Acceleration Anomaly Detection Method for Sensor Axle Box of Unmanned Vehicle

Detecting the anomaly acceleration of the sensor’s axle box of unmanned vehicles is very important for judging the wear condition of vehicle track and evaluating the state of the track. A capacitive accelerometer is connected with acquisition equipment to collect the information of train axle box’s acceleration change when the vehicle is running; instrument amplifier AD8250 with a digitally programmable gain is selected as system signal conversion chip to realize acceleration signal conversion; sliding variance of axle box’s acceleration of the unmanned vehicle is calculated based on sliding variance statistical analysis method, which is confirmed by time window and distance window. Fixing the width of a sliding window according to the response statistics caused by the line excitation link, the acceleration sliding variance is compared with the standard one to determine whether the acceleration is in an anomaly state. The test results show that the anomaly acceleration of the sensor axle box of the unmanned vehicle detected by the proposed method is consistent with the actual results, which provides a reliable basis for vehicle track condition assessment.

A Pipeline-TDC-Based CMOS Temperature Sensor with a 48 fJ·K2 Resolution FoM

An energy-efficient temperature sensor is important for temperature monitoring in Biomedical Internet-of-things (BIoT) applications. This article presents a time-domain temperature sensor with a pipeline time-to-digital converter (TDC). A programmable-gain time amplifier (PGTA) with high linearity and wide linear range is proposed to improve the resolution of the sensor and to reduce the chip area. The conversion time of the sensor is reduced by the fast TDC that only needs ~26 ns/conversion, which means the sensor is suitable for BIoT applications that commonly use duty cycling mode. Fabricated in a 40 nm standard CMOS technology, the sensor consumes 7.6 μA at a 0.6 V supply and achieves a resolution of 90 mK and a sensitivity of 0.62%/°C in a 1.3 μs conversion time. This translates into a resolution figure-of-merit of 48 fJ·K2. The sensor achieves an inaccuracy of 0.39 °C from −20 °C to 80 °C after two-point calibration. Duty cycling the sensor results in an even lower average power: ~18.6 nW at 10 conversions/s.