System Architecture
Input adapters route user intent through safety logic before relay activation.
Hands-Free Door Access
A safe, multi-modal door activation system for users who can’t press the accessible door button.
Accessibility / Assistive Tech / Embedded SystemsReference build
Problem
Some users cannot reliably press a wall plate or accessibility button even when automatic doors are available.
The control path must be hands-free, dependable, and safety-aware, with minimal false activation risk and no disruption to existing door controls.
System Architecture
The hub is organized around provisioning, device control, MQTT messaging, and firmware lifecycle management so the system stays understandable as more devices are added.
State Machine
Idle, detect, confirm, trigger, and cooldown transitions designed for safer activation behavior.
Parallel Relay Wiring
Relay path is wired in parallel so existing accessible button operation remains intact.
Hardware & Software Stack
| MCU | ESP32 |
|---|---|
| Inputs supported | NFC, app trigger, assistive switch, proximity modes |
| Output type | Relay contact (parallel trigger path) |
| Installation mode | Parallel with existing accessible button |
| Logging | Local logs + optional Google Sheets export |
| Connectivity | BLE / Wi-Fi (config dependent) |
How It Works
1. Detect intent
Input arrives from configured sources such as NFC, assistive switch, app trigger, or proximity channel.
2. Confirm
Safety logic checks confirmation window and optional multi-signal gating before actuation.
3. Activate relay
Relay closes in parallel with existing button input to request door opening.
4. Log and cooldown
Event is recorded and cooldown timer enforces spacing before the next trigger attempt.
Build Resources
Supporting artifacts for architecture review, collaboration, and follow-up implementation planning.
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