Project

# Title Team Members TA Documents Sponsor
2 Non-Shock Ultra-Wideband Virtual Boundary Pet Collar
 Peter Gao
Shi Xian Chng
Shi Yang Ng
 Tianda Huang
# Non-Shock Ultra-Wideband Virtual Boundary Pet Collar

**Team Members:**
- Yujia (Peter) Gao (peterg4)
- Shi Xian Chng (schng2)
- Shi Yang Ng (syng2)

## Problem

Existing wireless pet fences are unreliable indoors: GPS gives 3–5 m error and RSSI 1–2 m, environment-dependent. There is a need for an indoor virtual boundary that people can walk through but pets are trained to avoid, without physical barriers or electric shock.

## Solution

Wall-powered UWB anchors placed in a chain define virtual wall segments. A collar measures its distance to adjacent anchors via UWB two-way ranging, computes its distance to the nearest wall segment locally using anchor spacings, and gives progressive vibration → sound feedback as the pet approaches. No central controller, fail-safe on link loss or low battery, high precision.

Anchor and collar share one custom PCB with different populations. Role and anchor ID are assigned at flash time, so any spare board can replace any node.

# Solution Components

## Anchor System

### Ranging Subsystem

- **Hardware:** Qorvo DWM3000 UWB module communicating via SPI, with a dedicated RF antenna keep-out zone along the board edge.
- **Software:** responds to collar polls with timestamps for double-sided two-way ranging. Self-surveys neighbor distances at power-up, re-verifies periodically; spacings ride in response payloads, large changes trigger a fault state. Ranging frames double as the data channel.

### Control Subsystem

- **Hardware:** Espressif ESP32-C3-MINI-1 microcontroller module, status indication LEDs, and test points/headers for USB-serial programming and debug.
- **Software:** anchor state machine - respond to polls by ID, schedule surveys, manage faults. Debug logs over USB serial.

### Power Subsystem

- **Hardware:** USB-C connector for 5 V wall power input, AP2112K-3.3TRG1 LDO linear voltage regulator (3.3 V, 600 mA output), input/output MLCC decoupling capacitors, and unpopulated footprints for battery charging/feedback circuitry.

## Collar System

### Ranging Subsystem

- **Hardware:** Qorvo DWM3000 UWB module connected over SPI with matching antenna keep-out layout identical to the anchor design.
- **Software:** polls each anchor by ID, computes time-of-flight; collects spacings and status from responses.

### Control Subsystem

- **Hardware:** Espressif ESP32-C3-MINI-1 microcontroller module, system status LEDs, and programming/debug headers.
- **Software:** computes distance to each wall segment from two anchor ranges and the segment length, takes the minimum, and runs the feedback state machine (safe → warning → boundary) with hysteresis. Fail-safe on link loss or low battery. BLE for debug telemetry and stretch-goal phone notifications.

### Feedback Subsystem

- **Hardware:** Piezo buzzer (TDK PS1240P02BT or CEM-1203), coin vibration motor (Vybronics VC1030B028F / 2265 ERM), dedicated haptic motor driver (TI DRV2603) or discrete N-channel switching MOSFET, with a flyback protection diode.
- **Software:** maps zone to output - vibration in warning, escalating to tone at boundary.

### Power Subsystem

- **Hardware:** 3.7 V (150–500 mAh) Li-Po battery with JST connector, Microchip MCP73831 charge management controller, integrated battery protection circuit (DW01A protection IC + FS8205A dual N-channel MOSFET), AP2112K-3.3TRG1 LDO regulator, USB Type-C charging port, and charge status LEDs.
- **Software:** battery monitoring for low-battery fail-safe; duty-cycled ranging for battery life.

## Criterion For Success

1. Collar to wall distance error ≤0.5 m (UWB achieves 0.1 m to 0.3 m of accuracy) at 10 tape-measured test points, including through a doorway and with obstacles.
2. Feedback within 50 ms of entering the warning zone, correct vibration→tone escalation. Cats/dogs can run at 13 m/s; assuming wall deterrent radius is 1 m, we need to detect it within at least 0.077 s to avoid sprint-throughs.
3. Stable output during 15 minutes stationary on the boundary between vibration and neutral zones.
4. Fail-safe within 10 seconds if the pet gets stuck in the deterrent zone.
5. ≥24 hr collar battery life (assuming no vibrations and sound).
6. Collar weight < 60 g.

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