根据塔机防碰撞系统远距离障碍物检测需要,针对远距离超声目标检测时,传统数字滤波对回波消噪后,回波峰值位置有延迟以及远距离信噪比较低,影响目标的检测和测距准确度.提出利用小波改进的阈值函数消噪方法进行回波消噪.仿真和实验结果表明:基于改进阈值的超声回波消噪方法使回波峰值位置无延迟,可以明显提高信噪比,其去噪效果优于传统的数字滤波和小波的软、硬阈值消噪方法,适用于远距离超声测量和目标有效检测.
According to the need of long-range obstacles detection in tower crane anti-collision system and for long-range ultrasonic target detection, after echo denosing by traditional digital filtering, there are delay of echo peak position and low signal to noise ratio (SNR) of long-range ultrasonic. These factors affect the accuracy of distance measurement and the target detection. Improved wave- let threshold function denoising method is proposed for echo denoising. Simulation and experimental results show that ultrasonic echo denoising based on improved threshold method makes ultrasonic echo peak position without delay, and can significantly improve the SNR. Its denoising effect is better than the traditional digital filtering and the wavelet soft and hard threshold denoising methods. This method is suitable for long-range ultrasonic measurement and effective detection of target.