Research On Mission Planning Method Of Mars Rover Under Complex Constraints

With the gradual development of human deep space exploration activities,Mars,as a planet in the solar system with similar natural environment and relatively close distance to the earth,has become the preferred target for human planetary exploration.As the main carrier of Mars exploration missions,improving its working ability in unknown and complex environments has always been a hot issue in engineering and academic research.In this paper,combined with China’s first Mars exploration mission(Tianwen-1),the mission planning method of the "Zhurong" Mars rover is studied.Firstly,the complex environment of the Martian surface is modeled,and on this basis,the mission-level path planning and behavior pattern planning are analyzed.Finally,the planning effect is verified by simulation analysis and on-orbit application.In order to improve the intelligent level of the rover,the research on the method of autonomous scientific detection is carried out to improve the efficiency of man-machine cooperation and expand the amount of scientific detection data through autonomous scientific target recognition and trajectory tracking control.Based on the extensive investigation of the inspector and mission planning technology of domestic and foreign rovers,the mission requirements of the rover working on the Martian surface are analyzed,and a hierarchical rover mission planning architecture based on humancomputer interaction is proposed.Considering the factors of dynamic time,static terrain,illumination and energy,the functional relationship between the rover relative to the sun,the earth and the orbiter is obtained.On this basis,mission planning is divided into functional modules such as path planning,behavior pattern planning and autonomous target recognition,and the correlation and difference between each part are analyzed.According to the characteristics of Mars exploration,the effects of various topographic factors,solar illumination and communication conditions on the mission-level path planning of the rover are analyzed.A map of the driving environment on the Martian surface is established with terrain risk,energy risk and communication condition risk as the core,and the mission-level planning path that meets the needs of scientific exploration is obtained by searching the artificial cost points on the risk map.The state space of six conventional behavior patterns of the rover is established,and the forward chain search is carried out in the state space to get the behavior sequence that meets the conditions of energy,thermal control and resource storage.Through simulation and on-orbit application,it is verified that the planning results can meet the working requirements of the rover.The mission-level path planning and behavior pattern planning play a good role in supporting the work of the rover in orbit.In order to meet the autonomous ability of the rover in the future,a network structure for self-identification of rocks is proposed.Specifically,the improved U-Net network structure is obtained by combining the Criss-Cross attention(CCA)module and the Efficient Channel Attention(ECA)idea.The image data collected by the "Zhurong" rover in orbit are marked and processed to obtain the Mars in-orbit rock data set.Compared with other rock segmentation networks,the accuracy of the designed image segmentation network is improved to a certain extent.Considering the complex environment on the surface of Mars and the objective requirements of the rover to carry out scientific exploration,the blind movement mode,most commonly used by the rover is taken as the research condition.A trajectory tracking controller considering nonholonomic constraints is designed to improve the driving performance of the rover.Based on the planning module,the trajectory which is convenient for the rover to track accurately is planned,and the trajectory is tracked by the improved model predictive control,finally,the tracking performance of several kinds of the rover in orbit is simulated and analyzed,which can meet the requirements of mobile safety performance and scientific detection accuracy of the rover.The research results of this paper provide a basic design scheme for the overall mission planning of the rover,and the research on independent scientific exploration has a certain reference value for the follow-up rover exploration mission in our country.