Research On Monocular Vision Pose Measurement Technology In Low-gravity Simulation Of Mars Rover

The Mars Rover is an important detector for the detection of Mars.It is particularly important to conduct experiments of the dynamic properties in a simulated low-gravity environment.The suspension method is an efficient and convenient method in the ground simulation of low-gravity environment.The suspension method requires advance knowledge of the position and orientation information of the measured object movement in order to accurately track and gravity compensation.How to obtain real-time and accurate position and orientation information of the measured object movement has always been the research difficulty and hot spot in the suspension method.The subject originated from "Mars Rover's Moving Surface Test System" and studied the pose and orientation measuring system in the suspension method.It has important theoretical significance and application value.The main function of the visual pose measuring system is to measure the position and orientation information of the rover in real time.This paper first analyzes the research status of the existing pose measurement methods in the low-gravity environment simulation,and compares the advantages and disadvantages of each methods.The index requirements of the project determined the use of monocular vision pose measurement methods,and the overall design of the measurement system is given.On the basis of the overall design,a feature point centroid localization method based on Gaussian function region fitting combined with bilinear interpolation is introduced.After the motion visual analysis,the P3 P algorithm is used to measure pose information;Combined with the overall layout of the low-gravity environment simulation system of Mars Rover establishs a mathematical model for the measurement coordinate system transformation,which can realize the real-time calculation of the position of the suspended point of the rover.The design of the rotating pan-tilt mechanism eliminates the visual impact of the sling when the measured object rotates 360° continuously in the traditional suspension method.In order to satisfy the measurement system,hardware and software systems were designed in detail,including the extraction of image feature points and the design of communication modules.Taking into account the requirements of system reliability,the design of master-slave systems for mutual backup was adopted and analyzed in detail possible system failures and corresponding exception handling measures.Then the camera internal reference,optical axis verticality,and pan-tilt center shift are calibrated.Image feature point positioning stability,static pose measurement accuracy,and dynamic pose measurement are performed on an experimental platform.Accuracy test experiments verify the feasibility of the system and meet the technical specifications.Finally,this system was applied to the low-gravity simulation experiment of the rover.The tracking error satisfies the technical indicators and the simulation experiment was completed safely and effectively.