CRE Power Systems & Actuators 2

Question 1

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

Accepted Answer

200 steps

Answer

100 steps

Answer

180 steps

Answer

400 steps

Question 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?

Accepted Answer

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

Answer

PWM eliminates the need for a motor controller

Answer

PWM reduces motor inductance and eliminates back-EMF

Answer

PWM enables the motor to run in reverse without an H-bridge

Question 3

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

Accepted Answer

Allow bidirectional control of a DC motor using four switching transistors

Answer

Step up DC voltage for high-torque motor applications

Answer

Filter EMI noise from motor windings back to the power supply

Answer

Provide regenerative braking energy storage

Question 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?

Accepted Answer

Axial piston pump

Answer

Centrifugal pump

Answer

Gear pump

Answer

Peristaltic pump

Question 5

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

Accepted Answer

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

Answer

Prevent current from flowing backward through the motor

Answer

Regulate the motor's supply voltage to a safe operating level

Answer

Increase motor efficiency by recovering regenerative energy

Question 6

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

Accepted Answer

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

Answer

Cell chemistry type (C for cobalt-based cathode)

Answer

The battery's capacity in coulombs

Answer

Charging cycle count before significant capacity degradation

Question 7

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

Accepted Answer

0.088°

Answer

0.044°

Answer

0.176°

Answer

0.352°