Project: OpenAssistive — Modular Assistive Mobility System
Document: Bill of Materials (BOM) v1.0
Author: Milton Rodolfo Amador Zúniga
Copyright (C) 2026 Milton Rodolfo Amador Zúniga

License: GNU General Public License v3 (GPLv3)

This project is Free Software and Open Hardware.
This is a non-profit open social technology initiative.

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# OpenAssistive — Bill of Materials (BOM) v1.0

## 1. Scope

This BOM defines the recommended components for building the OpenAssistive
Mobility System Prototype v1.

Goals:

- low cost
- global availability
- modular replacement
- repair-friendly
- no proprietary lock-in where possible

Prices are indicative and may vary by country.

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# 2. Core Compute Module (Backpack Unit)

## 2.1 Single Board Computer

Primary Option:
- Raspberry Pi 4 (4GB or 8GB)
- Estimated cost: 60–90 USD

Alternative Low-Cost:
- Raspberry Pi 3B+
- Used/refurbished units acceptable
- Estimated cost: 35–55 USD

Reason:
Provides sufficient compute for camera + QR + audio.

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## 2.2 Storage

- MicroSD Card 64–128 GB (high endurance preferred)
- Estimated cost: 10–20 USD

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## 2.3 USB Audio Adapter

- Generic USB sound card dongle
- 3.5mm jack
- Estimated cost: 5–10 USD

Reason:
Improves audio reliability vs onboard jack.

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# 3. Cane Sensor Module

## 3.1 Distance Sensors (ToF)

Recommended:
- VL53L1X ToF sensor modules ×2
- Range: up to ~4m (practical ~2–3m)
- Estimated cost: 8–15 USD each

Alternative:
- VL53L0X (shorter range, cheaper)
- Estimated cost: 5–8 USD each

Mounting:
Front + slight angle side.

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## 3.2 Microcontroller

Recommended:
- ESP32 Dev Board
- Built-in BLE/WiFi
- Estimated cost: 6–12 USD

Alternative:
- RP2040 board
- Estimated cost: 5–10 USD

Role:
Sensor timing + preprocessing.

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## 3.3 Protective Housing

- Small project box (plastic)
- Or 3D printed case
- Estimated cost: 3–8 USD

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# 4. Haptic Feedback

## 4.1 Vibration Motors

- Coin vibration motor ×2–4
- 3–5V type
- Estimated cost: 2–4 USD each

Locations:
- Cane handle (primary)
- Chest/strap (optional)

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## 4.2 Motor Driver

- Small transistor or MOSFET board
- Or ULN2003 driver
- Estimated cost: 2–5 USD

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# 5. Camera Module

## 5.1 Camera

Primary:
- Raspberry Pi Camera Module v2/v3
- Estimated cost: 25–40 USD

Alternative:
- USB webcam (wide angle preferred)
- Estimated cost: 15–30 USD

Mount:
Backpack shoulder strap clip mount.

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## 5.2 Microphone

- Lavalier mic (3.5mm)
- Estimated cost: 8–15 USD

Alternative:
- Headset inline mic

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# 6. Audio Output

## 6.1 Earphone

Primary:
- Mono earbud with inline button
- Estimated cost: 5–15 USD

Better Option:
- Bone conduction headset
- Estimated cost: 35–80 USD

Reason:
Keeps ears open to environment.

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# 7. Power System

## 7.1 Battery

- USB Power Bank 20,000 mAh
- Output: 5V / 3A
- Estimated cost: 25–45 USD

Requirement:
Must support continuous 3A output.

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## 7.2 Power Cable

- Short USB cable (reinforced)
- Estimated cost: 3–6 USD

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# 8. Cabling & Connectors

## 8.1 Magnetic Breakaway Connector

- 2–4 pin magnetic connector
- Estimated cost: 5–12 USD

Use:
Cane-to-backpack safety disconnect.

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## 8.2 Wiring

- Flexible silicone wire
- JST connectors
- Heat shrink tubing
- Estimated bundle: 10–20 USD

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# 9. Textile Integration

## 9.1 Vest / Harness

- Lightweight vest or backpack harness
- With cable routing channels
- Estimated cost: 15–35 USD

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## 9.2 Velcro / Straps

- Industrial velcro strips
- Elastic bands
- Estimated cost: 5–10 USD

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# 10. Optional Modules (Not Required v1)

- GPS USB module — 15–25 USD
- BLE beacons — variable
- Extra haptic zones — variable
- Wireless cane link — future

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# 11. Estimated Prototype Cost (v1)

Low-cost build:

- Minimum: ~180 USD
- Typical: ~220–260 USD
- With bone-conduction audio: ~300+ USD

Goal:
Further reduce with donations and bulk sourcing.

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# 12. Replacement Philosophy

All parts should be:

- individually replaceable
- globally sourceable
- non-proprietary
- documented equivalents allowed

No vendor lock-in.

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End of BOM v1.0
OpenAssistive Project