Walabot‑Powered Toilet Hygiene Monitor

This system employs a Walabot RF sensor to determine whether a toilet is clean and whether it is currently in use, without the need for cameras.

Background

Why It Matters

Dirty or partially flushed public toilets are a widespread hygiene concern. Because a camera cannot be placed inside a toilet, alternative sensing technologies are required to detect contamination or occupancy before a user enters.

Walabot Technology

The Walabot is a programmable 3‑D imaging sensor that uses radio‑frequency waves to create a depth map of the environment without capturing optical images. By transmitting, receiving, and analyzing broadband signals from multiple antenna pairs, it reconstructs a 3‑D representation of objects behind obstacles—making it ideal for indoor applications where cameras are impractical.

How It Works in the Toilet

The sensor is mounted on the toilet’s roof. During initialization it scans a clean toilet. Subsequent scans, performed at 1‑minute intervals, detect any new object (e.g., a stool) that was absent during initialization. Because the initial state is known to be clean, any deviation indicates either the toilet has been used or is no longer clean. By measuring the distance to detected objects, the system can also determine if the toilet is currently occupied.

System Architecture

The complete solution consists of the following components:

• Walabot sensor
• Raspberry Pi 3 as the edge processor
• Ubidots cloud platform (MQTT for data upload)
• Android app built with MIT App Inventor for real‑time monitoring

The Raspberry Pi reads the Walabot output, evaluates the presence and distance of objects, and publishes the status to Ubidots using MQTT. The Android app retrieves the data via HTTP and displays whether the toilet is clean and/or occupied.

Installation & Configuration Steps

1. Install the Walabot SDK on Raspberry Pi
   Follow the “Getting Started” guide on Sparkfun.com to set up the SDK.
2. Install the Paho MQTT client
   Run sudo pip install paho-mqtt on the Pi.
3. Register on Ubidots
   Create an account at Ubidots.com and note your device token and ID.
4. Install the Ubidots API
   Run sudo pip install ubidots on the Pi.
5. Develop the Python Monitoring Script
   The script configures scanning parameters, identifies new objects, and sends status variables to Ubidots. Example configuration values:

   minInCm, maxInCm, resInCm = 30, 300, 3
   minIndegrees, maxIndegrees, resIndegrees = -15, 15, 5
   minPhiInDegrees, maxPhiInDegrees, resPhiInDegrees = -30, 30, 5
   threshold = 2

   The detection logic distinguishes between occupied, unoccupied‑but‑dirty, and clean states based on distance thresholds.

6. Build the Android App
   Using MIT App Inventor, create an app that fetches data from https://things.ubidots.com/api/v1.6/datasources/YOUR_OWN_DEVICE_ID/variables/?token=YOUR_OWN_TOKEN (replace placeholders) and displays the toilet status.

Testing & Validation

After deployment, the system was tested by manually introducing objects into the toilet and observing the real‑time updates on the Android device. The Python script’s detection thresholds were tuned to reliably identify small objects (e.g., a single stool) while ignoring background noise.

Key Code Snippet

if targets:
    for i, target in enumerate(targets):
        print(target.zPosCm)
        if 100 < target.zPosCm < 180:
            print("Toilet is engaged.")
            engage_variable.save_value({'value':1})
        elif 200 < target.zPosCm < 210:
            print("Toilet is not engaged, not clean.")
            engage_variable.save_value({'value':0})
            clean_variable.save_value({'value':1})
        else:
            print("Toilet is not engaged and clean.")
            engage_variable.save_value({'value':0})
            clean_variable.save_value({'value':0})
            break
else:
    print('Not engaged and clean')
    clean_variable.save_value({'value':0})
    engage_variable.save_value({'value':0})

Conclusion

By leveraging the Walabot’s non‑optical imaging, this system delivers a reliable, camera‑free solution for monitoring toilet hygiene and occupancy in real time. The combination of Raspberry Pi edge computing, Ubidots cloud connectivity, and an intuitive Android interface makes deployment straightforward for public facilities and businesses seeking to maintain high sanitation standards.