Views: 0 Author: Site Editor Publish Time: 2026-07-15 Origin: Site
A large steel mill has two 40-ton cranes in its cold rolling finished coil warehouse. The warehouse is about 120 meters long and 50 meters wide across two spans. These cranes handle all coil receiving, dispatch, and repositioning.
Before the retrofit, the operation relied entirely on manual driving. Operators worked long hours up in the cranes, which led to fatigue and safety concerns. Storage decisions were made on the spot based on experience, with no overall optimization. Inventory records were often out of sync and required frequent manual checks.
The goal was clear: run the cranes without operators, get each coil down in under 4 minutes, hit 99.99% accuracy, scan vehicles in less than 20 seconds, keep inventory accurate in real time, and cut the workforce significantly.
The project retrofitted both 40-ton cranes with full automation, covering positioning, control, and safety.
Positioning uses three methods working together: a Gray code busbar along the rail gives the bridge position with 1mm repeatability, a laser measures trolley travel, and an absolute encoder tracks hook height. This gives the crane accurate positioning in all three axes without the cumulative errors that come with traditional encoders.
The system actively adjusts bridge and trolley speed to cancel out load swing. It holds sway within ±0.5°, removes over 95% of the swing, and keeps positioning error under ±25mm. The 40-ton electric clamp comes with sensors for limit, load, centering, and clamping detection — so the grip is always secure.
Fixed LiDAR scanners at the loading bays create 3D point clouds of incoming trucks. The system identifies saddle positions, coil coordinates, truck skew angle, and the right picking direction. The whole scan takes under 20 seconds. The scanner head runs on servo motors with closed-loop control, accurate to below 0.0007°. After each scan, it retracts into a dustproof housing to keep the lens clean and reduce maintenance up high.
Before placing a coil, the LiDAR scans the target saddle and cross-checks with the crane PLC. This prevents three common mistakes: setting a coil down on top of another one, putting a second layer on a saddle that only has one coil underneath, or sending the crane to pick from an empty spot.
After each placement, the system logs the coil's exact position to within ±30-50mm, so the next pick is easy. It continuously scans all saddles and compares against the inventory database. Any mismatch triggers an immediate alert — no more manual counting.
The 3D management dashboard shows everything in the warehouse — columns, rails, guardrails, cranes, coils, and trucks — in real time.
Key functions:
Task scheduling: automatic or manual, with two optimization modes (full-warehouse or buffer-zone). The system can prestage coils based on production plans.
Fault diagnosis: shows live crane data and alerts, with history playback for troubleshooting.
Reports: export data by day, month, quarter, or year.
MES integration: receives production plans and sends back completion data automatically.
Mobile operation unit: a portable aluminum control panel for the central room — no cutout needed, plug and play. One unit can switch between cranes, useful for debugging, fault handling, or manual override.
Self-service kiosk and handheld terminal: the kiosk handles driver check-in and scanner activation; the handheld lets staff lock/unlock coils, check inventory, and look up coil data on the spot.
The system uses both Gray code positioning and laser ranging to monitor crane spacing — if two cranes get too close, it stops them automatically. Guardrails and interlocked access gates keep people out of the operating area. Flashing lights and alarms warn when a crane passes near walkways. Cameras on the cranes and around the warehouse give the control room a full view of everything.
After going live, both cranes have been running fully unmanned around the clock. All targets were met:
Single coil processing time: consistently under 4 minutes
Task accuracy: 99.99% for receiving, dispatch, and repositioning
Vehicle scanning: under 20 seconds
Headcount: cut by over 60%, no one needs to ride the cranes
Inventory: updates in real time, no manual counting, verification cost down over 90%
Data: fully traceable, all history exportable, real-time MES integration
Safety: zero incidents since startup
