Mechanism Design And Performance Research On Reconfigurable Ground Mobile Robots With Multiple Locomotion Modes

With the development of mobile robot technology,unmanned system has become an important trend,which means that the mobile robots should have strong adaptability to complex mobile environments,in the case of autonomous movement.The configuration is more demanding than that of a manned vehicle.Conventional reconfiguration,hybrid and other new mobile mechanisms have also been continuously proposed and developed to improve the robot's ground mobility.In this paper,the link mechanism is integrated with the robots,and a series of"reconfigurable multi-mode ground mobile chains" are proposed,which consist of several kinematic chains and platforms/vertices.Through its topological structure changes,multiple movements,the integration and switching on the same set of moving mechanisms,the movement function and reset function in any posture can be realized.The evolutionary design process of multi-mode mobile chain is proposed and systematically studied.The crawler-like movement pattern of the closed-chain linkage mechanism is proposed,and the obstacle-surpassing capability of the mechanism is enhanced by utilizing the characteristics of flexible deformation along with the ground shape in the moving environment of the linkage mechanism.Based on this idea,and working on the three-branch parallel moving mechanism(3-RRR,3-RSR)and four-branch parallel moving mechanism(4-R(3R')R,4-R(5R')R)respectively,this paper explores the configuration design,pattern topology analysis and obstacle-climbing capability analysis method,and the path planning strategy of multi-mode mobile chain.The specific research content is as follows:1)Based on the mechanics creative design method and the principle of bar reuse,three basic evolution rules are developed,namely,the evolution of branch,the evolution of the branch number,and the evolution of the link form.The evolutionary design construction process for "multi-mode ground mobile chain" of generalization,evolutionary reasoning,specialization and concreteness is established.2)A multi-mode 3-RRR rolling mechanism with a single degree of freedom is proposed according to the evolution law of the link form.On this basis,the mechanism is designed using the principle of singular position and redundant motor configuration,and a multi-mode 3-RSR rolling mechanism is obtained to realize the change of degree of freedom in the mode switching process,and the folding function in a single degree of freedom and the rolling function in three degrees of freedom can be achieved.3)According to the rule of evolution of branch number,a multi-mode 4-RSR parallel moving mechanism is proposed.Equivalent plane analysis principle is used to realize the integration of two kinds of scroll modes:Watt chain type and 6R chain type.The mechanism's rolling and operating function integrated design is realized by using the parallel mechanism's motion characteristics.The concept and feasibility for the application of the industrial intelligence assisted robots is illustrated.Equipped with lights and toolboxes,it can be useful in the maintenance,assembly and testing in small space.4)According to the evolution rule of the branch,a multi-mode 4-R(3R')R parallel moving mechanism is proposed.The method of changing the degrees of freedom and topological structure through singularity position switching is used to realize the integrated design for multi-mode of track-like,open-chain foot and wheel-like,and the method of analyzing the topological structure under each mode by using adjacency matrix and conversion equation is proposed,which is the basis for subsequent analysis of kinematics,mobility,etc.And with a further use of the evolution rule of the internal degree of freedom of the chain group and the design concept of branch variation,a multi-mode 4-R(5R')R parallel moving mechanism is proposed.It can be reconstructed into different topological structures to realize three kinds of locomotion modes and seven gaits(tracked rolling gait,stair and slope climbing gait,gap crossing gate,trot walking gait,wheeled fast moving gait and steering direction gait).The multi-mode design proposed by this method greatly improves the ground environment adaptability of the mobile mechanism,and also provides the necessary design ideas and key technologies for a highly adaptable ground mobile platform.5)For the tracked rolling locomotion mode proposed in this paper,based on the use of mechanical deformation along with the varied terrain.The obstacle-surmounting gait planning and the establishment of a kinematic model for analysis in basic obstacles environment(stairs,slopes and gaps)are demonstrated.It is verified that it has stronger obstacle avoidance ability than the traditional movement method under the same size.Based on the chessboard-shaped grid division(CGD),the least time-consuming and shortest-distance path planning strategy for multi-mode ground mobile links is established.