The automation of production processes is steadily growing at a high rate. As part of this phenomenon, the industrial robots are applied in an increasing number of production phases to operate both easy tasks and complex pick & place movements.
Companies transport and supply the manufactured goods in packages, comprising several components necessary for the user. For controlling the completeness of packages, the most common and efficient way is to measure their weight as mass produced components will likely to show low variation in their individual mass. Such strategy is applied for instance in TV set manufacturing factories where the package comprises a support, user manuals and a remote control in addition to the TV set itself. The aim of my thesis is the design and elaboration of a prototype weight controlling robotic cell in which a precision scale will be interfaced to a MELFA robot.
The first objective of my work was to establish the MODBUS based communication of the Excell precision scale with the Melsec PLC which shares part of its device memory with the robot CPU of an industrial Mitsubishi robotic arm. After the careful examination of available options, I chose the communication via computer for the data transmission. The data is visualized on a touchscreen Human Machine Interface (HMI) of the robot cell. The task of the robotic arm is to move the packages between the storage compartments and the scale. The target position of each package depends on the correctness of its measured weight. The last part of the task was to design an ergonomic HMI using the touchscreen. Indicators inform the user if the package passes and the missing or extra items are also displayed based on the measurements. My thesis provides detailed description of the implementation of each task.
I used multiple development environments: the communication is realized using LabVIEW, the program of the robotic arm was written in the MELFA Basic V programming language and the MELSOFT development environment family (IQ-Works) was used to test the robot program to adjust the block for the PLC and to design the interactive screens of the HMI.