1 - Basics Of Cybernetics Flashcards
(36 cards)
The object of cybernetics
Cybernetics = the study of control and connections in nature, science and society Basic concepts: - organization - information - control
Cybernetic Systems
Organization - definition
System theory = the study of systems in general, with the goal of elucidating principles that can be applied to: - all types of systems - at all nesting levels - in all fields of research Organization = formation of systems
Cybernetic systems
Cybernetic system - definition
Cybernetic system = interacting structures and processes combined for the execution of a common function. Which function is diff from functions of the separate components
General properties of cybernetic systems:
- interact with environment and with other systems - connections
- have hierarchical structure - consists of subsystems
- preserve their general structure in changing environmental conditions
Cybernetic systems
Types of systems by complexity
3 types:
- component states
- structure and connections
- transmitted signals
Cybernetic systems
Types of systems by the degree of determinism of their response
- Deterministic = components act in a predetermined way and response is predictable e.g. machine
- Probabilistic = response can not be exactly predicted e.g. weather
Cybernetic systems
Type of systems by the type of interaction with the environment
- Closed = the components interact with each other only and no interactions with the environment
- Open = the components interact with the environment as well
Cybernetic systems
Elements of the interaction
- perception of signals from other systems using sensors (receptors) e.g. eyes, ears etc
- transmission of signals to other systems using effectors e.g. organs of speech, gestures etc
Cybernetic systems
Biological cybernetic systems - properties
Characteristics: - varying complexity - probabilistic - multi-level hierarchical organization Basic properties: - self-organization - self-regulation
Cybernetic systems
Biological systems - complexity
Very complex:
- large number of components
- complex and interrelated connections between components
Cybernetic systems
Biological systems - determinism
Probabilistic:
- large number of components
- large number of connections between the components
- strong external influences
Cybernetic systems
Biological systems - organization
Complex 2-way hierarchy
- low level components = perform independently of the higher level components as long as they are able to process all the important input info
- high level components = control the lower level components
Information theory
Information - definition
- any set of related data
- any meaningful event, which results in an action
- the state of a system of interest
Info reduces ambiguity and lack of knowledge
Information theory
Transmission of information - messages, signals and channels
Message = the transmitted info
Signal = the physical carrier of the message
Communication channel = the medium in which the signal propagates
E.g. sound wave (signal) - air (channel)
Information theory
Alphabet (code), encoding, recording, decoding
Alphabet = a set of simple signals which can be used to send any message
Encoding (by transmitter) = generation (using an alphabet) of a signal which carries the message
Recording = altering the alphabet
Decoding (by receiver) = extraction of the message from the signal
Information theory
Isomorphism and noise, signal-to-nose ratio
Isomorphic signals = physically diff signals which carry the same message
Noise = communication system disturbances which modify the signal
Information theory
Storing and retaining information
Memory = the ability of a system to store and retain info, and to recall it for use at a later moment
Ways to memorize info:
- change the states of system components
- change the structure of the system
Information theory
Measuring information - the bit
Unit of measurement = the bit
One bit is the amount of info received when we learn which one of 2 equally likely events has occurred e.g. tossing a coin
Control and regulation systems
Control and regulation - definitions
Control = actions effecting a system and aimed at reaching a specific goal Regulation = control for maintaining a specific state or process
Control and regulation systems
Program and reference
Program = the set of rules used to control a system Reference = the law describing how the controlled system must behave
Control and regulation systems
Control system - definition
Cybernetic control system = one that is self-contained in its performance monitoring and correction capabilities
Control and regulation systems
Open-loop control
- execution of the control messages is not monitored
- used if noise is missing and the properties of the controlled system do not change
- forward-coupling connection = transmits control messages from controlling -> controlled subsystem
Control and regulation systems
Closed-loop control
- execution of the control messages is monitored
- used if noise is present and/or the properties of the controlled system change
- back-coupling connection = transmits data messages from controlled -> controlling subsystem
Control and regulation systems
Closed-loop control system in the body (reflex arc)
- receptors: transform the stimulus into excitation
- afferent (sensory) neurons: back-coupling channel
- neural centre: controlling subsystem
- efferent (motor) neurons: forward-coupling channel
- effectors: respond to the commands
Positive and negative feedback
Positive feedback
Positive feedback = the control results in increased divergence of the controlled system
Controlled process accelerates until the limiting constraints of the controlled subsystem are reached
