Long-form guides on PID tuning, FOPDT identification, temperature and flow loops, anti-windup, gain and phase margin, and choosing between P, PI, PD and PID.
How PID loops behave on ovens, tanks, flow valves, DC motors, HVAC and pressure vessels — and how to tune each class of process.
Read articleHow to simulate a PID loop with first-order, FOPDT and second-order plants, and how to read rise time, overshoot, settling time, IAE, ISE and ITAE.
A practical comparison of classical PID tuning rules, FOPDT identification, and when to trust each formula versus numerical optimisation.
How proportional, integral and derivative control work, why industrial loops use PID, and how to choose Kp, Ki and Kd without guessing.
A pragmatic workflow for tuning a PID loop — from identifying the process model to picking a robust rule and verifying the result.
Run reaction-curve and ultimate-cycle Ziegler–Nichols tests, compute Kp, Ti and Td from K, τ, L or Ku, Pu, and know when the rule is too aggressive.
Cohen–Coon PI and PID formulas for FOPDT loops with L ≳ τ, a numeric L/τ ≈ 1.2 example, overshoot, robustness limits, and when IMC or SIMC is safer.
Why a saturated actuator makes an integral controller overshoot badly — and how back-calculation fixes it.
Internal model control and Lambda tuning for FOPDT plants: choosing λ, PI and half-rule PID formulas, robustness versus speed, SIMC, and a numeric example.
Design a bump test, wait for steady state, and extract FOPDT gain K, time constant τ and dead time L with tangent, 28/63 % and two-point methods.
A plain-language introduction to the two frequency-domain numbers that tell you how close a control loop is to instability.
Tune oven, heater and exchanger PID loops: thermal lag, transport dead time, filtered derivative, anti-windup and an IMC/SIMC worked example.
PI-first practices for noisy industrial flow loops: valve characteristics, stiction, cascade slaves, PV filters and a worked FOPDT example.
A quick decision guide for choosing a controller structure based on your process and requirements.
Tune tank level as an integrating process: why FOPDT rules fail, averaging versus tight level, SIMC and Tyreus–Luyben, and overflow risk.
Stop derivative kick on setpoint steps: derivative-on-measurement, setpoint weighting, Td/N filtering, and when to switch D off.
Positional vs velocity PID, Euler vs Tustin, Ts rules of thumb, aliasing, bumpless transfer and discrete anti-windup for real PLCs.
Open-loop L(jω), gain and phase crossover, what P, I and D do to Bode plots, Nyquist encirclements, and why phase margin predicts overshoot.
Practical knobs for less overshoot and faster settle: Kp, Ti, filtered Kd, setpoint weighting, IMC λ, anti-windup, and optimiser objectives.
Definitions of IAE, ISE, ITAE and ITSE, trapezoidal integration, why ISE is aggressive, and how Nelder–Mead searches Kp Ki Kd without lying.
How a relay limit cycle measures Ku and Pu, converts to Ziegler–Nichols or Tyreus–Luyben PID, and when hysteresis, noise or safety rule the test out.
Why a fast inner flow, speed or current loop protects the outer temperature, level or composition loop — and when cascade control falls apart.
Feedback waits for error; feedforward uses a measured disturbance. Static and lead-lag FF, PID plus FF, and how to test the combination in simulation.
Skogestad SIMC and Åström AMIGO as robust PID rules: half-rule, τc, integrating plants, and a numeric FOPDT comparison with Ziegler–Nichols and Cohen–Coon.