Lesson 1 ( Sensors, Transducers and Actuators )
Lesson 2 ( Manual Auto Open Closed Good and Bad )
Explanation Temperature Room Control - Manual Automatic
Manual Control System
Switch on heater until desired output at which stage you switch off the heater - This is a manual control system. A person manually controls the room temperature.
Automatic Control System
(Option A) We could add a timer so it switched on and off at set time interval. Another option (option B) is to add a sensor and set the desired temperature output. The sensor will measure the diff between output temp and the desired temp. If output temp less than the desired temp the heater will work to increase the temp. If the temp becomes higher the heater will switch of until back to desired temp. Both are Automatic Control Systems.
In option A the input is entirely independent of the output of the system. As long as power supply is witched on the system will produce heat. The final room temperature has no control over the power supply of the system.
In option B the input is related to the output of the system. The heating element functioned based on the difference between desired and actual output temperature. The difference is cal the error of the system. The error difference is fed back to control in the input
Is Option A an Open or Closed control system ?
Is Option B an Open or Closed control system?
Open Loop Control System
Give Some Practical Examples of Open Loop Control System
Advantages of Open Loop Control System
- 1Simple in construction and design
- 2Low Cost
- 3Easy to maintain.
- 4Stable ( no bugs bmw cars)
Disadvantages of Open Loop Control System
- 1They are inaccurate
- 2They are unreliable
- 3Any change in output cannot be corrected automatically.
- 4Stable less likely to break as simple architecture
CLOSED Loop Control System
Control system in which the output has an effect on the input quantity in such a manner that the input quantity will adjust itself based on the output generated is called closed loop control system. Open loop control system can be converted in to closed loop control system by providing a feedback. This feedback automatically makes the suitable changes in the output due to external disturbance. In this way closed loop control system is called automatic control system. Figure below shows the block diagram of closed loop control system in which feedback is taken from output and fed in to input.
Practical Examples of Closed Loop Control System
- 1An Air Conditioner – An air conditioner functions depending upon the temperature of the room.
- 2Missile Launched and Auto Tracked by Radar – The direction of missile is controlled by comparing the target and position of the missile.
- 3Automatic Electric Iron – Heating elements are controlled by output temperature of the iron.
Advantages of Closed Loop Control System
- 1Highly accurate as any error arising is corrected due to presence of feedback signal.
- 2The sensitivity of system may be made small to make system more stable.( fine tune)
- 3Facilitates automation
- 4Less affected buy noise ( outside disturbance / unexpected
Disadvantages of Closed Loop Control System
- 1They are costlier.
- 2They are complicated to design
- 3Required more maintenance.
Feedback Loop of Control System
A Transducer is any device that converts one form of energy to another form
A sensor is a device that received and responds to a signal.
A device that actuates or moves something. Am Actuator is a specific type of transducer
Do BBC Micro Bit Activities
1 Code the micro bit pins to control switching and LED on and Off
2 Code the micro bit to use the temperature sensor. - display HOT if temp > 27 Else Display COLD ( take it outside to compare the outside and inside temperature ( hook up battery pack) )
3 Set up the micro bit light sensor to measure light and switch on and off the LED at a preset Light levels ( programmed )
4 Rock Scissors paper Complete this activity Click Here
Lesson 3 ( Distributed vs Central Systems )
Characteristics of Centralized System
Wikipedia. Consider a massive server to which we send our requests and the server responds with the article that we requested. Suppose we enter the search term ‘junk food’ in the Wikipedia search bar. This search term is sent as a request to the Wikipedia servers (mostly located in Virginia, U.S.A) which then responds back with the articles based on relevance. In this situation, we are the client node, wikipedia servers are central server.
Advantages of central system:
Disadvantages of central system:
In Distributed systems, every node makes its own decision. The final behaviour of the system is the aggregate of the decisions of the individual nodes. Note that there is no single entity that receives and responds to the request.
Google search system. Each request is worked upon by hundreds of computers which crawl the web and return the relevant results. To the user, the Google appears to be one system, but it actually is multiple computers working together to accomplish one single task (return the results to the search query)
Advantages of Distributed System
Disadvantages of Distributed System
Choose any electronic control systems and prepare a 10 minute presentation - Some Examples Below
I will post this on classroom : Mention all the key terms Sensor, Transducer, Actuator, Controller/Processor Reference Point ....
- 1Bio metric access control systems
- 2Home Control System
- 3Elevator control system
- 4Flood control System
- 5Air pollution control system
- 6Gate control system
- 7Washing Machine Control System
- 8keypad access control system
Lesson 4 ( Analog Digital Data Text Compression )
What is the difference between data and information
Data Basic values or facts. Information Data that has been organized or processed in a useful manner
What Types of media do Multimedia Devices Handle
Analog Digital Data
Data can be represented in one of two ways: analog or digital. Analog data is a continuous representation, analogous to the actual information it represents. Digital data is a discrete representation, breaking the information up into separate elements.
A continuous representation of data
A discrete representation of data
A mercury thermometer is an analog device. The mercury rises in a continuous flow in the tube in direct proportion to the temperature. We calibrate and mark the tube so that we can read the current temperature, usually as an integer such as 75 degrees Fahrenheit. However, the mercury in such a thermometer is actually rising in a continuous manner between degrees. At some point in time, the temperature is actually 74.568 degrees Fahrenheit, and the mercury is accurately indicating that, even if our markings are not detailed enough to note such small changes.
Why do we use Binary to represent data in a computer ?
- 1Less Expensive
- 2More Reliable
Representing Numeric Data
If positive integers it is simply a mapping from one number system to another.
A text document can be decomposed into paragraphs, sentences, words, and ultimately individual characters. To represent a text document in digital form, we simply need to be able to represent every possible character that may appear. The document is the continuous (analog) entity, and the separate characters are the discrete (digital) elements that we need to represent and store in computer memory
At this point, we should distinguish between the basic idea of representing text and the more involved concept of word processing. When we create a document in a word processing program such as Microsoft® Word, we can specify all kinds of formatting: fonts, margins, tabs, color, and so on. Many word processors also let us add art, equations, and other elements. This extra information is stored along with the rest of the text so that the document can be displayed and printed the way you want it. The core issue, however, is the way we represent the characters themselves; therefore, those techniques remain our focus at this point.
The ASCII ( American Standard Code for Information Interchange) (7/8) bits per char
ASCII stands for American Standard Code for Information Interchange. The ASCII character set originally used seven bits to represent each character, allowing for 128 unique characters. The eighth bit in each character byte was originally used as a check bit, which helped ensure proper data transmission. Later ASCII evolved so that all eight bits were used to represent a character. This eight-bit version is formally called the Latin-1 Extended ASCII character set. The extended ASCII set allows for 256 characters and includes accented letters as well as several other special symbols
The Unicode Character Set ( the encoding uses 16 bits per character )
For consistency, Unicode was designed to be a super set of ASCII. That is, the first 256 characters in the Unicode character set correspond exactly to the extended ASCII character set, including the codes used to represent them. Therefore, programs that assume ASCII values are unaffected even if the underlying system embraces the Unicode approach.
- 1Keyword encoding
- 2Run-length encoding
- 3Huffman encoding
Replacing a frequently used word with a single character
Replacing a long series of a repeated character with a count of the repetition
Using a variable-length binary string to represent a character so that frequently used characters have short codes
Try Encoding ? What is the Compression Ratio ?
The human body is composed of many independent systems, such as the circulatory system, the respiratory system, and the reproductive system. Not only must all systems work independently, but they must interact and cooperate as well. Overall health is a function of the well-being of separate systems, as well as how these separate systems work in concert
flag character, followed by the repeated character, followed by a single digit *A7
Then the word “DOORBELL” would be encoded in binary as 1011110110111101001100100
If we had used fixed length string (8 Bits ) how many bits to represent ?
Decoding Hoffman Coding
An important characteristic of any Huffman encoding is that no bit string used to represent a character is the prefix of any other bit string used to represent a character. Therefore, as we scan from left to right across a bit string, when we find a string that corresponds to a character, that must be the character it represents. It can’t be part of a larger bit string
So how is a particular set of Huffman codes created?
Beyond scope of IB