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Dynamical system
systems where the effect of a certain action only becomes visable, or reaches a steady state, after some time
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Model
Simplified dicription of a system, just complex enough to describe or study the phenomena that are relevant for our problem contect
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Control system
System with a feedback loop to keep certain quantities constant (e.g. temperature of thermostat in house)
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Elementary system
System>subsystem>sub(sub)system>sub(subsub)system>
>elementary system
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Bileteral interaction
System where the action of one subsystem leads to a reaction of the other subsystem
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a-causal model
Same relations as causal relation diagram but without choosing what we consider as cause and effect
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Positive feedback
Leads to exponential growth
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Discrete systems
Systems that are described at fixed, discrete, time intervals
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Continuous-time systems (question 3 on practice exam)
System with an input signal and feedback. A typical property is the memory function. This memory determines the state of the system (the amount of something at a certain moment, e.g. water in a tank) In a continuous time system the memory in an integrator. The output value of an integrator can be used as a state variable.
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Transient responses or transients
Graphs which show how a system goes from equilibrium state to another
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Capacitor
- Can be seen as battery, stores electrical energy
- q = it
- q = charge of battery, i = constant
- If i is not constant:

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Inductor
Coil of wire, stores energy in the form of a magnetic field
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Inductance
Property that belongs to a coil.
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Magnetic flux
the magnetic flux through a surface is the component of the magnetic field passing through that surface
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Flux linkage
When the coil has n windings the so-called flux linkage is equal to the product of the number of windings and the magnetic flux. Capacitor stores electrical energy in the form of electrical charge, an inductor, in the form of coil, in the form of flux linkage.
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Transfer function
A mathematical representation of the relation between the input and output of a linear time-invariant system with zero initial conditions and zero-point equilibrium.
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Water hammer
Can be observed when water is flowing through a pipe and the flow at the end of the pipe is cut off.
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Elementary physical models
Elementary subsystem of a component
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Ideal Physical Model (IPM)
Model solely built of elementary physical models (basically a 20-sim model)
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Lumped paramaeter
model Dominant physical behavior of a model represented by a limited number of interconnected ideal physical elements
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Static equilibrium
Gravity firce will be compensated by the force of a spring
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Moment of inertia
= mass moment of inertia = angular mass
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Transfer function
Function with delay operator
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Gyrator
Used as a transducer between different physical domains.
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Ideal voltage source
- Element that delivers constant voltage
- Must have an internal resistance of zero
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Modulated voltage source
Modulated by sinusoidal signal.
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Ideal current source
- Element that delivers constant current
- Must have a large internal resistance
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Node
Point where two or more elements are connected
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Path
Formed by a number of interconnected circuit elements
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Transducer
Element that couples multiple domains (a.g. electrical en mechanical e.g. electric engine)
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Sensor
- Transducer that is able to convert physical quantities
- extract information from the system in the form of a digital signal
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Actuator
Converts signals into physical quantities (modulated volatage source)
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Power conjugated variables
Variables with the dimension of power in watts
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One-port element
Elements for which there is a single variable which determines the flow of energy to and from this element
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Two-port element
Elements that change the ratio between u and I of F and v, but the product P remains constant
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Bonds
Half arrows, presents energy flow
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1-junction
- Neutral symbol 1 which replaces the domain-dependent variables I and v
- Represents heat flows
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0-junction
Represents temperatures
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Bilateral signal flow
Represented by a bond that combines two signals
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Actuator
Element that converts signals to power (e.g. modulated voltage source)
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Commutation
The process of inverting the direction of the current
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Counter electromotive force
Voltage that is proportional to the angular velocity
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Tachogenerator
Sensor to measure angular velocity
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Component
Consists of physical elements, which under certain circumstances may be left out of the model
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Rectification
The process of converting elements from AC to DC
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Diode
Suppresses the negative parts of the sine wave
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Diode bridge
Converts the negative parts of the sine waves to positive ones
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Double-sides rectification or full-wave rectification
Extra diodes that ensure that both parts of the sinusoidal signal contribute to charging the capacitor
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Feed-forward control
Real condition at the end of a process has no influence on the actual duration of the process
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Fuzzy controller
Observation with no real values (a bit longer, much shorter,
)
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Proportional gain
Depends on another variable (like approaching a red traffic light, the distance varies)
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Overshoot
Proportional gain doesnt work (driver brakes too late and crosses the stopping line)
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Derivative control
Another variable is needed because there was an overshoot. This will be velocity. Velocity is derived from the position
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Control engineering
The art of tuning the parameters of a controller
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Unstable system
oscillations increase or exponential growth
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Op-amp
Operational amplifier
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Active component
Component with external power supply
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Non-inverting input
Positive input of an amplifier
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Inverting input
Negative input of an amplifier
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Adder circuit
Circuit which can make the weighted sum of two or more input signals
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Passive circuit
Circuit with only resistor, capacitors and inductances
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Low-pass filter
Filter that passes low frequencies
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Pneumatic controllers
Controller which uses compressed air to carry a signal
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Hydraulic systems
Used when high forces are needed
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Soft real time performance
Performance is fast enough
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Hard real time performance
Performance is fast enough and at fixed time intervals
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Embedded computer
Computers you dont see (implemented in microwaves etc), fitted with embedded control systems
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Digital control systems
Embedded control systems
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Ad-converter
Analog to digital converter
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Hold circuit
Equipped in DA-converter. Circuit that holds the voltage until a new conversion is performed
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Zero-order hold
Hold circuit where the voltage is kept at a constant value
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Sampling rate
T,sample = t,dominant/10
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Aliasing
Happens when sampled with a too low sampling frequency. The frequency of the sine wave will change
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Nyquist rate
2* the highest frequency
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Hookes law
- Relation between the force F acting on a spring and the deformation of the spring, the change in length x:
- F = kx
- k = the spring constant
- also correct:
- x=1/k*F or x=cF
- c = 1/k = the compliance
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Newtons law
- F = ma
- a = (1/m)* F
- F = ma = m(d(v)/dt)
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Kirchoffs law
- Sum of all currents = 0
- Sum of all voltages = 0
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dAlemberts law
The algebraic sum of all forces acting on an object in a mechanical system and the time derivative of the impulse of the object equals zero.
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