Concept: True Robust Control

What Is Being Redefined

Conventional H∞ robust control treats robustness as a static design result: a controller is synthesized once to satisfy a worst-case bound.

True Robust Control redefines robustness as an operational capability: the ability to observe, interpret, and act on uncertainty during operation.

Key Redefinition

Robustness is not the absence of failure.
It is the ability to respond before guarantees collapse.

This implies:

• Robustness is dynamic
• Robustness has states
• Robustness requires decision-making

Why Classical Robust Control Is Insufficient

• Worst-case assumptions are overly conservative
• Real degradation is gradual, not instantaneous
• Different uncertainties matter at different frequencies

Static robustness wastes performance when systems are healthy
and reacts too late when degradation accelerates.

Core Principles

1. Uncertainty is observable
   Δ is monitored, not assumed.

2. Meaning matters
   Low-frequency, high-frequency, and input-side uncertainties imply different risks.

3. Act before breakdown
   Design adaptation is triggered before ∥Δ∥∞ reaches 1.0.

4. Minimal intervention
   Only the necessary design elements are adjusted.

Position in Control Engineering

This concept does not replace:

• H∞ theory
• Robust stability analysis

It complements them by addressing how robustness is actually operated in real systems.