Virtual simulation technology is of great importance for the teleoperation of lunar rovers during the exploration phase, as well as the design of locomotion systems, performance evaluation, and control strategy verifi...Virtual simulation technology is of great importance for the teleoperation of lunar rovers during the exploration phase, as well as the design of locomotion systems, performance evaluation, and control strategy verification during the R&D phase. The currently used simulation methods for lunar rovers have several disadvantages such as poor fidelity for wheel-soil interaction mechanics, difficulty in simulating rough terrains, and high complexity making it difficult to realize mobility control in simulation systems. This paper presents an approach for the construction of a virtual simulation system that integrates the features of 3D modeling, wheel-soil interaction mechanics, dynamics analysis, mobility control, and visualization for lunar rovers. Wheel-soil interaction experiments are carried out to test the forces and moments acted on a lunar rover’s wheel by the soil with a vertical load of 80 N and slip ratios of 0, 0.03, 0.05, 0.1, 0.2, 0.3, 0.4, and 0.6. The experimental results are referenced in order to set the parameters’ values for the PAC2002 tire model of the ADAMS/Tire module. In addition, the rough lunar terrain is simulated with 3DS Max software after analyzing its characteristics, and a data-transfer program is developed with Matlab to simulate the 3D reappearance of a lunar environment in ADAMS. The 3D model of a lunar rover is developed by using Pro/E software and is then imported into ADAMS. Finally, a virtual simulation system for lunar rovers is developed. A path-following control strategy based on slip compensation for a six-wheeled lunar rover prototype is researched. The controller is implemented by using Matlab/Simulink to carry out joint simulations with ADAMS. The designed virtual lunar rover could follow the planned path on a rough terrain. This paper can also provide a reference scheme for virtual simulation and performance analysis of rovers moving on rough lunar terrains.展开更多
目的解决月面着陆器在下降过程中可能得不到足够的匹配点进行着陆区地形恢复的问题。方法基于特征边缘线梯度比例约束的明暗恢复形状(shape from shading)算法。首先以Lommel-Seeliger模型模拟月表反射情况,建立辐照度方程;然后以地形...目的解决月面着陆器在下降过程中可能得不到足够的匹配点进行着陆区地形恢复的问题。方法基于特征边缘线梯度比例约束的明暗恢复形状(shape from shading)算法。首先以Lommel-Seeliger模型模拟月表反射情况,建立辐照度方程;然后以地形特征边缘提取结果为基础,经过最小二乘拟合与表面光滑模型约束后,演化得到剩余影像点的梯度比例因子,实现对辐照度方程的正则化约束。结果经过测试得到模拟影像的平均相对恢复精度可以达到-0.199,真实影像月面可以达到0.051和0.022。结论本文算法能够有效地进行3维地形恢复,且恢复精度优于经典SFS算法中对实际地形恢复效果最好的Tsai算法。展开更多
For the concerted motion of rocker lunar rover, the pitch angle of rocker of a rocker lunar rover in uneven terrain must be calculated. According to the character of passive shape-shifting adaptive suspension of rocke...For the concerted motion of rocker lunar rover, the pitch angle of rocker of a rocker lunar rover in uneven terrain must be calculated. According to the character of passive shape-shifting adaptive suspension of rocker lunar rover, the model of rocker lunar rover and the model of terrain were both simplified. The pitch angle of rocker was calculated using forward solving, reverse solving and the method of offsetting the curve of terrain respectively. Because of the banishment of the nonlinearity of equation sets of calculation by reverse solving, the calculation of the pitch angle based on reverse solving was programmed by means of MATLAB. Simulations were carried out by means of ADAMS. The result verified the validity of the calculation based on reverse solving. It provides the theoretical foundation for motion planning and path planning of rocker lunar rover. As applications of the calculation of pitch angle of rocker, the multi-attribute decision making of path based on the concerted motion planning and the predictive control on lunar rover based on the Markov prediction model were introduced.展开更多
基金supported by National Natural Science Foundation of China (Grant No. 50975059, Grant No. 61005080)Postdoctoral Foundation of China (Grant No. 20100480994)+1 种基金Postdoctoral Foundation of Heilongjiang Province, Foundation of Chinese State Key Laboratory of Robotics and Systems (Grant No. SKLRS200801A02)College Discipline Innovation Wisdom Plan of China (111 Project, Grant No. B07018)
文摘Virtual simulation technology is of great importance for the teleoperation of lunar rovers during the exploration phase, as well as the design of locomotion systems, performance evaluation, and control strategy verification during the R&D phase. The currently used simulation methods for lunar rovers have several disadvantages such as poor fidelity for wheel-soil interaction mechanics, difficulty in simulating rough terrains, and high complexity making it difficult to realize mobility control in simulation systems. This paper presents an approach for the construction of a virtual simulation system that integrates the features of 3D modeling, wheel-soil interaction mechanics, dynamics analysis, mobility control, and visualization for lunar rovers. Wheel-soil interaction experiments are carried out to test the forces and moments acted on a lunar rover’s wheel by the soil with a vertical load of 80 N and slip ratios of 0, 0.03, 0.05, 0.1, 0.2, 0.3, 0.4, and 0.6. The experimental results are referenced in order to set the parameters’ values for the PAC2002 tire model of the ADAMS/Tire module. In addition, the rough lunar terrain is simulated with 3DS Max software after analyzing its characteristics, and a data-transfer program is developed with Matlab to simulate the 3D reappearance of a lunar environment in ADAMS. The 3D model of a lunar rover is developed by using Pro/E software and is then imported into ADAMS. Finally, a virtual simulation system for lunar rovers is developed. A path-following control strategy based on slip compensation for a six-wheeled lunar rover prototype is researched. The controller is implemented by using Matlab/Simulink to carry out joint simulations with ADAMS. The designed virtual lunar rover could follow the planned path on a rough terrain. This paper can also provide a reference scheme for virtual simulation and performance analysis of rovers moving on rough lunar terrains.
文摘目的解决月面着陆器在下降过程中可能得不到足够的匹配点进行着陆区地形恢复的问题。方法基于特征边缘线梯度比例约束的明暗恢复形状(shape from shading)算法。首先以Lommel-Seeliger模型模拟月表反射情况,建立辐照度方程;然后以地形特征边缘提取结果为基础,经过最小二乘拟合与表面光滑模型约束后,演化得到剩余影像点的梯度比例因子,实现对辐照度方程的正则化约束。结果经过测试得到模拟影像的平均相对恢复精度可以达到-0.199,真实影像月面可以达到0.051和0.022。结论本文算法能够有效地进行3维地形恢复,且恢复精度优于经典SFS算法中对实际地形恢复效果最好的Tsai算法。
基金Sponsored by the National Natural Science Foundation of China(Grant No.50375032)the 111 Project (Grant No.B07018)
文摘For the concerted motion of rocker lunar rover, the pitch angle of rocker of a rocker lunar rover in uneven terrain must be calculated. According to the character of passive shape-shifting adaptive suspension of rocker lunar rover, the model of rocker lunar rover and the model of terrain were both simplified. The pitch angle of rocker was calculated using forward solving, reverse solving and the method of offsetting the curve of terrain respectively. Because of the banishment of the nonlinearity of equation sets of calculation by reverse solving, the calculation of the pitch angle based on reverse solving was programmed by means of MATLAB. Simulations were carried out by means of ADAMS. The result verified the validity of the calculation based on reverse solving. It provides the theoretical foundation for motion planning and path planning of rocker lunar rover. As applications of the calculation of pitch angle of rocker, the multi-attribute decision making of path based on the concerted motion planning and the predictive control on lunar rover based on the Markov prediction model were introduced.
