# AI Agent Memory — HaydenProject

> AI agents working in this repo: read this file first for context, then update it when you make significant changes.

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## Project Identity

- **Repo:** https://git.molloyhome.net/mmolloy/haydenproject.git
- **Branch:** main
- **Owner:** Michael Molloy (dad) assisting Hayden Molloy (student)
- **Course:** AERO3220 — Aerospace Engineering, undergraduate
- **Assignment:** HW4, due 18 Feb 2026

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## What This Project Contains

| File | Description |
|---|---|
| `AERO3220_HW4.m` | Hayden's MATLAB script — solves a coupled two-mass spring-damper system across 5 parameter cases using `ode45` and plots results |
| `AERO3220_HW4.pdf` | Professor's original assignment PDF (image-compressed, not OCR-extractable) |
| `AERO3220_HW4_block_diagram.md` | Block diagram document created by AI agent — see section breakdown below |
| `.gitignore` | MATLAB + macOS ignores: `.DS_Store`, `*.pdf.png`, `*.asv`, `*.m~`, `slprj/`, `*.mex*`, `profile_results/` |

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## Physics Summary (AERO3220 HW4)

Two-mass spring-damper system. State vector: `x = [z1, z1dot, z2, z2dot]`.

Equations of motion:

- Mass 1 (top, unforced): `m1*z1ddot + k1*(z1-z2) = 0`
- Mass 2 (bottom, forced): `m2*z2ddot + b*z2dot + (k1+k2)*z2 - k1*z1 = u(t)`

Parameters:
- `k1 = 100 N/m`, `k2 = 50 N/m`, `m1 = 500 kg`, `m2 = 250 kg`
- Time: `t = 0` to `200 s`, `dt = 0.01 s`
- Initial conditions: all zero

Five simulation cases varying damping `b` and forcing `F`:

| Case | b (N·s/m) | Force u(t) |
|---|---|---|
| 1 | 100 | 100 N constant |
| 2 | 100 | 100 sin(0.25t) N |
| 3 | 0 | 100 sin(0.25t) N |
| 4 | 100 | 100 sin(0.50t) N |
| 5 | 0 | 100 sin(0.50t) N |

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## Block Diagram File Sections

`AERO3220_HW4_block_diagram.md` contains:

1. **Program Flow Block Diagram** — Mermaid flowchart of the MATLAB script execution (setup → 5 cases → 5 plots)
2. **ODE Model** — LaTeX equations for z1ddot and z2ddot
3. **System Equations Block Diagram** — Mermaid diagram of coupled dynamics signal flow (not a flowchart)
4. **Transfer Function Block Diagram Form** — Mermaid diagram with explicit gain blocks, integrator `1/s` blocks, and summation nodes. Includes Laplace-domain relations Z1(s) and Z2(s).
5. **Coupled State Space Form** — LaTeX `xdot = Ax + Bu` with full A and B matrices
6. **Assignment-Style Block Diagram** — Mermaid flowchart with a loop over cases (submission-oriented)
7. **Solver Subsystem** — Mermaid diagram zoomed into `eom_two_mass` internals

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## Known Mermaid Rendering Constraints

The repo viewer (Gitea at git.molloyhome.net) uses a strict Mermaid parser. These constructs **break rendering**:

- Square brackets `[...]` inside node labels (e.g. vector notation) — use plain text or parentheses-free descriptions
- Parentheses `(...)` inside `[...]` node labels — replace with plain text equivalents
- Math superscripts like `^T` inside labels — write out in words

Always test Mermaid node labels with plain alphanumeric text and spaces only inside `[...]` blocks.

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## Conversation History Summary

1. Michael shared the PDF (assignment) and `.m` file (Hayden's code).
2. AI read the MATLAB file and created `AERO3220_HW4_block_diagram.md` as a Mermaid flowchart of program flow.
3. Repo repointed to `https://git.molloyhome.net/mmolloy/haydenproject.git` (no prior remote existed), committed and pushed.
4. `.gitignore` added for MATLAB/macOS artifacts, committed and pushed.
5. Several Mermaid parse errors fixed iteratively (square brackets, parentheses in labels).
6. Hayden clarified: he wanted a **system equations** block diagram, not a program flowchart.
7. Added system-equations diagram, state-space form, and transfer-function block diagram with `1/s` integrator blocks and gain blocks.
8. This `MEMORY.md` and `README.md` created and pushed.

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## Agent Update Instructions

- After any meaningful change (new diagram, physics correction, new file), update the **Conversation History Summary** and **Block Diagram File Sections** tables above.
- If Mermaid parse errors are encountered, add the pattern to **Known Mermaid Rendering Constraints**.
- Do not remove prior history entries — append new ones.