Control System Notes Gate 2026

C(caps)ontrol Systems is one of the most important subjects in GATE for ECE and EE aspirants. It deals with the analysis and design of systems to regulate their behavior using feedback principles. A strong foundation in this subject helps in solving complex problems related to stability, time response, frequency response, and compensator design. These notes are carefully prepared to cover the entire GATE 2026 syllabus with clear explanations, solved examples, and shortcuts to boost your preparation.

Control System Notes Gate 2026 

(toc)Table of Content

1. Introduction to Control Systems

• Definition of Control System
• Open-Loop vs Closed-Loop Systems
• Examples from real life (fan regulator, cruise control, etc.)
• Advantages of Feedback

 

2. Mathematical Modelling of Systems

• Transfer Function
• Differential Equations & Laplace Transform approach
• Block Diagrams
• Block diagram reduction rules
• Signal flow graphs (Mason’s gain formula)
• Mechanical & Electrical system modelling

 

3. Time Domain Analysis

• Standard test signals (Step, Ramp, Parabolic, Impulse)
• Transient response analysis
• Rise time, Settling time, Overshoot, Delay time
• Steady State Error (SSE)
• Error constants (Kp, Kv, Ka)
• Stability in Time Domain
• First-order system response
• Second-order system response

4. Stability Analysis

• Concept of Stability
• Routh–Hurwitz Criterion
• Root Locus
• Rules of construction
• Angle & magnitude conditions
• Breakaway & break-in points
• Asymptotes & centroid

5. Frequency Domain Analysis

• Frequency response basics
• Bode Plots
• Construction rules
• Gain margin & Phase margin
• Polar Plot
• Nyquist Plot
• Nyquist stability criterion
• Nichols Chart

6. Compensators & Controllers

• Proportional (P) Controller
• Integral (I) Controller
• Derivative (D) Controller
• PI, PD, and PID Controllers
• Lead, Lag, and Lead–Lag Compensators

7. State Space Analysis

• State variables & state equations
• Representation of systems in State Space
• Conversion from transfer function to state space
• Solution of state equations
• Controllability & Observability. 

Download Notes 

• For Handwritten Notes 👉👉 CLICK HERE

Reference Text Books 

1. Control Systems Engineering - Norman S.NISE 👉 CLICK HERE 
2. Control Systems Engineering - L.J Nagrath, M.Gopal 👉 CLICK HERE 
3. Automatic Control Systems - Kuo Benjamin C.   👉 CLICK HERE 

Conclusion 

Control Systems is a scoring and concept-driven subject in GATE. With a clear understanding of fundamentals, regular practice of PYQs, and revision of formulas, you can master both theory and problem-solving. Use these notes as a structured guide to strengthen your preparation and gain confidence for GATE 2026.