Error Measurement And Synthesis Of Lunar Soft Landing Movement Simulation System

Lunar soft landing movement simulation system consists of two parts: a lunar sand table display and a six-degree-of-freedom movement simulation system. The lunar sand table display is mainly used for simulating lunar surface. The six-degree-of-freedom movement simulation system is mainly used to simulate lander's flight and landing process on the surface of the moon. The whole simulation system is mainly used to simulate the lunar soft lander landing softly on the lunar surface. The accuracy of the six-degree-of-freedom movement simulation system directly affects the accuracy of soft lander's landing accuracy. How each error could affect the overall position and attitude? How to measure each error? This paper is carried out on these issues.Firstly,based on the knowledge of the topology and error propagation, the error model of the six-degree-of-freedom movement simulation system was established. This error model includes all the 54 errors, which serves as the foundation for the subsequent content. Error modeling process is as follows: Firstly, establish the error matrix of the adjacent body; Then, using the knowledge of error propagation, establish the error matrix of the terminal coordinate system relative to the reference coordinate system.One error is the perpendicularity error among the 3-D guideways. Firstly measure the levelness of the X guideway and Y guideway, and two-dimensional perpendicularity error of Z guideway against the horizontal plane; Then obtain X-Z and Y-Z perpendicularity error by calculation; Then Fix the theodolite on the Z guideway, and fix a target in front of X guideway and Y guideway respectively. Perpendicularity error of X-Y can be obtained through reasonable calculation and measurement. The paper also analyzes the accuracy of the corresponding results.Measurement method of the parallelism errors between the three axes of the three-axis turntable and three translational guideways is as follows: Firstly, measure the perpendicularity error between the outer axis of the turntable and the horizontal plane; Then measure the parallelism error between the inner axis of the turntable and the X guideway; Finally, obtain the parallelism error between the central axis of the turntable and the Y guideway by calculation. The paper also analyzes the accuracy of the corresponding results.Finally, based on the error model, the errors for the equipment according to the given requirements of the total error were distributed. Firstly, distribute the errors based on identical tolerance grade. However, this allocation method has disadvantages. Then, distribute the errors based on the principle of minimum consumption. This principle of distribution is consistent with the actual situation. The paper also offers the distribution results respectively. In the end, the compensated equipment's accuracy is acquired by measuring, which is compared with the uncompensated equipment's accuracy. Finally, the compensated accuracy degree of the equipment is acquired, and this has an important guiding effect on error compensation in the future.