Seeking the evidence of potential life is one essential and perpetual driving force for human planetary explorations. Compared with other technical solutions, sampling the planetary soil and returning it back to Earth for further analyzing may be the most direct method to realize this goal. Due to the fact that sample's geological stratification along the longitudinal direction completely records early stars' geological evolution, it should be better to adopt suitable sampling methods to preserve the whole sample well. Flexible tube coring (FTC) method, applying a series of hollow coring tubes into the auger to sample the subsurface regolith, can preserve sample's geological stratification without any losses, hence it has been adopted in the China Chang'e Ⅲ project. However, it should be noted that the final coring results and online drilling loads that drill tool sustained are both greatly influenced by the uncertain physical properties of lunar regolith, hence proper drilling parameters should be tuned immediately in drilling process. Otherwise, only a small amount of cored soil sample would be acquired and serious overloads drilling faults could occur correspondingly. In order to comprehend the soil flow characteristics and avoid potential drilling faults, a novel soil flow characteristics monitoring method was proposed by employing an ultrasonic sensor and an industrial camera to monitor the coring results and removal states. Experiments in one typical lunar regolith simulant revealed that penetration per revolution has great influences on drilling states and should be optimized further.
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