Power Systems & Actuators Flashcards
7 cards from real CRE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Power Systems & Actuators flashcards as text
Which type of actuator converts electrical energy into rotational motion using the interaction of magnetic fields and current-carrying conductors?
Answer: DC electric motor
A DC electric motor converts electrical energy into rotational mechanical motion through electromagnetic force between the stator's magnetic field and the rotor's current-carrying windings.
In a brushless DC (BLDC) motor, what component performs the commutation function that brushes handled in a brushed DC motor?
Answer: Hall effect sensors and electronic speed controller (ESC)
In a BLDC motor, Hall effect sensors detect rotor position and feed data to an ESC, which electronically switches current to the appropriate stator windings for commutation.
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)?
Answer: 10:1
Gear ratio = required torque / motor torque = 50 N·m / 5 N·m = 10:1, meaning the gearbox multiplies torque tenfold while reducing output speed proportionally.
Which actuator type is most suitable for high-force, precise linear motion in a clean-room robotic assembly environment where leaks are unacceptable?
Answer: Electric linear actuator
Electric linear actuators are ideal for clean-room environments because they produce no fluid leaks, offer precise position control, and require no compressors or hydraulic power units.
What is back-EMF (back electromotive force) in a DC motor, and what effect does it have on motor current?
Answer: A voltage generated by the spinning rotor that opposes the supply voltage, reducing current draw
Back-EMF is generated by the rotating rotor acting as a generator; it opposes the supply voltage and reduces current draw, limiting speed and providing a natural speed-regulation mechanism.
In a pneumatic robotic gripper system, what is the primary function of a pressure regulator?
Answer: Maintain a consistent downstream pressure regardless of supply pressure fluctuations
A pressure regulator maintains a set downstream pressure by continuously adjusting an internal valve, ensuring gripper force remains consistent despite fluctuations in the supply air pressure.
Which motor parameter directly determines the no-load speed of a DC motor for a given supply voltage?
Answer: Back-EMF constant (Kv)
The back-EMF constant (Kv), expressed in RPM/V, directly relates supply voltage to no-load speed; at no load, back-EMF approaches supply voltage and speed ≈ Kv × Vsupply.