Study Of The Influence Of Traction On Stability Of The Two-degree Of Freedom Wheeled Robot With Articulated Body

According to the robot's organizational characteristic and environmental characteristic, the terrain through which the robot passes can be divided into the inclusive terrain and the non-inclusive terrain. The inclusive terrain refers to the terrain that the robot can pass through smoothly by coordinating its own posture, but the non-inclusive terrain refers to the terrain that no matter the robot does adjust its own posture, it is unable to pass through. In this paper, gyratory degree of front and behind bodies is added to two-degree of freedom wheeled robot with articulated body, and via which when the robot encounter the non-inclusive terrain, it can adapt the strange terrain by coordinating its own posture, but it do not fall like the caterpillar type robot does, also is not be lifted and failed like the ordinary automobile. Thus the robot has strong cross-country ability and simple structure. In addition, the wheeled robot also has the flexible and quick automotive performance and the modular working device, so it can own some functions such as the rock drilling, the loading, the bulldozing and the grabbing things and so on. It is the high-tech equipment which is used in some field and dangerous activities under the complex condition like the rescue and relief work, dredging paths, prospecting minerals and so on.This wheeled robot has the original articulated body with two-degree of freedom, the full-time four-wheel drive, the articulated power steering, the modular multi-purpose working device. The travel and working device of complete machine use the remote control operation, and complete machine can depend upon the body's articulated deformation to adapt the ground condition automatically, and have the greatly strong obstacle ability. Moreover, it uses the articulated power steering to obtain the smaller turning radius and the bigger steering torque, so it has very strong automotive performance.When the wheeled robot moves on the ground, because of many complex factors consisting of traction, the interaction of various forces form a complex spatial force system at the point of mass center, the interaction between them influence the working stability of wheeled robot together. According to analysing the robot's structure, this paper studied the relationship between the traction and the stability, raised the influence of traction on the wheeled robot's stability, and set up traction-slip equation and traction-angle stability criterion equation, which not only enrich and improve the moving stability theory of wheeled robot,but also lay the theoretical foundation.This paper has 6 chapters, the major research contents and the results are as follows:ChapterⅠ: This paper introduced research background, significance and source of the subject, provided an overview of the current situation of the relationship between traction and stability of wheeled robot, listed the important research results at home and abroad, and showed the major research contents.ChapterⅡ: on the basis of the existing theory at home and abroad, this paper systematically studied the stability theory of wheeled robot, which include traction-slip theory and the traction-overturning theory, and creatively introduced zero torque (ZMP) theory into determining the wheeled robot's stability on the basis of which the traction-angle stability criterion was raised. This paper also analysed the various key points of wheeled robot by using the analysis method of space, derived the instable angle expression "two-degree of freedom wheeled robot with articulated body" under instable critical condition, and solved the specific questions on the basis of the structural parameters.ChapterⅢ: on the basis of the traction-slip theory, this paper established the wheeled robot kinematical equations combined with the multi-body dynamics method, derived the incidence formula of traction and slip rate, and defined the traction-slip equation. On the basis of combination of traction- overturning theory and zero-moment theory, this paper also summarized the traction-angle stability criterion which is considered as a new way of determining the wheeled robot's stability on the complex working condition, and to a certain degree which is used to fill space in the judgement theory of stability influenced by traction.ChapterⅣ: this paper considered the wheeled robot as a multi-body system by using the multi-body system dynamics, ignored the secondary factor in the system, and according to the unique structure of wheeled robot, this paper also set up the eight-degrees-of-freedom mathematical model of wheeled robot under the complex terrain condition by using the Lagrangian, which is a solid foundation of following simulation.ChapterⅤ: by setting up the system model in the ADAMS software, this paper did the simulation of stability of the wheeled robot, and then compared the simulation analysis result with the theory analysis one, thereby drew the corresponding conclusions.ChapterⅥ: this paper summarized the full text, and gave the advices about future research ideas.