For particle filtering tracking method, particle choosing was random to some degree according to the dynamics equation, which may cause inaccurate tracking results. To compensate, an improved particle filtering tracking method was presented. A moving vehicle was detected by redundant discrete wavelet transforms method (RDWT), and then the key points were obtained by scale invariant feature transform. The matching key points in the follow-up frames obtained by SIFT method were used as the initial particles to improve the tracking performance. Experimental results show that more particles centralize in the region of motion area by the presented method than traditional particle filtering, and tracking results of moving vehicles are more accurate; the run-time is only 0.15s more than traditional method, indicating that it has a certain actual application prospect.

In order to enhance the sensitivity improvement of crack meter in ruins rescue site, this paper proposes a novel crack meter with a V-shape structure. The mathematical analysis showed that there is a negative correlation between sensitivity of proposed crack and angle of V-shape structure. The finite element analysis using the ANSYS Workbench illustrates that sensitivity of proposed crack meter has rapid reduce with angle of V-shape structure of 14°–28°. Experimental findings show that the proposed V-shape structure crack meter has a higher sensitivity than the traditional one. With 14° V-shape structure crack meter, the sensitivity was enhanced to 1.16 mV/(mm/V), with an increase of 2.3 times over the traditional crack meter sensitivity of 0.35 mV/(mm/V).

The square-root unscented Kalman filter (SRUKF) is applied to identify the shape parameters of an ultrasonic echo envelope. The SRUKF has better stability than the normal unscented Kalman filter (UKF) because the square-root of the error covariance matrix used in the SRUKF guarantees positive semidefiniteness. Considering the effect of the initial state on the convergence speed of filters, the multi-SRUKF is used to estimate the time-of-flight (TOF). Each SRUKF has a different initial state. The result estimated in a limited time with minimum mean square error is finally adopted. Simulation experiments for various couples of shape parameters and signal-to-noise ratios validate the improvement in the TOF accuracy. Real experiments using the echo signals of a SensComp 600 ultrasonic transducer show that the relative means and standard deviations of the TOF error obtained using the multi-SRUKF method are less than 0.2% and 0.15%, respectively.

Ultrasonic crosstalk is one of the main causes of false distance measurements that reduce the work efficiency of sonar sensors in mobile robots. To enhance the real-time performance of sonar systems, chaotic pulse position-width modulation (CPPWM) sequences are proposed to construct short digital transmission sequences to trigger ultrasonic transducers. Thanks to their properties of sharp autocorrelation and flat crosscorrelation, chaotic series are used to modulate both pulse position and width. To obtain the better echo correlation properties and the larger echo energy, the Non-dominated Sorting Genetic Algorithm-II (NSGA-II) is adopted to optimize the pulse periods and pulse duty ratio. Real experiments using Polaroid 600 series instrument-grade electrostatic transducers validate the suitability of the proposed method.

The crosstalk in multichannel simultaneously triggered ultrasonic sensors of ultrasonic ranging system may cause false measurement. This paper presents pseudorandom digital modulation excitation sequences for multichannel ultrasonic sensors to avoid crosstalk. To make full use of bandwidth of the ultrasonic sensors, the parameters of the pseudorandom digital modulation methods are configured. A genetic algorithm is applied to optimize the pseudorandom m sequences to obtain the best echo correlation characteristics (i.e., sharpest autocorrelation and flattest cross-correlation). The polarity correlation algorithm in the receiving circuit is implemented by Field Programmable Gate Array. Real experiments have been conducted using ultrasonic ranging system that consists of eight-channel SensComp 600 series instrument-grade electrostatic sensors excited with 2 ms optimized pseudorandom digital modulation sequences. Experimental results shows that the optimized pseudorandom BFSK sequence , which can make the eight-channel ultrasonic ranging system work together without crosstalk and has a maximal 4.1 cm absolute error, has the best performance of all the pseudorandom digital modulation sequences