During the manufacturing process, the final phase is usually the packaging such that the package should also contain the product’s accessories. The check for eventually missing items in the package is part of the quality control procedures and it should be carry out without opening the box. One possible solution to this task is a system based on mass measurement. This method has the advantage to be able to determine which items are eventually missing from the package.
To solve this problem, I created a simple, robotized quality control station at the Department of Control Engineering and Information Technology. The station comprises a PLC, a robot arm and a graphical display. The operation of the monitoring system also needed a balance-sheet and a driver circuit. The circuit uses comparators on the analog output signal of the balance-sheet, provides binary results and adjusts the voltage level to the digital inputs of the PLC. The PLC then transmits the received value to the robot CPU, which decides whether the package is complete or not. The robot then sorts the packages based on the measurement results. During this process, the display will show the current status of the robot and the result of the previous measurements.
The creation of the system started with the planning, simulating and building of the driver circuit. Later on I programmed the PLC and the robot itself. The last step was to memorize with the robot arm the positions over the control station and verify that the overall system is working properly.