Practice Test GeeksCRE - Certified Robotics Engineer Practice Test
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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.

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  1. A stepper motor is specified as 1.8° per step. How many steps are required to complete one full 360° revolution?

    Answer: 200 steps

    360° ÷ 1.8°/step = 200 steps per revolution; this is the standard step count for a 1.8° stepper motor in full-step mode.

  2. What is the primary advantage of using PWM (Pulse Width Modulation) to control a DC motor's speed compared to varying supply voltage directly?

    Answer: PWM allows precise speed control with high efficiency by rapidly switching full voltage on and off

    PWM controls average power delivery by rapidly switching full supply voltage on and off at varying duty cycles, maintaining high efficiency because the switching transistor dissipates minimal power compared to linear voltage reduction.

  3. In a robotic power system, what is the purpose of an H-bridge circuit?

    Answer: Allow bidirectional control of a DC motor using four switching transistors

    An H-bridge uses four transistors arranged in an 'H' pattern; by selecting which pair conducts, current direction through the motor can be reversed, enabling forward and reverse rotation control.

  4. Which type of hydraulic pump is most commonly used in industrial robot power units due to its consistent flow rate and ability to maintain pressure against varying loads?

    Answer: Axial piston pump

    Axial piston pumps are preferred in industrial hydraulic robot systems for their high efficiency, variable displacement capability, and ability to maintain consistent high pressure against varying actuator loads.

  5. What is the function of a flyback diode (freewheeling diode) placed across a DC motor's terminals in a motor drive circuit?

    Answer: Protect the motor driver from voltage spikes caused by the motor's inductive kickback when power is cut

    When motor power is switched off, the motor's inductance causes a voltage spike (kickback); the flyback diode provides a safe current path to dissipate this energy and protect the switching transistors.

  6. In a battery-powered mobile robot, what does 'C-rating' indicate on a LiPo battery specification?

    Answer: Maximum continuous discharge current as a multiple of the battery's capacity (Ah)

    C-rating defines the maximum safe continuous discharge rate as a multiple of the battery capacity; a 5Ah battery with 20C rating can deliver up to 100A continuously (5Ah × 20C = 100A).

  7. A servo motor system uses an encoder with 4,096 counts per revolution. What is the theoretical angular resolution in degrees per count?

    Answer: 0.088°

    Angular resolution = 360° / 4,096 counts = 0.0879° per count ≈ 0.088°, meaning the system can distinguish position changes as small as 0.088°.