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Define control system and closed loop block roles

Short answer

A control system regulates output to a desired value. In a closed-loop system, the reference input sets the target; the error detector compares it with feedback; the controller generates a control signal; the actuator drives the plant; the sensor measures output for feedback; disturbances are unwanted inputs.

Define control system. Draw the block diagram of closed loop control system and explain the role of each block briefly.

A control system is an arrangement of physical components connected so as to regulate or direct a system to obtain a desired output.

                       disturbance d
                            |
 r   +----+  e   +------+ u +---+---+   c
---->| Σ  |----->|Contr-|-->| Plant |----+---->
     +----+      | oller|   +-------+    |
      - ^        +------+                |
        |  b    +-----------------+      |
        +-------| Feedback/sensor |<-----+
                +-----------------+

Role of each block

  1. Reference input rr (set point): desired value of the output.
  2. Error detector / summing point: compares rr with feedback bb and gives error e=r−be = r - b.
  3. Controller: acts on the error (P, PI, PID) and produces control signal uu.
  4. Actuator: power element (motor, valve, amplifier) that applies uu to the plant.
  5. Plant / process: the system being controlled; gives the controlled output cc.
  6. Disturbance dd: unwanted input acting on the plant (load change, noise).
  7. Feedback element / sensor: measures cc and converts it to bb, comparable with rr.

Overall: C(s)R(s)=G(s)1+G(s)H(s)\dfrac{C(s)}{R(s)} = \dfrac{G(s)}{1+G(s)H(s)}.

✓ Answer checked by Claude Opus 5.5 (high effort)

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