Why is controller tuning important and what are the typical objectives?

Controller tuning sets PID parameters (Kp, Ti, Td) for optimal performance. Objectives vary by application: Fast setpoint tracking (servo control) - quick response to setpoint changes; Disturbance rejection (regulatory) - minimize effect of load changes; Stability margin - prevent oscillation, ensure robust response. Trade-offs exist: aggressive tuning gives fast response but may oscillate; conservative tuning is stable but slow. Proper tuning reduces variability, improves product quality, enables operation closer to constraints, and reduces operator intervention.