Verification Project of Wireless Communication Technologies to Accelerate Factory IoT

Fig. 1. Various wireless environment evaluations and wireless communication tests carried out in a number of operating factories. 920MHz, 2.4GHz, 5GHz, and 60GHz frequency bands were used.

Fig. 2. Wireless environment evaluation conducted in factories.
Categorized by factory size, whether or not residential area is nearby, existence of shielding structures in factories, existence of facility noise, and stages of using wireless environments (Unwire Stage)

Fig. 3. Relationships among wireless communication usage and communication requirements, and frequencies/wireless standards.
In a factory, data size, data production frequency and node numbers are different in each system. Because of that, the frequency and wireless standard used are different depending on the system functions needed. It is expected to use higher frequency bands such as 60 GHz bands for systems which use a large amount of data (e.g. imaging inspection equipment). The 5 GHz and 2.4 GHz bands are used for sending control programs and/or mobile device control of systems in which data sizes and data producing frequencies are moderate. The 920 MHz and relatively low frequency bands are used for applications which need power saving (e.g. environment sensing).

Fig. 4. Permissible delay time for wireless usage categorized by control, quality, management, display, and safety.
Wireless communication systems used in factories have usually either relatively short permissible delay time (shorter than 100 milliseconds) for safety or control reasons or long permissible delay time (longer than 100 milliseconds). Most applications are required to have the permissible delay time between 10 milliseconds and 10 seconds. The first targeted delay time in this project is also within this range.

Fig. 5. Analogy for a communication situation improved by wireless stabilization. Since each existing application (e.g. existing automated conveyer system, sensor system, or assembly system using wireless torque wrench) uses its own frequency and timing to communicate, they interfere with each other and hence cause degradation of communication quality. Therefore, by coordinating those communications for inter and intra applications, the communication quality can be improved and applications and manufacturing equipment can function stably.

Fig. 6. Software configuration using wireless communication stabilization technology.
By unifying the methods of information exchange in the software applications, the software configuration is not dependent on the physical layer. We defined the required specification based on the studied 6 categories (control, quality, management, display, safety and others) in order to add this function to existing applications (existing automated conveyer systems, sensor systems or assembly systems using wireless torque wrenches).
The software configuration component added this time has application data abstraction function, wireless environment monitoring function and wireless routing function, and can comply with existing radio communication standards.
In the future, if another application in one of the above categories or a new category needs to be added, a different common information exchange scheme can also be added.