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Robotics & AutomationEngineering Study

On-Device Edge Vision Defect Detection on ESP32-S3

For an electronics-assembly client, YantriX designed a custom inspection camera that flags solder and placement defects on-device. The whole pipeline — sensor, model, firmware, enclosure — fits in a fanless 40 x 40 x 25 mm module.

By YantriX Engineering · Edge AI Studio2 min readElectronics manufacturing
Edge AI defect detection camera on electronics assembly line

Overview

Engineering Scope & Context

A production conveyor inspection camera running a quantized INT8 CNN entirely on an ESP32-S3 — 18 FPS at 0.4 W, no cloud, 6× lower capex per station.

Engagement: Engineering Study

Discipline: Robotics & Automation

Project Type: Edge AI + Custom Hardware

Application: Electronics manufacturing

Key specifications

Core engineering parameters & stack.

18 FPS
Continuous on-device inference
0.4 W
Steady-state power draw
96.8%
Validation accuracy
Lower capex per station

Objectives

What the project needed to achieve

  • Detect defined defect classes on placed components with production-grade accuracy
  • Run the model entirely on microcontroller-class hardware
  • Eliminate cloud and on-prem PC dependencies
  • Fit into a compact, fanless enclosure mountable above the conveyor

Challenge

Engineering constraint

The client had a line-side PC-based vision rig that was expensive to scale across many stations and introduced a cloud dependency the plant IT policy didn’t allow. They wanted a self-contained inspection module per station — low power, low cost, zero external dependencies.

Approach

How YantriX approached the work

  1. 01

    Captured a labelled dataset of nominal and defective assemblies across lighting variants at the client plant.

  2. 02

    Designed a compact CNN sized for ESP32-S3 constraints and trained it with aggressive INT8 quantization-aware training.

  3. 03

    Designed a custom 4-layer PCB combining ESP32-S3-WROOM, an OV5640 camera module, a local ring light, and MQTT telemetry over Wi-Fi.

  4. 04

    Delivered firmware with a ring buffer for failure-case capture so the client can periodically retrain from real edge cases.

Outcomes

What improved by the end

  • 18 FPS continuous inference at approximately 0.4 W steady-state
  • 96.8% accuracy on the validation set; on-line operator override provided for ambiguous cases
  • No PC, no cloud — fully autonomous per-station operation
  • Unit cost reduced to a fraction of the previous PC-based rig
  • Failure-case ring buffer enables continuous dataset growth

Deliverables

What the client receives

  • Custom PCB design files and fabrication package
  • Quantized INT8 model and training pipeline
  • FreeRTOS firmware with OTA update path
  • Enclosure CAD with thermal and mounting study
  • Commissioning report and retraining playbook

Tools used

Stack and tooling

  • ESP32-S3-WROOM-1 (8 MB PSRAM)
  • OV5640 camera module
  • TFLite Micro with ESP-DL acceleration
  • PyTorch (quantization-aware training)
  • KiCad for PCB design
  • FreeRTOS firmware
  • MQTT for telemetry

Impact

Business-level effect

  • Inspection coverage extended from selected stations to the entire line
  • Capex per station reduced by roughly 6× vs. the PC-based alternative
  • Plant IT policy satisfied — no external network traffic required

Conclusion

The project shows that thoughtfully quantized models plus hardware co-design can put real-time ML into truly constrained devices — not just on single-board computers.

Working on a similar engineering problem?

Need an inspection system that scales across dozens of stations without a PC fleet? We design the device, the model, and the firmware as one thing.

Tagged

  • ESP32-S3
  • TFLite Micro
  • Edge AI
  • Quantization
  • PCB Design
  • Defect Detection

Frequently asked questions

Answers from the engagement itself.

Can you really run a useful vision model on an ESP32-S3?

Yes — for narrow, well-scoped problems. A 320×320 INT8 CNN with under ~1.5M parameters runs at 15–20 FPS on the ESP32-S3 with ESP-DL acceleration. Defect detection, presence/absence checks, and SKU classification all fit. Object detection across many classes does not.

How does an ESP32-S3 inspection module compare on cost to a PC-based rig?

BOM landed around ₹6,000–12,000 per station versus ₹75,000–1,50,000 for a PC + industrial camera setup. Power per station drops from ~80 W to under 1 W, which compounds over hundreds of stations across a plant.

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