Explain open loop and closed loop control systems with examples and state their merits and demerits?

flowchart TD
    A[Open Loop] -->|No feedback| B[Fixed schedule action]
    C[Closed Loop] -->|Measures output| D[Compare to set point]
    D --> E[Form error]
    E --> F[Adjust final control element]

• Open loop: acts on fixed schedule without checking result; no feedback
• Closed loop: measures controlled variable, compares to set point, forms error, adjusts final control element
• Shipboard open-loop example: starting air system (fixed timing), mechanical fuel injection timing
• Shipboard closed-loop example: jacket water temperature control, boiler water level control
• Open-loop merits: simple design, stable, low cost
• Open-loop demerits: inaccurate, no correction for disturbances
• Closed-loop merits: accurate, self-correcting, handles disturbances
• Closed-loop demerits: complex, potential instability, higher cost