# Plate Wall Offset Measurement for U-Shaped Groove Workpieces Based on Multi-Line-Structured Light Vision Sensors

## TL;DR

This paper introduces a precise method using multi-line-structured light sensors to measure plate wall offsets in U-shaped grooves of large cylindrical shells.

## Contribution

A novel measurement method using multi-line-structured light vision sensors for accurate plate wall offset detection in U-shaped grooves.

## Key findings

- The method achieves a measurement uncertainty of ±0.015 mm for a 30 mm standard sphere.
- Within a defined range, the sensor shows ±0.013 mm uncertainty, closely matching reference values.
- The approach effectively separates and computes distances between plate wall regions in U-shaped grooves.

## Abstract

To address the challenge of measuring the plate wall offset at the U-shaped groove positions after assembling large cylindrical shell arc segments, this paper proposes a measurement method based on multi-line-structured light vision sensors. The sensor is designed and calibrated to collect U-shaped groove workpiece images containing multiple laser stripes. The central points of the laser stripes are extracted and matched to their corresponding light plane equations to obtain local point cloud data of the measured positions. Subsequently, point cloud data from the plate wall regions on both sides of the groove are separated, and the plate wall offset is calculated using the local distance computation method between planes in space. The experimental results demonstrate that, when measuring a standard sphere with a diameter of 30 mm from multiple angles, the measurement uncertainty is ±0.015 mm within a 95% confidence interval. Within a measurement range of 155 mm × 220 mm × 80 mm, using articulated arm measurements as reference values, the plate wall offset measurement uncertainty of the multi-line-structured light vision sensor is ±0.013 mm within a 95% confidence interval, showing close agreement with reference values.