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Research on Navigation and Control for Soft Landing on Moon

Author: DingHong
Tutor: CuiPingYuan
School: Harbin Institute of Technology
Course: Aircraft design
Keywords: Lunar soft landing Autonomous navigation and control Obstacle detection Circumvent guidance Vector measurement
CLC: V448.224
Type: Master's thesis
Year: 2008
Downloads: 83
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Abstract

With the development of the lunar exploration mission, future lunar exploration Objectives of the mission will be mainly high scientific value area with complex terrain characteristics. For high-precision soft landing can be safely completed in the rocky, crater area navigation and control systems, which requires strong autonomy, robustness, and real-time. Demand for the final landing segment safe, accurate navigation and control of lunar soft landing for a more in-depth research, the main contents include: First, the proposed obstacle detection method based on the single-frame image information. The method according to the characteristics of the landing region obstacles imaging, done by matching the corresponding shaded area with light district on the rocks, crater detection, image gray variance extraction rough area. On the basis of detection of the obstacle information, the safe landing point is selected in order to ensure a soft landing of mission success. Second, given a vector-based observations autonomous optical navigation information. The method uses the measured values ??of optical camera and laser rangefinder to build a landing point vector information relative to the lander, combined with the lander attitude information to determine the location of the lander. In order to eliminate the interference of the measurement noise, the extended Kalman filter theory to design a navigation filter. Again, proposed a Lyapunov function obstacle avoidance guidance method. The method by state function, the function of the design of the dangerous situation, and to meet the demand for both the translation process, reduce barriers to threats and accurately fixed landing using Lyapunov stability theorem design translational control law. Taking into account the Lyapunov guidance law given control over the amount of variable thrust control for using constant thrust the lateral engine lunar lander, designed PWPF (FM-width-modulated) regulator to achieve the rated thrust the equivalent variable thrust control effect. Finally, the control method proposed a vertical soft landing for the main engine with variable thrust lunar lander. The method uses a combination of nominal control and closed-loop control, and planning to ensure that the lander to reach the landing point nominal trajectory, its rate of decline, the acceleration is also zero, design closed-loop controllers generate additional amount of control to eliminate the initial deviation lander quality changes in the interference, to ensure that the lander to reach the landing site along the nominal trajectory. In this paper, on the final landing segment navigation and control method proposed mathematical simulation to verify the feasibility of the method. The simulation results show that this gives the navigation control method to achieve higher performance to meet the needs of high-precision soft landing in the danger zone.

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