Mechanism Analysis And Parameter Optimization On Suspension For Lunar Rover

The moon is the only satellite of the earth, as well as the latest planet from the earth. It is significant to explore the moon not only in science, technology, economic, military, politics, but also in other fields.In 1959, the humanity realized the moon exploration and closely observed the moon. From 1959 to 1976, the whole world started a climax of moon exploration. After the quiet period of nearly 18 years, from 1994, the humanity began to explore the moon again. Many countries were all positively developing the key technologies of the lunar rover.Early in 1994 our country had researched the necessity and feasibility on the moon exploration. After more than 10 years, we start the moon exploration project again, and we will launch a satellite which is called"Chang'e No.1"to complete the first phase of the moon exploration project. The first prototype rover of China is showed in the Sixth Aerospace Exhibition of Zhuhai. Therefore, some of research institutes and universities are actively engaged in related areas of the lunar rover. China expects to send a lunar rover to the moon to implement the menology exploration in 2012.The suspension is the important component of the lunar rover locomotion system. As it has the direct and indirect influences to smoothness and stability of the locomotion system, the design of the suspension system becomes the topics of the lunar rover researches.The design and analysis of the lunar rover locomotion system is extremely important. It is useful to improve the lunar rover locomotion system. At present, the analysis on the lunar rover is only about kinematics, statics and dynamics, and the mechanism analysis on the lunar rover is little. According to the issue demand of the Chinese Space Technology Research Institute, this article researches on the mechanism analysis of the suspension which is one of the most important components of lunar rover locomotion system. It will provide theoretical guidance for the lunar rover researches. It is of great realistic significance.This article analyses three aspects about the positive and negative quadrilateral suspension used in the lunar rover which is developed by Jilin University Intelligent Vehicle Group. After analysis the structure of the suspension is optimized. And then the new structure would be simulated and analyzed.Firstly this article simply summarizes the suspension system——the positive and negative quadrilateral suspension system, which would be analyzed in this article.This article establishes the statics equations when the lunar rover is still or moving with even speed on the horizon, analyzes the forces ground acting to three wheels and the forces between two pivot points of the suspension linkages, and compares the forces acting to the pivot points of the Rocker-Bogie suspension linkages. The result shows the forces acting between the linkages of the positive and negative quadrilateral suspension are larger. The forces ground acting to three wheels are not even. The torque of the linkages is smaller. The forces of the Rocker-Bogie suspension are the opposite to it.This article analyzes the ability of adapting terrain between the positive and negative quadrilateral suspension and the Rocker-Bogie suspension. In the circumstances that the six wheels all touch the ground, the ability of adapting terrain is estimated by the curvature changes of circle which is formed by three points. The three points are the centers of front, middle, and rear wheels. When the suspension is moving, the centers are moving and the curvature is changed. The analysis shows that the changing range of the positive and negative quadrilateral suspension is larger than the Rocker-Bogie suspension. Therefore, the ability of adapting terrain of the positive and negative quadrilateral suspension is better. And the ability of crossing is also better. And this article analyzes the ability of adapting terrain from the mechanism aspect.This article analyzes the velocity of three-wheel centers while climbing up the obstacles. That is the moving speed of wheels. And then based on the speed and in accordance with the basic principles of the Anti-slip Regulation System (ASR) of Driving Wheel, instantaneous rotating speeds of three wheels are obtained. Depending on the instantaneous rotating speeds, it is useful to control the speeds of the wheels, prevent the wheels sliding, avoid towing from every wheel, and minimize the energy consumption.This article proposes a new type of suspension——the quadrilateral suspension. The structure of quadrilateral suspension is simpler than positive and negative quadrilateral suspension. Then the lunar rover model with the new type of suspension is established based on ADAMS. In order to compare and analyze, the lunar rover model with the Rocker-Bogie suspension is also established based on ADAMS. The two models have the same sizes,the same qualities, and the same parameters. The two models compare six aspects: ability of equally loading weight to every wheel; ability of climbing up the obstacles; ability of climbing up the slope; stability while crossing; ability of resisting overturning; the forces acting to the pivot points. Among the six aspects, the quadrilateral suspension lunar rover is inferior to the Rocker-Bogie suspension lunar rover on only four items and superior or equal on other nine items. The test results indicate that the structure of quadrilateral suspension is simple and the characteristic is excellent. The proposed new type of suspension would provide valuable technical support to the moon exploration in the future.