Q24. The use of ball-screw drive is similar to: A)Harmonic drive B)Helical spur gear drive C)Worm & wheel drive D)Rack & pinion drive Q25. The pulse width modulation power amplifier controls the speed of the motor by: A)Changing the duration of each pulse B)Changing the height of each pulse C)Changing the angle of each pulse D)Changing the direction of each pulse Q26. For a two degrees step motor, what will be the number of rotations when 180 pulses are subjected to it? A) B) C)/4 D)1 Q27. The main advantage of having an open-loop control is: A)Continuous monitoring its position B)Simple in control C)Accurate positioning D)Very stable in control Q28. The position feedback in a close-loop control can be achieved by installing: A)Voltmeter B)Tachometer C)Potentiometer D)Position meter Q29. When the pulse width modulation power amplifier sends out positive pulse first and then negative pulses at equal time interval, the motor will: A)Freeze (can't be turned by hand) B)Rotate clockwise C)Rotate anti-clockwise D)De-energised (can be turned freely) Q30. Which device is NOT part of a servo-controlled system? A)Encoder B)Tachometer C)Brake D)Limit switch Q31. One of these methods is NOT used as robotic programming method: A)On-line B)Walk-through C)Off-line D)Logic Q32. An incremental encoder with 2 optical diodes has the benefit of: A)Indicating its previous position B)Indicating its speed and direction C)Encoding its position in gray scale D)Encoding its position in binary scale Q33. Which function is NOT part of the robot controller task? A)Image digitalisation B)Arm manipulation C)Logical decision making D)Sensing status Q34. Robot programming in machine language are commonly used. A)True B)False Q35. The disadvantage of using on-line programming does NOT include: A)No production run B)Being hit by moving arm C)Parallax error can occur D)Long simulation time