Measuring 100 m Blade Layup From Stations Every 6 to 8 m
Offshore blades have reached the 100-metre class, and layup happens in place on the shop-floor mould. Ply pieces, core material and fittings are positioned by eye and tape measure, so accuracy is uncontrolled and deviation cannot be quantified. Once a blade is cured, internal layup defects are effectively not reworkable, so measurement has to happen during layup, quick enough to sit between layup steps and light enough not to occupy the mould surface. Spar and web bonding positions depend on manual marking in the same way, and their accumulated deviation usually surfaces at mould closure.
Segmented stations, one mould coordinate frame
One group of stereo cameras and LiDAR cannot cover a hundred metres. A group is deployed every 6 to 8 metres along the blade axis, fixed overhead above the mould and out of the working area, with neighbours overlapping so coverage is continuous. Calibrating each group on its own would be pointless: they must be brought into one mould coordinate frame, or a datum jump appears at every seam. That is the first technical crux of the scheme.
What stereo does, what LiDAR does
The division is complementary, not duplicated:
- Stereo vision uses parallax to give the precise 2D position of ply edges and reference lines.
- LiDAR gives wide-range 3D distance, resolving the conflict between measuring accurately and reaching far enough.
- A laser reference line is projected along the blade axis as the single measurement reference for the whole blade, and it also positions the spar and locates the web bond.
Measure, report, adjust, re-measure
- The operator triggers the check manually at a layup inspection node.
- That group's stereo cameras and LiDAR capture together while the laser line is projected on the mould.
- Ply edges, core boundaries, fitting positions and the reference line are extracted from image and cloud, and the lateral deviation is computed.
- The two data sources are fused and the deviation is compared with the allowed tolerance.
- An over-limit result raises an immediate alarm, the operator adjusts, and re-measures once the material is in place.
One measurement takes about 90 seconds. Each group's result is archived with a timestamp and its axial position, building a complete record of the layup process.
Why manual triggering instead of continuous scanning
Material state keeps changing during layup, and continuous scanning produces large volumes of invalid data and false alarms. Triggering at work nodes aligns measurement with the process, so the data is targeted. That is the biggest difference from online continuous inspection.
Four difficulties on site
| Difficulty | Handling |
|---|---|
| Hundred-metre coverage | A group every 6 to 8 m, jointly calibrated into one frame |
| Fusing two data sources | Joint calibration plus fusion, keeping stereo precision and LiDAR range |
| Vibration and occlusion | Fixed overhead mounting damps vibration; triggered capture works in a static window |
| Material colour and texture | Geometric features dominate, so appearance matters less |
Effect and boundaries
Layup deviation is quantified in real time instead of judged by eye, the data is recorded for process improvement and traceability, and the spar and web positions are guided by the laser line.
The boundary is centimetre-level layup deviation. Station spacing follows workpiece length, and shop height, crane clearance and vibration have to be assessed. Mould environments differ widely between shops, so the layout should be finalised after on-site measurement and calibration. Figures are subject to site acceptance results.
Blade layup questions
Why can one set of equipment not cover a whole blade?
Stereo and LiDAR fields are finite and cannot span a hundred metres. Groups every 6 to 8 m, jointly calibrated into one frame, give full-length coverage with a consistent datum at the seams.
How are the two sensor streams combined?
Each group is calibrated jointly, then all groups are brought into the mould frame. The fused data computes deviation against the laser line, keeping stereo precision and LiDAR range.
Is the laser line only for measurement?
No. It is the common reference for layup deviation and also locates the spar and the web bond, so one reference serves both measurement and assembly.
What happens after an alarm?
The system shows the deviation, the operator adjusts the material, and re-measurement is triggered, closing the measure-report-adjust-re-measure loop without disturbing the layup rhythm.