80 Questions
Which type of system does not correct for disturbances and is simply commanded by the input?
Open-loop system
What is the controlled variable (output) of a toaster?
Color of the toast
What is the advantage of closed-loop systems over open-loop systems?
Greater accuracy
What is the process by which a system's performance is determined?
Analysis
Which of the following is an example of an automatically controlled system mentioned in the text?
A self-guided vehicle in an aerospace assembly plant
What is the purpose of a control system?
To obtain a desired output with desired performance
Which of the following is NOT an example of a control system mentioned in the text?
A moving object being tracked by the eyes
What does the model mentioned in the text predict?
The time required for the grade to rise
Which of the following is a major objective of systems analysis and design discussed in the text?
Achieving stability
What is the importance of transient response in a control system?
It affects the comfort of the system's users
What is the steady-state response of a system?
The response that resembles the input and remains after the transients have decayed to zero
What happens if a control system does not have stability?
The system's natural response grows without bound
Which of the following is true about the transient response of an unstable system?
The transient response grows without bound and without any evidence of a steady-state response.
What is the main objective of control system analysis and design?
To design systems that are stable.
What are some important considerations in control system design?
Factors affecting hardware selection, such as motor sizing and choice of sensors.
Why does the engineer want to create a robust design?
To ensure that the system will not be sensitive to parameter changes.
Which two major measures of performance are apparent in the elevator system described in the text?
Transient response and steady-state error
What are the four primary reasons for building control systems according to the text?
Power amplification, remote control, convenience of input form, and compensation for disturbances
What is the distinguishing characteristic of an open-loop system according to the text?
It cannot compensate for any disturbances that add to the controller's driving signal
What is the purpose of an input transducer in a control system according to the text?
It converts the form of the input to that used by the controller
Which of the following is an advantage of control systems mentioned in the text?
All of the above
What are the two major measures of performance in the elevator system described in the text?
Transient response and steady-state error
Which of the following is an example of a control system mentioned in the text?
All of the above
What is the distinguishing characteristic of an open-loop system according to the text?
It cannot correct for disturbances
What is the purpose of an input transducer in a control system according to the text?
To convert the form of the input to that used by the controller
Why are control systems useful in remote or dangerous locations according to the text?
To compensate for disturbances
Which of the following is NOT an example of an automatically controlled system mentioned in the text?
A student's study time and grade model
What is the purpose of a control system?
To obtain a desired output with desired performance
What is the distinguishing characteristic of a closed-loop system according to the text?
It continuously compares the actual output to the desired output
What is the main objective of control system analysis and design?
To obtain a desired output with desired performance
What are some important considerations in control system design?
Stability, robustness, and desired performance
Which of the following is true about the transient response of a stable system?
It decays over time and reaches a steady-state
Which of the following is a major objective of control system analysis and design discussed in the text?
All of the above
What is the purpose of an input transducer in a control system according to the text?
To convert physical input into an electrical signal
What is the significance of the natural response in a control system?
It describes the way the system dissipates or acquires energy
Which of the following is true about the transient response of an unstable system?
It grows without bound
What is the consequence of a control system not having stability?
The system will be uncontrollable and potentially self-destructive
What is the primary concern regarding the steady-state response in a control system?
The accuracy of the steady-state response
Which of the following is a disadvantage of open-loop systems mentioned in the text?
Open-loop systems do not correct for disturbances.
Which of the following is true about closed-loop systems mentioned in the text?
Closed-loop systems correct for disturbances.
What is the purpose of an output transducer in a control system according to the text?
To measure the output response and convert it into the form used by the controller.
What is the result of the first summing junction in a closed-loop system according to the text?
The input signal is subtracted from the output signal.
What is the actuating signal called in closed-loop systems according to the text?
Error
What is the main advantage of closed-loop systems over open-loop systems according to the text?
Closed-loop systems have greater accuracy than open-loop systems.
Which of the following is NOT a consideration in control system design, according to the text?
Stability
What is the purpose of a robust design in control systems, according to the text?
To make the system consistent with the design
Which of the following statements about parameter changes in control systems is true, according to the text?
Parameter changes can lead to small or large changes in system performance
What is the main characteristic of an unstable system, according to the text?
Transient response grows without bound
What is the relationship between the transient response and the natural response of a system, according to the text?
The transient response is directly related to the natural response
What is the purpose of stability in control system design, according to the text?
To ensure the transient response decays to zero
What is the power transmission medium in hydraulic systems?
Pressurized hydraulic fluid
What are electrohydraulic (EH) systems controlled by?
Electrical means
What are hydro-mechanical systems controlled by?
A combination of mechanical and hydraulic mechanisms
What component controls the flow of pressurized fluid in an electrohydraulic system?
Main valve
What connects the operator input devices to sensors in electronically controlled hydraulic systems?
Integrated sensors
What is the purpose of accumulators in hydraulic systems?
Store pressurized fluid
What are the three most important specifications for a hydraulic filter?
Minimum size of the particles it can filter, maximum pressure it can withstand, and maximum flow rate it can support
In a hydraulic system where the source of power is a fixed displacement gear type pump, how is the flow to the cylinder controlled?
By a manually actuated valve
In a multi-function hydraulic power-based motion system, how are the hydraulic valve-actuator pairs connected to the pump and tank lines?
In parallel
In a hydraulic circuit for the motion of a cylinder of an excavator, what is the power source?
An internal combustion engine
In a multi-function hydraulic power-based motion system, what type of connection may be used when it is not practical to provide a large enough pump to support the full load of each circuit?
Series connections
In a hydraulic circuit for the motion of a rotary hydraulic motor for a service truck, how is the speed of the hydraulic motor controlled?
Through a closed-loop control system
What is the primary purpose of proportional flow control valves in hydraulic systems?
To regulate fluid flow in terms of rate, direction, and pressure
What is the main function of the hydraulic reservoir in a hydraulic power supply unit?
To store a volumetric size 3 to 5 times the flow rate of the pump
What is the crucial function of the hydraulic pump in hydraulic power transmission?
To convert mechanical power into pressurized fluid
In industrial applications, what is commonly used to power the hydraulic pump?
Electric motors
What are the two major designs of hydraulic power unit mentioned in the text?
JIC style and overhead design
What type of actuators can be found in hydraulic motion systems?
Linear cylinders or rotary hydraulic motors
What is the purpose of safety relief valves in hydraulic circuits?
To protect against excessive pressures
What is the main function of ON/OFF valves in hydraulic systems?
Turn controlled flow on or off
What is the role of accumulators in hydraulic motion control systems?
Serve as pressurized fluid storage components
What type of gas is used in hydro-pneumatic accumulators?
Dry nitrogen
What is the purpose of filtration in hydraulic systems?
Remove solid particles from hydraulic fluid
What is the advantage of using ON/OFF valves in parallel for finite speed or force control?
Lower cost and simpler design
What is the purpose of identifying sensors in hydraulic circuit diagrams?
To understand the control decisions and logic used in the circuit
What is involved in the design of an electro-hydraulic motion control system?
Component sizing and selection
What are the measured variables in an electro-hydraulic system for control purposes?
Spool displacement and flow rate
What is the primary concern in the design of electro-hydraulic motion control systems?
Selecting the appropriate components
Why is it important to identify the main power supply and actuators in hydraulic circuit diagrams?
To ensure the safety of the power flow paths in the circuit
What is the significance of flow control valves in hydraulic circuit diagrams?
To identify the power flow paths in the circuit
Study Notes
Interpreting Hydraulic Circuit Diagrams
- Hydraulic circuit diagrams show connections between hydraulic, mechanical, and electrical components using lines and standard symbols.
- It takes multiple days to fully understand a given hydraulic circuit.
- Guidelines for interpreting hydraulic circuit diagrams include identifying the main power supply and actuators, flow control valves, safety valves, power flow paths, pilot control circuits, and operator command signal sources.
- It is important to identify sensors and the logic used in control decisions, as well as any built-in priority and over-ride type logic in the circuit.
- The design of an electro-hydraulic motion control system involves specifying requirements, system concept design, component sizing and selection, control algorithm design, modeling and simulation, and hardware testing.
- Measured variables in an electro-hydraulic system for control purposes include load position and speed, load pressure, load force or torque, spool displacement, flow rate, pump output pressure, pump displacement, and pump speed.
Test your knowledge on open-loop systems and their characteristics with this quiz. Learn about how open-loop systems are controlled by input without correcting for disturbances. Find out how toasters are a prime example of open-loop systems and their controlled variables. Challenge yourself with questions on the topic and expand your understanding of system control.
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