Match functional blocks in a classical servo control system to representative hardware. List I (Functional component) List II (Device example) A. Error detector 1. Three-phase fractional-horsepower induction motor (FHP IM) B. Servo motor 2. Synchro transmitter and control transformer C. Amplifier 3. Tacho generator (feedback signal) D. Feedback element 4. Armature-controlled FHP DC motor 5. Amplidyne (power amplifier)
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AA-2, B-4, C-1, D-5
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BA-4, B-2, C-5, D-3
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CA-2, B-4, C-5, D-3
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DA-1, B-2, C-3, D-5
Answer
Correct Answer: A-2, B-4, C-5, D-3
Explanation
Introduction / Context:Classical servo systems comprise an error detector, a power amplifier, a servo motor, and a feedback element. Recognizing typical hardware that implements each block is crucial in control systems and mechatronics.
Given Data / Assumptions:
- Error detector compares reference and feedback signals.
- Servo motor converts the amplified control signal into mechanical motion.
- Amplifier raises signal power to drive the motor.
- Feedback element measures speed or position to close the loop.
Concept / Approach:
Synchros (transmitter and control transformer) form a classic error detector by producing a voltage proportional to angular difference. An armature-controlled FHP DC motor is a canonical servo motor due to easy speed control. Amplidynes (rotating amplifiers) historically served as powerful control amplifiers. A tacho generator delivers a voltage proportional to speed for feedback.
Step-by-Step Solution:
Error detector → synchro pair ⇒ A-2.Servo motor → armature-controlled DC motor ⇒ B-4.Amplifier → amplidyne ⇒ C-5.Feedback element → tacho generator ⇒ D-3.Verification / Alternative check:
Control textbooks show synchro error detectors in position-control servos; DC servomotors are used for precise control; amplidynes provided high power gain before solid-state drives; tachogenerators remain common for speed feedback.
Why Other Options Are Wrong:
- Mapping the amplifier to an induction motor misunderstands block roles.
- Using a three-phase induction motor as the standard servo motor complicates control; DC servomotors are the classical choice for fine control.
Common Pitfalls:
Confusing sensors (tacho) with error detectors (synchros); the former measures speed directly, while the latter measures difference between commanded and actual positions.
Final Answer:
A-2, B-4, C-5, D-3