A continuous wavelet transform-based modulus maxima approach for the walk error compensation of pulsed time-of-flight laser rangefinders

Semiconductor pulsed time-of-flight (TOF) laser rangefinders (LRFs) have been the main distance measurement components equipped by many radar systems of Micro Unmanned Air Vehicles (MUAVs). A novel approach is proposed to improve the measurement accuracy of pulsed TOF LRFs. This approach adopted traditional single-threshold leading edge detection firstly, then employed continuous wavelet transform (CWT)-based local modulus maxima (LMMs) to detect singularities of emitting pulses and receiving echoes of LRFs, and obtained the compensation time with detected singularities to revise the measurement model. A series of experiments were done in a proposed pulsed TOF LRF prototype, and the measurement model is built by linear fitting. With the compensation values of various wavelets, the optimum revised measurement model is obtained. It is demonstrated that the single-shot precision of the pulsed TOF LRF achieves 195 ps (∼29 mm) with SNR = 7, and the absolute error is reduced from 9.25 to 6.32 mm. Therefore, the proposed approach can better compensate the walk error of the existing pulsed TOF LRFs and improve the performance of TOF LRFs.