A 45-Meter Stacker Crane Survived a 5.5 Magnitude Earthquake — Here's What the Inspection Found

On August 6, 2023, a magnitude 5.5 earthquake struck Pingyuan County in Shandong Province. BlueSword's 45-meter ultra-high automated stacker crane system, was located just 29 kilometers from the epicenter and experienced significant shaking. What happened next is a useful look at how seismic protection actually holds up under real conditions, not just design specs.

The First Check: A Visual Inspection

Within hours, BlueSword's technical team began a visual inspection of the automated stacker crane area — checking rack structural appearance, stacker crane integrity, pallet displacement, and any visible deformation. The seismic-resistant racking design showed no visible abnormalities, but the team went further, activating the system's SPS safety early-warning system for a deeper diagnostic across the entire warehouse zone.

What the Gyroscope Sensors Showed

Gyroscope sensors mounted on the stacker crane continuously track tilting or swinging in both static and dynamic conditions — in static mode checking structural deviation in the mast and beams, and during low-speed operation assessing the health of floor and overhead rail systems. Data analysis after the earthquake found no abnormalities in either the crane structure or the rail systems.

Sampling Check Across the Warehouse

Because strong seismic vibration can misalign rack columns and beams in ways that aren't visible, BlueSword uses an ETI smart electronic pallet system — sensors mounted on an electronic pallet extended into storage locations via the stacker crane forks — to rapidly check rack verticality, horizontality, and structural deviation across zones. Across the system's 3,754 storage locations, the team sampled 187 (a 5% sampling rate) and found no abnormalities in verticality or horizontality.

Confirming Nothing Was Sitting Where It Shouldn't Be

Shaking can also shift pallets enough that goods protrude into a stacker crane's operating space. The system's front-end spatial safety sensor covers full 45-meter vertical intrusion detection, and a low-speed pass across the entire travel path after the earthquake confirmed the operating space remained clear. A small number of pallets — 45 in total — showed minor displacement, with a maximum shift of 2.7cm, none of which affected normal operation.

Built-In Protection Against What Inspection Might Miss

Beyond inspection, BlueSword's cranes carry both contact and non-contact anti-collision protection as a standing safeguard. A contact sensor at the fork's front end detects abnormal contact with a displaced pallet, reports it within 30ms, and halts fork movement within a 50mm safety range — preventing cargo from being pushed off the rack during handling.

A separate non-contact 3D vision system checks for pallet displacement, angle deviation, or damaged fork openings before a pickup action executes, issuing a warning or blocking the operation automatically if something looks unsafe — reducing both the immediate safety risk and the downtime that comes from a failed pickup.

BlueSword's product philosophy centers on what it calls meaningful innovation — the kind of standard a stacker crane manufacturer needs to meet when a system like this one is tested by something as unplanned as an earthquake. The earthquake provided an unplanned real-world test of that principle, and the inspection results offer evidence that a specification sheet alone cannot provide.