🛠 Design Recovery Control

---

📌 Overview

Design Recovery Control (DRC) is a control architecture that addresses system degradation
by recovering violated control design assumptions,
rather than directly manipulating control inputs or physical systems.

DRC explicitly separates the following layers:

• ⏱ Real-time control — PID
• 🔄 State and safety supervision — FSM
• 🧠 Design recovery and reconfiguration — LLM

The fundamental premise of DRC is:

Large Language Models must not replace controllers.
They operate strictly as design supervisors when original control assumptions no longer hold.

---

🎯 Motivation

Conventional control frameworks focus primarily on:

• 🛡 Reliability Control
  → Preventing degradation by reducing physical stress (V–I, temperature, duty cycle)

• 🔁 Recovery Control
  → Restoring output or function via reset, recalibration, or fallback logic

However, many real-world failures occur because:

The original control design assumptions drift or collapse over time,
even when the system remains operational.

➡️ Design Recovery Control explicitly targets this gap.

---

🧠 Core Concept

🧩 Layered Control Structure

┌──────────────────────────┐
│ LLM : Design Supervisor  │  ← Design Recovery Control
├──────────────────────────┤
│ FSM : State Management   │
├──────────────────────────┤
│ PID : Real-Time Control  │
├──────────────────────────┤
│ Plant / Physical System  │
└──────────────────────────┘

🔍 What Is Recovered — and What Is Not

DRC does NOT recover:

• ❌ Control outputs
• ❌ Control inputs
• ❌ Physical degradation itself

DRC DOES recover:

• ✅ Control design assumptions, including:
  • PID gain validity
  • FSM transition conditions
  • Operating mode definitions

---

📐 Scope of Design Recovery

The LLM is permitted to modify design-level artifacts only, including:

• 🧮 PID gain sets (Kp, Ki, Kd) within predefined bounds
• 🔄 FSM transition conditions and thresholds
• 🗺 Operating mode definitions and annotations

The LLM is explicitly prohibited from:

• 🚫 Injecting or modifying control signals
• 🚫 Accessing real-time control loops
• 🚫 Altering execution timing or scheduling
• 🚫 Bypassing FSM safety guards
• 🚫 Performing continuous or autonomous online control

All LLM-generated changes must be explicit, inspectable, and reversible,
and may require human or system-level approval before deployment.

---

📜 Design Principles

1. 🔒 LLM never touches real-time control inputs
2. 🛡 Safety and stability are enforced exclusively by PID and FSM
3. ⏳ LLM operates asynchronously and discontinuously
4. 🔍 All design updates are explicit, inspectable, and reversible
5. 👤 Human or system-level approval may gate design changes

---

🔗 Relation to AITL

• 🧠 AITL (Adaptive Intelligent Technology Loop)
  → An architectural pattern for layered intelligent control systems

• 🛠 Design Recovery Control
  → A domain-independent control engineering concept
  defining the role and boundaries of the design supervision layer

This repository formalizes the design recovery layer
used within AITL-based systems,
without binding it to any specific application domain.

---

🛠 Typical Use Cases

• ⏳ Control systems with long-term parameter drift
• 🧱 Degraded physical systems (thermal, mechanical, semiconductor, MEMS)
• 🚨 Safety-critical systems where LLM real-time control is unacceptable
• 👥 Human-in-the-loop or audit-required control redesign workflows

---

🚫 What This Repository Is NOT

• ❌ An end-to-end LLM controller
• ❌ A reinforcement learning controller
• ❌ A reliability or lifetime optimization framework

---

📦 Repository Scope

This repository focuses on:

• 📘 Concept definition
• 🧩 Architectural clarification
• 📐 Boundary and responsibility specification
• 🧪 Minimal, illustrative PoC references (non-real-time)

Domain-specific implementations
(inkjet, MEMS, semiconductor, robotics, etc.)
are intentionally handled in separate repositories.

---

📚 Documentation

• 📘 Design Variables
• 🔄 Design Recovery Workflow
• ⚠ Failure Modes
• 📊 Comparison: DRC vs RL vs LLM Control
• ❓ FAQ
• 🧾 Audit Checklist
• 🧠 LLM Prompt Template

---

🧪 Proof of Concept (PoC)

• 🧩 Minimal Design Proposal PoC (Python)

---

🔒 Design Intent Freeze

This document fixes the conceptual definition of Design Recovery Control.

Future work may extend implementations or examples,
but must not redefine the core assumptions, boundaries, or prohibitions described here.

---

Author

📌 Item	Details
Name	Shinichi Samizo
Expertise	Semiconductor devices (logic, memory, high-voltage mixed-signal) Thin-film piezo actuators for inkjet systems PrecisionCore printhead productization, BOM management, ISO training
GitHub

---

License

📌 Item	License	Description
Source Code	MIT License	Free to use, modify, and redistribute
Text Materials	CC BY 4.0 or CC BY-SA 4.0	Attribution required; share-alike applies for BY-SA
Figures & Diagrams	CC BY-NC 4.0	Non-commercial use only
External References	Follow the original license	Cite the original source properly

---

Feedback

Suggestions, improvements, and discussions are welcome via GitHub Discussions.