因基于摇臂式月球车释放机构在月球车释放时对着陆器的倾翻力矩较大,易使着陆器倾翻而导致整个探测任务失败,所以对月球车着陆释放时着陆器稳定性的研究尤为重要。将着陆器腿不等量压缩、月面坡度、低重力环境、释放加速度等因素进行参数化处理;应用D-H坐标法得到基于各参量的支撑多边形坐标以及着陆器和月球车的位姿方程,进而建立了月球车释放过程中的零力矩点(ZMP)坐标方程和稳定性判定依据。通过实例仿真分析,一方面验证了方程的正确性,另一方面得到了各参数对着陆器稳定性的影响,进而求得着陆器不倾翻的临界月球车着陆释放速度,该速度为月球车着陆释放控制提供了理论依据。
When a lunar rover is being unloaded from the lander by a rocker-style unloading mechanism, the overturning moment acting on the lander may be so large that it can make the whole exploration mission a failure. Therefore it is very important to research on the impact of rover unloading on lander stability. Different compression extents of the lander leg and complicated conditions of the lunar surface and unloading speeds are first defined as parameters and then support polygon coordinates and the positions of the rover can be expressed as the equations of these parameters by the D-H coordinate method, and finally the zero moment point (ZMP) coordinate equation and stability criteria are found. It can be verified that the equation is correct and the influence of every parameter on lander stability and the critical instability speed are found by simulation example analysis. This study can serve as the theoretical basis for the control strategy of rover unloading.
[1] Peng J, Liu Z Y, Zhang H. Conceptual design of a lunar lander [J]. Spacecraft Engineering, 2008, 17(1): 18-23.
[2] David D, Atkinson J. The lunar precursor robotic program//Proceedings of 45th AIAA Aerospace Sciences Meeting and Exhibit. Reno, Nevada: AIAA, 2007: 1-6.
[3] 欧阳自远. 月球探测的进展与中国月球[J]. 地质科技情报, 2004, 23(4): 1-5. Ouyang Ziyuan. International lunar exploration progress and Chinese lunar exploration[J]. Geological Science and Technology Information, 2004, 23(4): 1-5. (in Chinese)
[4] Mcgebee J R, Stubbs M. Experimental validation of a landing-dynamics computer program for legged spacecraft landers . NASA-TN-D-7301, Washington: NASA, 1973.
[5] George A. Z, JR, Harold H. D. A mathematical procedure for predicting the touchdown dynamics of a soft-landing vehicle. NASA-TN-D-7045, Washington: NASA, 1971.
[6] Harold D S. Apollo experience report guidance and control system: Lunar module stabilization and control system. NASA-TN-D-8227, Washington: NASA, 1975.
[7] Masahiro N. Modeling for lunar lander by mechanical dynamics//AIAA Modeling and Simulation Technologies Conference and Exhibit. Jersey: 2005.
[8] 褚桂柏, 张熇. 月球探测器技术[M]. 北京: 中国科学技术出版社, 2007: 38-50. Chu Guibai, Zhang He. Lunar explorer technology [M]. Beijing: China Science and Technology Press, 2007: 38-50. (in Chinese)
[9] 刘焕焕. 多腿式月球探测软着陆器着陆动力学建模与仿真研究. 南昌: 南昌大学机电工程学院, 2008. Liu Huanhuan. Landing dynamic modeling and simulating analysis of mutil-legged lunar lander. Nanchang: School of Mechatronics Engineering, Nanchang University, 2008. (in Chinese)
[10] 朱汪, 杨建中. 月球着陆器软着陆机构着陆稳定性仿真分析[J]. 字航学报, 2009, 30(5): 1792-1796. Zhu Wang, Yang Jianzhong. Touchdown stability simulation of landing gear system for lunar lander[J]. Journal of Astronautics, 2009, 30(5): 1792-1796. (in Chinese)
[11] Li K, Liu R Q, Jiang S, et al. Research on rocker-style elevator with strong lunar surface adaptability[J]. Applied Mechanics and Materials, 2010, 37-38: 1076-1081.
[12] 刘荣强, 邓宗全, 李奎. 星球探测车释放用摇臂式着陆梯: 中国, ZL200810064607.0. 2009-12-16. Liu Rongqiang, Deng Zongquan, Li Kui. A roker style landing ladder for rover unloaded: China, ZL 200810064607.0. 2009-12-16. (in Chinese)
[13] 刘宇红, 张明路, 孟宪春, 等. 基于ZMP的移动机械手运动稳定性分析方法研究与仿真[J]. 河北工业大学学报, 2009, 38(2): 26-31. Liu Yuhong, Zhang Ming1u, Meng Xianchun, et al. Researching and simulation of mobile manipulator stability and compensation measurement based on ZMP[J]. Journal of Hebei University of Technology, 2009, 38(2): 26-31. (in Chinese)
[14] 俞志伟, 王立权, 韩金华. 双足机器人行走稳定性研究[J]. 哈尔滨工程大学学报, 2009, 30(11): 1285-1290. Yu Zhiwei, Wang Liquan, Han Jinhua. Walking stability in bipedal robots [J]. Journal of Harbin Engineering University, 2009, 30(11): 1285-1290. (in Chinese)
[15] 李艳杰, 钟华. 轮式仿人机器人的ZMP建模及动态稳定判据[J]. 沈阳理工大学学报, 2009, 28(1): 79-84. Li Yanjie, Zhong Hua. The ZMP modeling and the dynamic stability criterion of the wheel-based humanoid robot[J]. Transactions of Shenyang Ligong University, 2009, 28(1): 79-84. (in Chinese)
[16] 罗昌杰,邓宗全,刘荣强,等. 基于零力矩点理论的腿式着陆器着陆稳定性研究[J]. 机械工程学报, 2010, 46(9): 38-45. Luo Changjie, Deng Zongquan, Liu Rongqiang, et al. Landing stability investigation of legged-type spacecraft lander based on zero moment point theory[J]. Journal of Mechanical Engineering, 2010, 46(9): 38-45. (in Chinese)
CJA