Unattended truck weighbridge
A manually operated truck scale turned into a station that weighs, identifies and logs every truck with nobody on duty.
The hard part
A state machine that runs every weighing and every exception with nobody on duty.
What I built
Load cell and sensor layout, lightning protection, Modbus RTU I/O, traffic lights and LED signs, licence-plate recognition with my own YOLOX model and PaddleOCR, PostgreSQL, a web UI, an OPC UA server for the plant SCADA, and an offline Docker installer.
Result
Plate reads on 70 hard images rose from 66% to 94% after re-tuning. More than 500 automated tests, including end-to-end runs against a hardware simulator.
The problem
The plant’s truck scale needed an operator for every truck: someone to read the plate, record the weight and let the truck through.
What the station does now
- Six digital load cells, position sensors, traffic lights and LED signs guide each truck on and off the deck.
- A plate camera reads the licence plate with my own YOLOX detection model and PaddleOCR.
- The software follows each weighing from entry to exit and handles exceptions on its own, then logs the record in PostgreSQL.
- Field devices talk Modbus RTU; the plant SCADA reads the results through an OPC UA server.
- The whole system installs offline from a Docker package, so the site needs no internet connection.
Testing
More than 500 automated tests, including end-to-end runs against a hardware simulator that stands in for the scale, sensors and cameras.