US 12,487,341 B2
Methods and systems for lidar walk error correction
Zhijie Ma, Shenzhen (CN); Chao Zhang, Shenzhen (CN); and Kai Zang, Shenzhen (CN)
Assigned to SHENZHEN ADAPS PHOTONICS TECHNOLOGY CO., LTD., Shenzhen (CN)
Filed by SHENZHEN ADAPS PHOTONICS TECHNOLOGY CO., LTD., Shenzhen (CN)
Filed on Jan. 25, 2022, as Appl. No. 17/584,027.
Claims priority of application No. 202110098686.2 (CN), filed on Jan. 25, 2021.
Prior Publication US 2022/0236386 A1, Jul. 28, 2022
Int. Cl. G01S 7/4865 (2020.01); G01S 7/4861 (2020.01); G01S 17/10 (2020.01); H04N 25/705 (2023.01)
CPC G01S 7/4865 (2013.01) [G01S 7/4861 (2013.01); G01S 17/10 (2013.01); H04N 25/705 (2023.01)] 20 Claims
OG exemplary drawing
 
1. A method for range determination, the method comprising:
transmitting, by a transmitting end, a pulsed laser at a first time, the pulsed laser being characterized by an initial total rise time between a pulse starting point and a pulse peak;
receiving an optical signal reflected by a target object;
converting the received optical signal into an analog electrical signal by a pixel circuit;
converting the analog electrical signal into histogram data using a time-to-digital converter (TDC), the histogram data comprising n intensity values corresponding to n time bins;
storing the histogram data in a memory module;
calculating a preliminary peak location using the histogram data, the preliminary peak location being associated with a target object distance, the preliminary peak location being associated with a highest peak intensity value of and a corresponding time bin location of the histogram data;
comparing the preliminary peak location to a threshold value, the threshold value being associated with a threshold distance;
if the preliminary peak location is less than the threshold value, determining the pulse starting point by locating m consecutive rising intensity values, and calculating a corrected peak location by adding a total rise time value, m being at least three; and
calculating a time of flight (TOF) value using the first time and a second time, the second time being based on the corrected peak location or the preliminary peak location; and
determining the target object distance.