to transmit the data over network 
  • The equipment that utilizes digital signal is more common and cheaper 
  • Information that is stored in the digital format can be encrypted 

Disadvantages of digital signals 

  • It uses up much more bandwidth 
  • The sampling can cause some loss of information when the digital modulation takes place 
  • The processor speed is limited 
  • Digital systems and processing are usually more complex 
  • ADC and DAC require mixed-signal hardware 

(Author: Unknown, Created/Last Updated: Unknown, Accessed: 14/01/2021) 

https://www.guru99.com/analogue-vs-digital.html

M2 Explain the need of signal conversion 

Picture reference: https://electronics.howstuffworks.com/cd.htm

All signals in the real world are analogue in nature, this includes light, sound, temperature, voltage, current, pressure and many more. Most of these signals however need to be converted to digital because of our current technology it is more advantageous for it to be digital as it greatly faster to process. In order to do this, we have analogue to digital converters which take care of the complex process of converting analogue to digital.  

One of the main reasons why we need to convert analogue signal to digital is to avoid the degradation and corruption of the signal. For example, on a vinyl record a needle is utilized in order to create grooves which is the recorded information of the desired music. However, the pressure created by these needles will gradually wear away the groove over time which causes the information to degrade/become corrupt. This is why CDs are preferred and used traditionally today as they digitally store the data eliminating all of these problems. 

Another reason is to be able to store pictures. When you use a camera to take a picture the sensor in the camera will convert light photons into electrons, each of the millions of sensor pixels build up an electric change that is equal to the number of photons that were collected. After a photo has been taken and the sensor has been exposed to light the charge from each individual pixel gets read out and converted to a voltage which is an analogue signal. This analogue signal then gets converted into a digital format so it can be stored on a SD card or any other form of memory storage. 

It’s also very important when capturing sound. For example, when you are talking on the phone your microphone will pick up the analogue sound signals and with the help of an analogue to digital converter piece of hardware it can convert it to a digital format which is easier to deal with for computers and will then get sent over the world to the destination phone, this destination phone will then reverse the process by using a digital to analogue converter to play it aloud for the person on the other end. 

 Also, when you want to listen to a song that song when recorded was initially analogue signals that were converted to digital through the use of an ADC in order to be stored on a computer hard drive, when you play the song just like before the process will be reversed so the music can be played just like how it was initially recorded. When it comes to digital data there are several different compression algorithms that can be used to shrink the signal. 

(Author: Marshall Brain, Created/Last Updated: Unknown, Accessed: 14/01/2021) 

https://electronics.howstuffworks.com/cd.htm

Bibliography 

(Author: Margaret Rouse, Created: Unknown, Accessed: 13/01/2021) 

https://internetofthingsagenda.techtarget.com/definition/microcontroller

(Author: Tom Crosley, Updated: January 30 2019, Accessed: 13/01/2021) 

https://www.quora.com/What-is-the-difference-between-embedded-systems-digital-design-and-analogue-design

(Author: Bob Hannet, Created: June 28 2016, Accessed: 13/01/2021) 

https://www.quora.com/How-far-and-how-fast-can-digital-signals-travel

(Author: Unknown, Created: Feb 4 2019, Accessed: 13/01/2021) 

https://www.arrow.com/en/research-and-events/articles/dac-buying-guide-find-the-best-digital-to-analogue-converter

(Author: Unknown, Updated: March 5 2019, Last Accessed: 13/01/2021) 

https://www.ni.com/en-gb/innovations/white-papers/09/what-is-signal-conditioning-.html

(Author: Unknown, Created: July 10 2019, Last Accessed: 14/01/2021) 

https://www.arrow.com/en/research-and-events/articles/using-a-level-shifter-to-integrate-different-voltage-signals#:~:text=A%20level%20shifter%20translates%20logic,2.5V%20or%201.8V.&text=%2D%20What%20voltages%20are%20available.

(Author: Electrical4U, Updated: October 28 2020, Accessed: 16/01/2021) 

https://www.electrical4u.com/characteristics-of-sensors/

(Author: Unknown, Created: October 17 2019, Accessed: 17/01/2021) 

https://www.electgo.com/what-is-a-relay/

(Author: Unknown, Created/Last Updated: Unknown, Accessed: 14/01/2021) 

https://www.guru99.com/analogue-vs-digital.html

Author: Marshall Brain, Created/Last Updated: Unknown, Accessed: 14/01/2021) 

https://electronics.howstuffworks.com/cd.htm

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