Machine Vision Embedded System with a laser profiler to detect quality defects in metallic sheet
Houston, Tx. A machine vision system with the use of a laser profiler to detect defects in metallic sheet was developed and implemented for a group of vision specialists by TESIS US.
The system is able to detect pits (hits), islands (metal dot) and scratches in the of the minimal size of 0.02 inches with a 200 ft/min speed line, the profiler has a configuration with small exposure time to avoid noise reflection and a frame rate of 1700 Hz.
An important challenge was reducing the noise generated by the movement of the material on the line, noise was generated by the mechanical condition of the line. With the use of software filters, we avoid the possible false positives for these circumstances.
The application with the use of an external encoder is able to synchronize with the speed of the production line and to get the footage to indicate the position (on distance) of each defect found. This information is used after by the operator to check the specific areas where defects were found and also the info is used as part of the product traceability.
The architecture of this design consists of a pc-embedded system, the profiler is connected directly to an industrial pc by ethernet cable transmitting all raw data information acquired. The information is processed in real-time in a system developed on Visual Studio, the result of the inspection on the case that a possible defect will be found is send to the PLC (programmable Logic Controller).
With the implementation of this system, an important reduction in the rejected material for quality issues is reduced. Also, with this automation system, the cycle time is optimized because the human validation is not required.
By Efrain Hernandez
Technical Project Manager. TESIS IT & Automation