Research On Location Of Martian Methane Plume Source Based On Active Olfactory Method

After years of research on Mars exploration,Mars has been confirmed to be a planet with a plume of methane,which has great research value.However,there is very little prior knowledge about the coordinates of the Martian methane plume vent.Therefore,locating the plume source coordinates during the descent of the probe will become an important research direction for future Mars exploration.On the basis of the active olfactory location method,the paper studies the source point location of the methane plume in the Martian time-invariant wind field and proposes the source point coordinate estimation method found on sequence Monte Carlo and the plume environment search method based on logarithmic spiral.The paper studies the existing active olfactory localization methods and analyzes the feasibility of the active olfactory localization method in locating the source point of the methane plume.Furthermore,starting from the negative likelihood and over-fitting caused by the traditional active olfactory localization method,a probabilistic model for the location of the source point of the methane plume is established,and a probability model of the observation event of the detector is carried out.On the basis of these two probability models,the paper recalculates the observation likelihood function to solve the negative likelihood problem caused by traditional methods and finally summarizes the problem of locating the source point of the Martian methane plume as the problem of source point coordinate estimation and the problem of plume environment exploration.For the problem of plume source point estimation,this paper studies the method of methane plume source point coordinate estimation based on sequence Monte Carlo.The particle degradation problem is controlled by the system resampling method to ensure that the weights of the examples can be iteratively updated normally.Through the introduction of the residual degradation method,the variance of the observation likelihood function is reduced to further improve the positioning accuracy and solve the fitting problems caused by the traditional methods.For fitting problems,the algorithm can converge at the plume source even if the prior estimation is biased,and the comparative experiments prove the effect of the learning rate.For the search problem of plume environment,this paper studies the method of searching plume environment based on logarithmic spiral.The plume environment is searched by using the characteristics of the large convergence of the logarithmic spiral search area,and the simulation experiment is carried out in combination with the plume source point estimation method based on sequence Monte Carlo.During the descent process,the detector uses a logarithmic spiral methods to search the plume environment and estimates the source point coordinates through the sequential Monte Carlo method.Experiments are carried out under different prior distributions to prove the effectiveness of the method.This paper studies the Mars plume source location method that allows the probe to actively locate the plume source coordinates during the descent process,and overcomes the influence of a priori guessing deviation,which has certain significance for Mars plume detection.