sonar180

Great precission and compact end-to-end ultrasonic scanning system that performs a 180° sweep, streams distance data in real time, and renders it live in the browser as a radar, heatmap, and radial 3D visualization.

Overview

The system is composed of three layers:

1. Arduino firmware

   • Drives a servo from 0–180°.
   • Triggers an ultrasonic sensor at each angle.
   • Outputs measurements over serial as:

     angle:distance
     

     Example: 72:135 (72°, 135 cm).

2. Python backend

   • Reads the serial stream.
   • Maintains the latest distance per angle (0–180).
   • Detects sweep direction changes and full sweeps.
   • Exposes a lightweight HTTP server.
   • Streams data to the browser using SSE (Server-Sent Events).

3. Web frontend

   • No build step, pure HTML/JS.
   • Real-time visualizations:
     • 2D semicircular radar.
     • Time-scrolling heatmap (per sweep).
     • Radial pseudo-3D bar scene.
   • Live controls (range, threshold, smoothing, pause, capture).

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Highlights / Key Technical Features

• Dynamic echo waiting

  • The Arduino firmware does not use a fixed blocking delay.
  • Echo wait time is dynamically bounded, allowing fast returns at short distances while still supporting accurate long-range measurements.
  • This maximizes sweep speed without sacrificing precision.

• True 180° continuous sweep

  • Servo movement is monotonic with direction tracking.
  • Direction changes are detected on the backend to delimit complete sweeps reliably.

• Per-angle state model

  • One distance value per degree (0–180).
  • Constant-time updates and rendering.
  • No frame-based recomputation or resampling.

• Sweep-aware data streaming

  • Backend emits:
    • single-point updates (low latency),
    • full sweep snapshots (coherent frames),
    • sweep boundary events.
  • Enables heatmaps and temporal analysis without guesswork.

• Low-latency real-time transport

  • Uses Server-Sent Events (SSE) instead of polling or WebSockets.
  • Stateless, efficient, and browser-native.

• Optional EMA smoothing

  • Exponential Moving Average per angle.
  • Reduces ultrasonic noise while preserving spatial structure.

• Multiple synchronized views

  • Radar (geometric accuracy).
  • Heatmap (temporal persistence).
  • Radial 3D bars (depth perception).

• Distance-coded color pipeline

  • Unified color logic across all views.
  • Near/far separation is immediately readable.

• Zero build, zero framework frontend

  • Single HTML page.
  • No bundler, no transpilation, no dependencies.

• Sensor-agnostic architecture

  • Serial protocol and backend logic are generic.
  • Can be reused with LiDAR, ToF, IR, or RF ranging sensors with minimal changes.

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Visualizations

• Radar: current sweep with distance-coded colors.
• Heatmap: vertical history of completed sweeps.
• Radial 3D scene: bars positioned by angle and distance, color-graded from near to far.

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Files

• sketch_sonar.ino
  Arduino firmware (servo + ultrasonic sensor, serial output).

• sonar.py
  Full dashboard version (radar + heatmap + radial 3D, Canvas-based).

• sonar_aframe.py
  Minimal version using A-Frame for a true 3D scene in the browser.

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Requirements

Hardware

• Arduino (Uno / Nano / compatible)
• Servo motor
• Ultrasonic sensor (HC-SR04 or similar)

Wiring:

• SENSOR: VCC to 5V. GND to GND. TRIGGER to D8. ECHO to D7.
• SERVO: VCC to 5V. GND to GND. SIGNAL to D9.

Software

• Python ≥ 3.8
• Python dependency: pip install pyserial

How to use

• Upload sketch_sonar.ino to your Arduino
• Keep conected to PC to use serial port
• Run one of the python servers:

python3 sonar.py --port /dev/ttyACM0 --baud 115200 --http 8000

or

python3 sonar_aframe.py --port /dev/ttyACM0 --baud 115200 --http 8000

(Adjust the serial port if needed, e.g. COM3 on Windows.)

Open the dashboard using your browser: http://127.0.0.1:8000

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LICENSE

CC BY 4.0