Overhead Crane LiDAR Personnel Detection — Vehicle-Lane Safety Case Study from the Electric Power Industry

1. The Problem — Bridge Crane Operations Over an Active Vehicle Lane

The original case brief describes an electric-power maintenance hall where an overhead bridge crane shares space with vehicle and pedestrian traffic. Detailed customer records, rated crane capacity and commissioning results are not available with this article. Treat numerical geometry below as a worked example, not proof of a completed safety installation.

The three risks that drove this project:

• Personnel entering the lane while the crane is in motion with a suspended load — falling load risk plus the crane's travel can clip head clearance.
• Forklifts and service vehicles crossing the lane just as the crane arrives overhead — vertical and horizontal motion conflict, with the load being the highest-consequence intersecting object.
• Visual blind spots from the crane cabin — the crane operator sits 6+ m above the floor and the load itself often blocks the line of sight to the area immediately below the hook.

Three traditional safety measures were considered and rejected:

What was needed: a detection footprint that travels with the crane, doesn't physically obstruct the lane, and produces a deterministic stop signal regardless of operator attention.

2. The Solution — Tilt-Mounted 2D LiDAR With Two-Zone Interlock

The proposed monitoring layout combines three principles; each requires site verification:

• LiDAR mounted on the crane itself — so the detection footprint travels with the crane; coverage of the actual hazard must still be verified at every relevant load, hoist and travel position. Movement of the sensor does not guarantee uninterrupted detection.
• Tilted scan plane (~20° downward) — the LiDAR is angled so its scan plane intersects a flat floor along a line, not a filled fan-shaped protective floor area. Evaluate where the plane intersects the objects that must be detected. Hook, chain and load positions can enter or shadow the plane and must be checked throughout travel and hoist movement.
• Two-zone polygon fields with graded response — an outer warning zone triggers slow-down (giving people time to clear), and an inner protective zone triggers immediate stop (the hard floor). This matches the general warning/stop concept. Ordinary LiDAR detection zones do not inherit the safety rating of a certified protective field.

The hardware chosen was the DAIDISIKE DLD30T-5N — a non-safety perception LiDAR. The current factory table lists 30 m at 90% remission and 10 m at 10% remission, with Ethernet point-cloud output. The older 40 m label and dry-contact/RS-485 descriptions must not be used as a wiring specification. Consult the LiDAR family by sensing and safety function and the exact model documents before selection.

3. Scan-Zone Geometry — Calculating the Tilt Angle

The center ray of a 2D scanner mounted at height H and tilted down by θ intersects a level floor at horizontal distance R = H / tan(θ). Slant distance to that point is H / sin(θ). These describe one ray, not a ring or a filled protected floor area.

For the center ray, the horizontal distance formula is:

Illustrative geometry only: H = 6 m and θ = 20°. These are not verified customer measurements:

The center ray reaches the floor about 16.5 m horizontally away and about 17.5 m along the beam. Other azimuths have different intersections; a 270° scan does not fill the floor area beneath the crane. Compare slant range with the target-reflectivity limit and assess people, loads and occlusions throughout the full motion envelope.

The table gives center-ray horizontal distances only. It does not determine lane coverage or a safety margin. Use a three-dimensional layout and controlled detection tests at relevant target heights; verify shadowing by the load and crane structure.

4. Installation Walkthrough — 8 Steps from Survey to Acceptance Test

The eight steps below are an engineering review workflow. No installation duration, cost or successful acceptance result is established by the source material available here.

5. Interlock Wiring — Tying LiDAR Outputs Into the Crane Control Loop

The table describes intended functions, not DLD30T-5N pin assignments. Confirm the exact output hardware and use a suitably rated independent detection/control chain wherever personnel safety is required.

A safety relay such as DAIDISIKE DA31 cannot add missing safety integrity to a non-safety LiDAR. Establish the required safety performance for sensing, logic, braking and final elements together; verify compatibility from the manuals. Preserve existing crane safety functions and address suspended-load hazards separately.

For event logging, first confirm the actual interface and available data fields. Do not assume built-in timestamps, zone IDs or Modbus registers. Diagnostic data may support maintenance but does not prove a safe stop.

6. Hardware Recommendation

DAIDISIKE DLD30T-5N — non-safety perception

• Detection range: factory table: 30 m at 90% remission; 10 m at 10% remission.
• Scan rate: 10–30 Hz; scan frequency is not a certified safety response time.
• Laser: 905 nm Class 1; this does not establish functional safety.
• Enclosure: IP67; assess actual contamination and cleaning exposure.
• Interface: current factory table lists Ethernet point-cloud output; confirm the delivered variant.
• Body: current table: 50 × 50 × 76 mm, 148 g; check installation drawings.
• Operating temperature: −10 °C to +55 °C; storage limits are different.

Shorter-range alternatives for lower cranes: the DLD05A3-3N / DLD20A5-5N (5 m / 20 m) for jib cranes and small bridge cranes; the 5JPTG / 10JPTG (5 m / 10 m) for ultra-compact installations.

7. Where This Same Pattern Applies — Beyond Electric Power

The customer in this case study is in the electric power industry, but the underlying safety pattern — moving overhead equipment + shared ground-level traffic area — appears in many other industries where the same LiDAR + tilt-mount + interlock concept requires a fresh risk assessment and design:

8. Results Evidence Required Before Reusing the Design

• Incident evidence: obtain dated incident and near-miss records with a defined observation period.
• Availability evidence: classify warning events, stops and false detections against logged operating cycles and conditions.
• Safety evidence: retain verified detection coverage, stopping tests and fault response; absence of incidents alone does not validate safeguarding.
• Commercial evidence: confirm installation cost, labor and rollout scope from project records before quoting them.
• Current limitation: the previous numerical outcome, payback and rollout claims cannot be substantiated from the material provided with this article; they are not presented as measured results.

9. Frequently Asked Questions

10. Related Reading

Have a Similar Crane Safety Application?

Provide crane height, lane geometry, load envelope, permitted motion, required safety function and environmental conditions. These let engineering assess whether the proposed sensing geometry is suitable and what documentation and validation are needed. No response time or reference drawing availability is promised here.