FPGA-based wireless sensor nodes for vibration monitoring system and fault diagnosis

The use of wireless sensor networks (WSN) in different applications and domains is constantly growing. In the industrial applications, especially the monitoring of rotating machinery, WSN technology is mature enough to be considered as the most appropriate alternative to traditional wired systems due to a specific constraints related to the art itself. Given the importance of this area, the sensor nodes constituting industrial wireless sensor networks must meet some exigencies such as secure data transmission, high sampling rate and synchronous data acquisition, which require such minimum level of data processing capabilities. In the present work, we developed an FPGA-based wireless sensor node for a machine vibration monitoring system and fault diagnosis. The proposed wireless node is based on Xilinx Artix-7 XC7A35T FPGA circuit, connected via a Serial Peripheral Interface (SPI) to the RF transceiver nRF24L01+ as low-cost and low-power wireless radio module. An additional AES (Advanced Encryption Standard) block is implemented as custom IP core so that the transmitted data is highly secured. A solution is proposed in order to improve the synchronization using a sink node as master to trigger a simultaneous data acquisition in the network. To validate the node, experimental tests are performed on a rotating machine test bench with unbalance fault. The measurement results showed that the designed node met the requirements for synchronous data acquisition where a minimal error of 60 ns is reached.