An inspection system that uses a robot-mounted camera is providing a unique approach to the examination, integrity and traceability of mass manufactured assemblies, according to system developers Goldlogic Control Systems (GCS) of Worsley, Manchester.
Eliminating the fallibility of human inspection and the inefficiencies of static inspection systems, the GCS system takes advantage of the six-axis mobility and accuracy of an ABB robot to position a camera at various pre-determined positions to examine key features of an assembly.
The manoeuvrability and repeatability of the ABB robot, and the accuracy of its programming system, mean that the camera can be positioned at the optimum angle for illuminating and photographing the target - a vital factor when inspecting welds, for example, and an impossible task with a static camera system.
Fully supportable standard OEM equipment is specified for the system including a ceiling/wall/floor mounted ABB IRB 140 or floor mounted IRB 2400 robot, Siemens VS 723 camera, and Siemens S7 programmable logic control (PLC), which communicates with both camera and robot over a Profibus network. A further feature of the system is a PC-based archiving software program developed by GCS.
“Though we use standard equipment throughout, we are the first company to have brought everything together within the one system. When linked to our own specially developed data acquisition software, the result is an innovative inspection system,” said Iain Smith, who co-founded GCS in 1989.
Using the new system, a typical examination of a car seat frame assembly could incorporate, on average, 20 inspections. These could include inspection of specific key welds for integrity, dimensional check of washers to ensure the correct piece part is installed, correct installation of rivets and the examination of threads for weld spatter. Each cycle is not only very fast, when compared with visual inspection methods - but also very accurate, according to GCS.
GCS’ bespoke software communicates with camera, PLC and robot, uploading a 300 KByte bitmap image to the PC hard drive at each inspection position. Every image can be stored, or optionally, only ‘failed’ images uploaded, depending upon requirements. The uploaded image can be readily identified by a file number linked to the part number or bar coding of the product. If necessary, the stored data can then be transferred by Ethernet to a central server - though a standard industrial PC with a 160 GByte drive would take about 10 years to fill when in virtually constant use.
Any number and virtually any type of visual inspection can be included within the cycle - by simply amending the robot and PLC programs. In addition, a modified part can be rapidly brought on-line; just by ‘teaching’ the robot and PLC the new coordinates. Similarly, when new assemblies are introduced, the robot-based inspection system can be quickly and economically re-programmed, unlike static inspection systems, which may well have to be scrapped.
Although the system was initially developed for the automotive industry it has viable applications within the aerospace, pharmaceutical, white goods and the electronics industries – indeed anywhere that traceability is a requirement,” said Smith.