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Description
Light Detection and Ranging (LiDAR) is a key enabling technology for autonomous navigation and obstacle avoidance in lunar rovers, where Time-of-Flight (ToF) LiDAR provides centimeter-level ranging accuracy by measuring the temporal delay between emitted laser pulses and their reflected echoes. However, the lunar environment poses severe challenges, including low surface reflectivity, intense solar background radiation due to the absence of an atmosphere, and strict constraints on power consumption and thermal dissipation, resulting in very low echo signal-to-noise ratios (SNR). To address these challenges, this work presents a weak-signal LiDAR system that employs an avalanche photodiode (APD) for echo detection and an FPGA-based backend implementing long-time coherent integration (LTCI) for signal processing. The proposed method achieves centimeter-level ranging accuracy even when the echo SNR is below unity. In addition, by dynamically adjusting the APD bias voltage, the system maintains a wide dynamic range for strong return signals, achieving an overall dynamic range of up to 60 dB.
A prototype system has been realized, integrating a mode-locked laser, an avalanche photodiode (APD) detector, a 1 GSa/s analog-to-digital converter (ADC), and an FPGA-based digital backend. All signal processing is executed on the FPGA, facilitating precise timing extraction and achieving centimeter-level ranging accuracy. The proposed architecture provides a robust and energy-efficient framework for high-precision LiDAR operation specifically designed for lunar rovers, addressing the extreme low-SNR conditions of the lunar surface environment.
| Minioral | Yes |
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| IEEE Member | No |
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