Existing piezoelectric vibration energy harvesting circuits require auxiliary power for the switch control module and are difficult to adapt to broadband piezoelectric vibration energy harvesters. This paper proposes a self-powered and low-power enhanced double synchronized switch harvesting (EDSSH) circuit. The proposed circuit consists of a low-power follow-up switch control circuit, reverse feedback blocking-up circuit, synchronous electric charge extraction circuit and buck-boost circuit. The EDSSH circuit can automatically adapt to the sinusoidal voltage signal with the frequency of 1 to 312.5 Hz that is output by the piezoelectric vibration energy harvester. The switch control circuit of the EDSSH circuit works intermittently for a very short time near the power extreme point and consumes a low amount of electric energy. The reverse feedback blocking-up circuit of the EDSSH circuit can keep the transmission efficiency at the optimal value. By using a charging capacitor of 1 mF, the charging efficiency of the proposed EDSSH circuit is 1.51 times that of the DSSH circuit.

Multi-sensor systems require precise time synchronization for accurate data fusion. However, currently prevalent software time synchronization methods often rely on clocks provided by the Global Navigation Satellite System (GNSS), which may not offer high accuracy and can be easily affected by issues with GNSS signals. To address this limitation, this study introduces a novel laser pulse-driven time synchronization (LPTS) method in our custom-developed Light Detecting and Ranging (LiDAR) system. The LPTS method uses electrical pulses, synchronized with laser beams as the time synchronization source, driving the Micro-Controller Unit (MCU) timer within the control system to count with a timing accuracy of 0.1 $\mathsf{\mu }$s and to timestamp the data from the Positioning and Orientation System (POS) unit or laser scanner unit. By employing interpolation techniques, the POS and laser scanner data are precisely synchronized with laser pulses, ensuring strict correlation through their timestamps. In this article, the working principles and experimental methods of both traditional time synchronization (TRTS) and LPTS methods are discussed. We have implemented both methods on experimental platforms, and the results demonstrate that the LPTS method circumvents the dependency on external time references for inter-sensor alignment and minimizes the impact of laser jitter stemming from third-party time references, without requiring additional hardware. Moreover, it elevates the internal time synchronization resolution to 0.1 $\mathsf{\mu }$s and significantly improves relative timing precision.