SACA Mechatronics 5 — Questions and Answers
Question 1: A technician measures excessive vibration in a rotating mechatronic assembly. Which diagnostic technique identifies the dominant frequency components causing the vibration?
- Time-domain RMS averaging
- Fast Fourier Transform (FFT) analysis (Correct answer)
- DC offset measurement
- Phase-locked loop calibration
Correct answer: Fast Fourier Transform (FFT) analysis
FFT decomposes a time-domain vibration signal into its frequency components, allowing identification of the root cause such as imbalance or misalignment.
Question 2: In a Programmable Logic Controller (PLC) scan cycle, what is the correct order of operations?
- Execute program → Read inputs → Write outputs
- Read inputs → Execute program → Write outputs (Correct answer)
- Write outputs → Read inputs → Execute program
- Execute program → Write outputs → Read inputs
Correct answer: Read inputs → Execute program → Write outputs
A standard PLC scan reads all input states first, then executes the ladder logic program, and finally writes the computed output states to output modules.
Question 3: Which sensor technology uses the piezoelectric effect to measure dynamic force or acceleration?
- Strain gauge load cell
- Piezoelectric accelerometer (Correct answer)
- Linear variable differential transformer (LVDT)
- Thermocouple
Correct answer: Piezoelectric accelerometer
Piezoelectric accelerometers generate a charge proportional to applied acceleration by exploiting the piezoelectric properties of quartz or ceramic crystals.
Question 4: In a hydraulic mechatronic system, what is the role of a servo valve?
- To filter contaminants from hydraulic fluid
- To electrically control fluid flow direction and rate to a hydraulic actuator (Correct answer)
- To store pressurized fluid for emergency use
- To measure system pressure and send feedback to the PLC
Correct answer: To electrically control fluid flow direction and rate to a hydraulic actuator
A servo valve receives an electrical command and precisely meters hydraulic fluid flow to an actuator, enabling high-force closed-loop position or force control.
Question 5: What is the purpose of a watchdog timer in an embedded mechatronic controller?
- To synchronize multiple CPUs in a multi-core system
- To reset the processor if the software fails to service it within a defined interval, preventing system lockup (Correct answer)
- To measure elapsed time for data logging
- To generate the PWM carrier frequency for motor drives
Correct answer: To reset the processor if the software fails to service it within a defined interval, preventing system lockup
A watchdog timer detects software faults by requiring periodic resets from the main program loop; if the software hangs, the timer expires and triggers a system reset.
Question 6: Which bus protocol is widely used for high-speed, real-time communication between mechatronic motion control devices such as drives and I/O modules?
- RS-232 serial
- EtherCAT (Correct answer)
- USB 2.0
- Bluetooth Classic
Correct answer: EtherCAT
EtherCAT is an industrial Ethernet protocol designed for deterministic, sub-millisecond cycle times, making it ideal for synchronized multi-axis motion control.
Question 7: In mechatronics, what does 'system integration' specifically refer to?
- Summing all actuator torques in a mechanical linkage
- The process of combining mechanical, electrical, and computational subsystems into a unified, co-designed product (Correct answer)
- Installing software updates on embedded controllers
- Calibrating individual sensors in isolation before deployment
Correct answer: The process of combining mechanical, electrical, and computational subsystems into a unified, co-designed product
System integration in mechatronics is the concurrent engineering approach that unifies mechanical, electronic, and software components so they function as an optimal whole.
SACA Mechatronics 5
A technician measures excessive vibration in a rotating mechatronic assembly.
Which diagnostic technique identifies the dominant frequency components causing the vibration?