Flashcards in Control Design, V&V, Fuzzy Logic Deck (37)
In terms of a control system what is a 'system'
Combination of components working together to perform a specific objective.
What is meant by a dynamic system
A System who's behaviour changes overtime, often i response to stimulation.
What does it mean to control a system
To regulate, direct or command the system
What is a control system
A series of components acting together to regulate or command another system.
What are some types of inpiut
Output from sensors
What is the output of a system
The actual response obtained from control system after the input has been processed, the output can be analogue or digital.
What is the difference between open and closed loop control
Closed loop control considers the output of the system through feedback
What is meant by feedback
The connection of multiple dynamic systems in such a way that they influence each other.
What is meant by controllability
Related to the possibility of forcing the system into a particular state by using an appropriate control signal, If a sate is not controllable then no signal will ever be able to control the state
What is meant to by observability
Related to the possibility of observing, through output measurements, the state of a system. If a state is not observable the controller will never be able to determine the behaviour of an unobservable state and hence cannot use it to control the system.
What is meant by stabilisable
A system is said to be stabilisable if the uncontrollable modes are stable
What is meant by analysis
The investigation of the properties of existing system, it is the best starting point but a representation of the system must exist.
What is meant by design
The choice and/ or the arrangement of a system components such that it can perform a specific task.
What are the steps in the control design process
Identifying Variables to control
Optimise and analyse
What role do sensors play in control systems
Sensors measure factors such as outputs from actuators or the system.
What are actuators in the context of a control system
These are what we can and should influence,
What is meant by a mathematical model
A series of equations or other that describes the system as closely as possible, with a good model control systems can be tested requiring no or limited access to hardware
What is meant by verification
The process of ensuring that the simulated model is an accurate representation of the physical equations that represent the dynamics of the system being modelled . Show that the simulation environment is accurate
What are the 3 steps of verification
In terms of verification what is meant by inspection
A check of each stage of the model to ensure that the system is represented correctly in each line. Each line should reflect something in the real equation. This can catch basic errors.
In terms of verification what is meant by demonstration
Model should be written so you can test elements of it as you go, for this we should input known stimulus that generate known outputs, this is done for individual elements rather than the whole system
In terms of verification what is meant by Test
A series of suitable test scenarios that you know what the output should be. These tests should be clear and have no ambiguity in the output. The tests should prove that the control system meets the requirements
What is meant by validation
The process of ensuring the simulated output response from the model is an accurate representation of output response from actual system being modelled and simulated
What needs to be decided before starting validation
Acceptable Tolerances (Response and transients)
Acceptable tracking error
Are certain outputs more important than others
What are the 2 validation methods
Analogue matching and least mean squares
Describe what is meant by Analogue matching
This is the simplest method of validation and is a comparison of the actual and simulated response. Simply a visual comparison so requires experience and expertise to be done effectively.
What is meant by the method of least mean squares
This is a quantitive measure of the accuracy of the model and is calculated using the sum of errors and provides an indication of the error over a complete test
The model parameters are then adjusted to allow the cost function to adjust.
What is meant by an intelligent controller
An intelligent controller is one that seems to make decisions based on desired output and current input to the system, it may also make decisions based on additional information
What does a fuzzy logic system aim to achieve
Attempts to mimic the way that people think in an approximate way rather than a precise way
What components would you expect to find in a fuzzy logic system
What are the rules of a fuzzy logic system
Rules are gained from verification and validation and established through tests, The rules consist of if statements
What is the role of the fuzzifier
It maps the crisp inputs into input fuzzy sets
What is the role of the interference engine
Maps input sets into output fuzzy sets
What are fuzzy sets defined by
What are the the 3 types of defuzzification
Mean Maxima Defuzzification
What are the benefits of Maximum Defuzzification
Easy to use and calculate