Unit 3: Electrical and Electronics Elements - Practice Quiz

1 What type of electrical energy does a DC motor convert into mechanical energy?

2 What usually happens to the speed of a DC motor when its supply voltage is increased?

3 What is a common feature of a servo motor?

4 Which quantity is commonly controlled by a position servo motor?

5 How does a stepper motor normally move?

6 What determines the rotation of a stepper motor?

7 What component replaces mechanical brushes in a BLDC motor?

8 Which is a typical advantage of a BLDC motor?

9 What is the main purpose of a motor driver?

10 Which circuit is commonly used to control the direction of a DC motor?

11 What does an encoder commonly measure on a robot motor?

12 What kind of output can an incremental encoder produce?

13 What is the main function of a power supply system in a robot?

14 What does the voltage rating of a battery indicate?

15 What does battery capacity commonly describe?

16 What is the basic purpose of a sensor in a robot?

17 What does a proximity sensor detect?

18 What does a position sensor measure?

19 What quantity does a force sensor measure?

20 Why is signal conditioning used with sensors?

21 A DC motor is connected to a constant voltage supply, but its mechanical load suddenly increases. What is the most likely immediate response?

22 A servo motor is commanded to rotate to a target angle but stops slightly before reaching it. Which adjustment is most appropriate initially?

23 A stepper motor misses steps when accelerating a robotic joint. Which change is most likely to solve the problem?

24 Why does a BLDC motor require electronic commutation?

25 A robot must drive a DC motor forward and reverse using a microcontroller. Which circuit is normally required?

26 An incremental encoder produces 500 pulses per revolution. If a controller counts 250 pulses, what angular movement has occurred, assuming one count per pulse?

27 A robotic system contains a 24 V motor circuit and a 5 V logic circuit. What is the best power-supply arrangement?

28 A robot draws an average current of 2 A from a battery rated at 10 Ah. Ignoring losses, approximately how long can it operate?

29 A sensor produces an analog voltage that increases with temperature. Which component is most directly needed to read it with a digital controller?

30 A robot must detect metal objects without physical contact in a dusty industrial environment. Which sensor is most suitable?

31 A robotic joint must measure its absolute shaft angle immediately after power-up. Which sensor is the best choice?

32 A gripper must detect whether it is applying excessive force to a fragile object. Which sensor is most appropriate?

33 A force sensor output contains high-frequency electrical noise. Which signal-conditioning method is most appropriate before sampling?

34 A microcontroller must read a sensor every 10 ms and update a motor command at the same interval. Which feature best supports this requirement?

35 For a permanent-magnet DC motor, the back electromotive force generally increases when motor speed increases. What happens to armature current at a fixed supply voltage?

36 A servo system oscillates around its commanded position after a sudden movement. Which adjustment is commonly used to reduce this behavior?

37 A motor driver becomes very hot while operating a motor near its rated current. Which protection feature is most useful for preventing damage?

38 A quadrature encoder provides two phase-shifted signals. What additional information can this arrangement provide compared with a single-channel encoder?

39 A motor causes a controller to reset whenever it starts. Which power-system improvement is most likely to address the problem?

40 A battery pack is rated at 12 V and 4 Ah. Approximately how much energy does it store under ideal conditions?

41 A DC motor drives a constant-torque load. If the armature resistance is , the torque constant is , and the motor current is , what happens to the steady-state speed when the supply voltage is reduced while the load torque remains unchanged?

42 A position servo exhibits oscillation when commanded to hold a load with significant backlash. Which change most directly improves stability without sacrificing the servo's low-speed holding capability?

43 A stepper motor loses synchronism only during rapid acceleration, although it operates correctly at constant speed. Which redesign is most appropriate?

44 A BLDC motor produces substantial torque ripple under six-step commutation. The motor has trapezoidal back EMF, but the controller's Hall transitions are electrically misaligned. Which action is most likely to reduce the ripple?

45 A half-bridge motor driver uses complementary MOSFET PWM control. Which failure is most directly prevented by inserting dead time between turning one MOSFET off and the other on?

46 A quadrature encoder has signals and . The observed sequence is . If the controller defines this sequence as positive rotation, what is the decoded direction when the sequence reverses?

47 A robot controller requires a regulated rail at from a battery. Which supply architecture minimizes heat dissipation in the regulator while maintaining the required output?

48 A lithium battery pack is rated at , and a robot draws continuously. The battery's effective capacity at this discharge rate is only of its rating. Ignoring conversion losses, what is the most realistic operating time?

49 A robot uses an analog sensor whose output is affected by both supply variation and ambient temperature. Which design best separates actual measured changes from these systematic disturbances?

50 An inductive proximity sensor reliably detects steel but fails to detect an aluminum target at the same distance. Which explanation is most accurate?

51 A potentiometric joint sensor becomes noisy near one end of its mechanical travel because the wiper approaches the resistive track boundary. Which change most directly improves measurement reliability?

52 A strain-gauge load cell is connected as a Wheatstone bridge. The measured output changes significantly when the cable temperature changes, even though the applied force is constant. Which remedy is most appropriate?

53 A sensor signal contains useful frequencies up to and interference near . The ADC samples at . Which conditioning strategy is technically necessary?

54 A motor-control task must execute every , but a communication routine occasionally blocks for . Which architecture best preserves deterministic motor timing?

55 A DC motor's armature current is controlled by PWM. At low duty cycles, the motor produces uneven motion because current falls to zero during part of each PWM period. Which modification most directly addresses this condition?

56 A servo uses an incremental encoder and is powered on after its joint has been moved manually. The controller must establish an absolute joint reference before motion. Which method is required?

57 A stepper motor is operated with microstepping, but the load requires accurate absolute positioning after power is removed. Which statement is correct?

58 A sensorless BLDC controller fails to start reliably from rest but runs correctly once spinning. Which design change addresses the fundamental startup problem?

59 A motor driver is rated for continuous current but repeatedly overheats when delivering RMS with a high peak-current waveform. Which factor best explains the overheating?

60 An incremental encoder produces 1024 pulses per revolution on channel A, and the controller decodes both edges of both channels. What nominal count resolution is obtained per revolution?