Cylindrical Surface Defect Inspection

Project Background

Inspection Background

For cylindrical objects such as batteries, bearings, pipes, etc., surface quality directly affects their performance and lifespan. To ensure the high quality of these products, strict quality control of the cylindrical surface is essential, particularly for inspecting surface defects (like scratches, dents, cracks, bubbles, etc.). This project aims to develop a non-contact cylindrical surface defect inspection system. It uses rotational scanning technology to unwrap the entire cylindrical surface into a flat image, which is then divided into eight regions (slices) for detailed inspection.

Camera Selection

Shenshi SR700

Inspection Items

Cylindrical surface defects

Solution

AI-Vision first preprocesses the point cloud image, then crops out the eight slices requiring inspection for surface defect detection.

Design Approach

Execution Results Showcase

• Project Results Display

  • Surface Defect Inspection Results

  

Project Process

1. Initialization

1. Use Lua Script to set a global variable for loop counting.

SetIntVariable("Count", 0)

2. Use the Load Point Cloud tool to load the point cloud image that needs processing.

2. Preprocessing

1. Use the 3D Region tool to select the region for plane fitting.

2. Use the 3D Plane tool, bound to the region set by the 3D Region tool, to fit a plane and set it as the zero plane.

3. Surface Inspection for Different Slices

1. Select the Marker tool to set the loop starting point.

2. Use the Lua Script tool to calculate the cylindrical slice region to be cropped and push the box coordinates.

x = 23.5

sx = (x + count * 10) - 5
sy = 0
sz = -5

ex = (x + count * 10) + 3.6
ey = 26
ez = 5

SetBox("box", sx,sy,sz,ex,ey,ez)

3. Use the 3D Crop tool, bound to the output variable box from the previous Lua Script step as the input region, to crop out the cylindrical slice to be inspected.

4. Use the 3D Surface Defect tool to run the inspection and obtain information about dent or protrusion defects on the current cylindrical slice.

5. Use the Lua Script tool

   • Bind to the output variable (defect information) from the previous 3D Surface Defect tool.
   • Edit the Lua script to format the information and display it on the corresponding IM window.
   • Determine if the loop should end.

Note

string.format is used to format strings. %.nf formats a floating-point number to keep n decimal places. Example:

pi = 3.14159 str = string.format("Pi is approximately %.3f", pi) print(str) -- Output: Pi is approximately 3.142

-- Defect count
defectcount = #defect_area

-- Loop to display defect height
for i=1, defectcount, 1 do
    -- Get defect centroid position
    x = defect_centroid_x[i]
    y = defect_centroid_y[i]
    
    -- Current defect information, formatted to 3 decimal places
    height = string.format("%.3f", defect_height[i])
    area = string.format("%.3f", defect_area[i])
    max_width = string.format("%.3f", defect_bbox_max_width[i])
    
    -- Draw on IM1
    DrawText3D(1, "green", x, y, 0, 15, "Dent" .. i )
    DrawText3D(1, "green", x, y - 1.5, 0, 15, "Height：" .. height)
    DrawText3D(1, "green", x, y - 3, 0, 15, "Area：" .. area)
    DrawText3D(1, "green", x, y - 4.5, 0, 15, "Max Width：" .. max_width)
end


if count == 7 then
    Jump("End")
else
    SetIntVariable("Count", count + 1)
    Jump("Start")
end

![Local Image](./picture/11.png)

6. The processing logic for the remaining slices is the same as for the first slice.