ZIGBEE NETWORKS FOR DATA COMMUNICATION IN MACHINE TOOLS

The widespread application of wireless communication in industrial environment is currently limited due to considerable high requirements including real-time capability, transmission reliability and energy consumption. In the area of production engineering further optimization of machining processes requires the knowledge of a variety of process variables that can be captured with the aid of appropriate sensors. Within the machine tool sector progressively modular designs are applied by machine tool manufacturers. This ideally allows the integration of distributed sensor systems within different machine tool modules particularly for process monitoring purposes. Therefore a combination of wireless communication systems and inductive energy transmission systems enables to realize the energy transfer as well as the data communication between the sensors and the machine tool control. Additionally it offers the potential of abandoning connectors and reducing expensive cable laying.  Since ZigBee already proved its reliability and robustness in the context of a data transmission in industrial environment this paper presents a cost efficient realization of a ZigBee piconet as the basis of a wireless data communication within machine tools with modular structure. The developed ZigBee-Modules enable the acquisition of measured data of connected sensors as well as the reception of control data for linked actuators. Finally, the paper presents three communication algorithms suitable for different requirements for an application in machine tools. For this purpose an analysis of the data transfer cycle time subject to the number of ZigBee modules participating in the data transfer and the applied algorithm is introduced.