Abstract: Aimed at the problem that the synchronous error would accumulate with time in mechanical vibration acquisition using wireless sensor networks, according to the mechanism analysis of accumulated synchronous error, an accumulated synchronous error control method based on synchronous information tracking method is presented. Hardware layer of acquisition node is employed to capture the synchronous information to avoid hysteresis caused by task preemption; Crystal oscillator frequency offset estimate method based on Kalman filter is researched to improve the estimate accuracy. A feedback control system is built to feedback and compensate the synchronous error dynamically to avoid synchronous error accumulation. An embedded multitask priority management firmware is designed to guarantee the real-time performance of sampling task and accumulate synchronous error control task in mechanical vibration acquisition with high sampling rate. Experiments show that the synchronous error is kept within 0.6 us in 30 s with the sampling rate up to 51.2 kHz, and the maximum synchronous error does not exceed 3% of the sampling period, which can meet the requirement of synchronous acquisition in mechanical vibration monitoring.

Key words: accumulated error control, mechanical vibration monitoring, synchronous acquisition, wireless sensor networks