What is automation?
Transforming a mechanism, device, machine, facility or process to make it automatic.
What is the goal of a programmable logic controller (PLC)?
Bring added value to a set of raw materials to produce products of higher value.
What human intervention do PLC’s need (4)?
- machine monitoring
- loading, unloading and inspecting machines
- participation in the production process
- adjustment and maintenance
What do PLC’s gain from automation(4)?
- reduced labor cost and material savings
- reducing hazardous work and safety increase
- improved product quality and performance
- higher productivity and quality job creation
What is hardware?
Implementing physical decides to achieve the desired logic/operation.
What is a pro and con of hardware?
Pro: reliability
Con: non flexible for future changes
What is software?
Using programming to achieve desired logic /operation.
What is a pro and con of software?
pro: flexible to future changing
con: not used for important safety functions
What is the single proven technology protection method(3)?
- position switched or forced open contacts
- manually check for periodic safety functions.
- oversizing some components
What is the single with supervision protection method(2)?
- similar to single proven technology protection, but also has self monitoring features.
- failure detecting circuits made with contactors and relays
What is the redundant protection method(4)?
- duplicating critical components or functions
- using different technologies
- combining the normally open and normally closed contact interlocks
- combining different, electrical and non-electrical systems.
What is the redundant with supervision protection method(1)?
same as the redundant protection method but adds a continuous supervision function
What is ladder logic?
was used before PLC’s to describe automation technology made by using electromagnetic relays
What is the difference between a static and dynamic system?
static systems do not change with time while dynamic systems do change with time.
What makes a good model(6)?
- clearly defined questions
- clearly stated assumptions
- adaptable
- reproducible( clearly defined variables)
- use the best data available
- interpret results with caution
What are the 6 steps of the design approach?
- define the system and its components
- make a mathematical model with its assumptions
- make differential equations describing the model
- solve equations for desired output variables
- examine solutions and assumptions.
- if needed, reanalyze or redesign the system
What is a control system?
an interconnection of components forming a system that will provide a desired system response.
What is the difference between an open and closed loop control system?
Closed-loop: uses a measurement of the output signal and a comparison with the desired output to generate an error signal that is used by the controller to adjust the actuator.
Open-loop: directly generates the output in response to an input signal.
What are the advantages of closed-loop feedback control systems(5)?
- decreased sensitivity of variations in parameters
- rejects disturbances
- attenuate the measurement noise
- reduce the steady-state error
- easy control and adjustment of the transient response of the system.
What is a linear system?
A system that satisfies the properties of superposition and homogeneity.
What are the superposition principle?
for all linear systems, the net response caused by two or more stimuli is the sum of the response that would have been caused by each stimulus individually.
What is the homogeneity principle?
the output of a linear system is always directly proportional to the input, so if we put in twice as much into the system we should get twice as much back,
What is linear approximation?
is as accurate as the assumption of small signals is applicable to a specific problem.
What are the 3 test input signals?
- step input
- ramp input (integral of the step input)
- parabolic input (integral of the ramp input)
