CRE Power Systems & Actuators

Question 1

Which type of actuator converts electrical energy into rotational motion using the interaction of magnetic fields and current-carrying conductors?

Accepted Answer

DC electric motor

Answer

Pneumatic cylinder

Answer

Hydraulic piston

Answer

Piezoelectric stack

Question 2

In a brushless DC (BLDC) motor, what component performs the commutation function that brushes handled in a brushed DC motor?

Accepted Answer

Hall effect sensors and electronic speed controller (ESC)

Answer

Slip rings and carbon contacts

Answer

Mechanical centrifugal switch

Answer

Capacitor bank and relay circuit

Question 3

A robotic joint requires 50 N·m of torque and the selected motor produces 5 N·m. What gear ratio is needed to meet the torque requirement (ignoring efficiency losses)?

Accepted Answer

10:1

Answer

5:1

Answer

20:1

Answer

50:1

Question 4

Which actuator type is most suitable for high-force, precise linear motion in a clean-room robotic assembly environment where leaks are unacceptable?

Accepted Answer

Electric linear actuator

Answer

Hydraulic cylinder

Answer

Pneumatic cylinder

Answer

Solenoid valve

Question 5

What is back-EMF (back electromotive force) in a DC motor, and what effect does it have on motor current?

Accepted Answer

A voltage generated by the spinning rotor that opposes the supply voltage, reducing current draw

Answer

A voltage that aids the supply voltage, increasing current draw

Answer

Residual charge stored in motor windings after power-off

Answer

Voltage spikes caused by brush arcing that damage motor controllers

Question 6

In a pneumatic robotic gripper system, what is the primary function of a pressure regulator?

Accepted Answer

Maintain a consistent downstream pressure regardless of supply pressure fluctuations

Answer

Convert AC to DC power for the solenoid valves

Answer

Filter particulates from the compressed air stream

Answer

Convert linear piston motion into rotational output

Question 7

Which motor parameter directly determines the no-load speed of a DC motor for a given supply voltage?

Accepted Answer

Back-EMF constant (Kv)

Answer

Winding resistance (Rw)

Answer

Torque constant (Kt)

Answer

Rotor inertia (J)