基于单光子雪崩二极管的激光雷达建模与仿真

Modeling and Simulation of LiDAR Based on Single-Photon AvalancheDiode

基于单光子雪崩二极管(SPAD)的激光雷达凭借其灵敏度高、探测距离远、集成度高等优点被广泛应用于三维感知领域。SPAD激光雷达系统中包含各种功能的子模块。研究这些子模块对激光雷达系统性能的影响有助于进一步优化系统方案,提高研发效率,降低研发成本。因此,从系统子模块的特性出发,利用时间相关单光子计数技术(TCSPC)和蒙特卡罗法建立了基于SPAD的激光雷达模型,得到了被动复位电路和主动复位电路、单事件首光子时间数字转换器(TDC)和多事件TDC对系统性能的影响。结果表明:在目标飞行时间为20 ns、环境光为50×10^(3) lx、目标反射率为10%的条件下,主动复位电路与被动复位电路的系统性能基本相当;当目标反射率增加到50%后,主动复位电路的系统性能优于被动复位电路;类似地,多事件TDC的系统性能优于单事件首光子TDC,主要表现在,与单事件首光子TDC相比,多事件TDC的噪声本底计数为均匀分布,其信号计数的峰值更易大于噪声本底计数的峰值,寻峰算法更简单,算力需求更少。仿真结果表明,为使系统性能最优化,SPAD集成芯片的后端子模块应采用主动复位电路和多事件TDC的组合架构。

The LiDAR based on single-photon avalanche diode(SPAD)is widely used in 3D perception due to its advantages of high sensitivity,long detection distance and high integration level.The LiDAR system based on SPAD contains various sub-modules,and studying the influence of different types of sub-modules on the performance of LiDAR system can help optimizing the system scheme,improving R&D(research and development)efficiency,and reducing R&D cost.Therefore,according to the feature of sub-modules,we use the time-correlated single-photon counting technology(TCSPC)and the Monte Carlo method to establish the LiDAR model based on SPAD.The effects on system performance of passive reset circuit and active reset circuit,single-event first-photon TDC(time to digital converter)and multi-event TDC are obtained.The results show that the system performance of the active reset circuit and the passive reset circuit is basically the same under the conditions of the time of fight of 20 ns,the ambient light of 50×10^(3)Ix,and the target reflectivity of 10%.After the target reflectivity increases to 50%,the system performance of the active reset circuit is better than that of the passive reset circuit.Similarly,the system performance of multi-event TDC is better than that of single-event first-photon TDC,mainly because the noise of multi-event TDC is uniformly distributed,and compared with single-event first-photon TDC,the peak value of signal count of multi-event TDC is more likely to be greater than the peak value of noise floor count,and the corresponding solution range algorithm is simpler and requires less computing power.The simulation results show that in order to optimize the system performance,the sub-module of the SPAD integrated chip should adopt the architecture of active reset circuit and multi-event TDC.