44 lines
1.8 KiB
Markdown
44 lines
1.8 KiB
Markdown
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# Decision: Shared Modern PID in generalFunctions + PumpingStation Flow-Based Adoption
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- Date: 2026-02-23
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- Scope: `nodes/generalFunctions/src/pid/*`, `nodes/pumpingStation/src/*`
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## Context
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Flow-based control in `pumpingStation` needed a production-grade PID with freeze/unfreeze, runtime retuning, and support for cascade/secondary-loop architecture.
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## Options Considered
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1. Implement PID only inside `pumpingStation`.
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2. Implement shared PID in `generalFunctions` and consume it from `pumpingStation`.
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3. Keep current heuristic (non-PID) flow controller.
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## Decision
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Chose option 2.
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## Rationale
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- PID behavior is cross-domain control functionality and should be reusable across EVOLV nodes.
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- `generalFunctions` already serves as shared utility/runtime infrastructure.
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- Reuse reduces drift and duplicated control logic.
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- PumpingStation can immediately adopt shared PID while preserving existing topic contracts.
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## Consequences
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- Positive:
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- Single, test-covered PID implementation with modern features.
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- PumpingStation flow mode becomes true closed-loop control.
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- Runtime support for freeze/unfreeze and tuning updates without redeploy.
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- Risks:
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- Behavioral differences versus prior heuristic flow control.
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- Requires conservative tuning per site.
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## Safety / Compatibility
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- No existing topic names were removed.
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- Added optional control topics for PID runtime management.
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- Existing non-flowbased modes remain intact.
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## Rollback
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- Revert `nodes/pumpingStation/src/specificClass.js` flow-based branch to previous heuristic logic.
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- Keep shared PID module in `generalFunctions` for future use, or revert `nodes/generalFunctions/src/pid/*` if required.
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## Migration Notes
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- For `flowbased`, start with low `kp/ki`, verify stability in commissioning, then tune upward.
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- Use `freezeFlowPid` and `setFlowPidMode` during maintenance or manual takeover.
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