一种大角度范围的高精度超声波测距处理方法

A High Precision Ultrasonic Ranging Method under Misalignment of Transducer Pairs

针对移动机器人超声定位中超声收发传感器角度偏向造成的测距精度下降,本文提出了一种基于归一化波形参数特征修正的超声测距系统.传统的增益控制、可变阈值等抗起伏措施对抑制传播过程中的幅度起伏造成的测距误差效果较好,但如果传感器角度偏向使波形发生畸变,此类方法仍将造成较大误差.本文通过对传感器角度偏向造成接收信号波形畸变及测距精度下降的理论分析及实验研究,建立了超声接收信号归一化波形特征脉宽与前沿变化的关系,设计了基于单片机实现误差校正的大偏向角高精度超声波测距系统.测距实验结果表明本系统显著减小了传感器角度偏向引起的测距误差,在不同的距离上使测距精度平均提高了1.6%,同时具有成本低、使用简单、方便的特点.

To tackle the precision degradation caused by misalignment of transducer pairs in mobile robot localization,an adjustment strategy based on normalized waveform parameter is proposed to derive a high precision method for wide-field ultrasonic ranging. Presently most investigation on high precision ultrasonic ranging focused on the amplitude fluctuation induced by random air medium. Nonetheless,previous research indicated that the impact of transducer misalignment on reception signal waveform can be modeled as a low-pass filter, which will cause waveform distortion of reception signal. Thus the performance of traditional approaches to improve the ultrasonic ranging precision such as automatic gain control （AGC） or variable threshold will be seriously affected under misalignment of transducer pairs. In this paper,with theoretical analysis and experimental research on the impacts of transducer misalignment, the relationship between the rising edge and characteristic width of normalized waveform is investigated, which is used to develop an adjustment approach and design a SCM （Single Chip Microcomputer） based high precision wide-field ultrasonic ranging system. The experimental results show this system greatly improves the ranging precision under transducer misalignment, validating the effectiveness and convenience of the proposed scheme. Compared with traditional AGC type method ,it improves the ranging precision by about 1.6%.