Design And Motion Planning Of Metamorphic Folding Mechanisms And Wheel-legged Robot

In this dissertation,two types of metamorphic folding mechanism 2-URU mechanism and 8R-Folding mechanism were designed based on the design method of reconfigurable mechanism of motion branch transformation.The mechanism analysis and motion branch research were carried out respectively,and the motion evolution mechanism of metamorphic folding mechanism was revealed.Applying the metamorphic 8R-Folding mechanism to the trunk design of the wheel-legged robot,a new type of metamorphic folding wheel-legged robot is designed.It can fold twice,and the waist can rotate left and right and pitch up and down in the folding process,which proposing a new scheme for Multi-purpose.The main research content of this dissertation is as follows:Through the model simplification and equivalence of the lantern which with folding function,combining 4U linkage with the classic Sarrus mechanism to obtain the 2-URU mechanism.The mechanism was analyzed by using screw theory and higher order kinematic analyses,all the motion branches of the mechanism were solved,and the switch of motion branches between singular configurations were found,which revealed the reconfigurable kinematic mechanism theory of the metamorphic folding mechanism.8R-Folding mechanism is designed by combining the research of 2-URU mechanism and Queer-square mechanism.Compared with 2-URU mechanism,both of them have folding feature,while 8R-folding mechanism can fold twice.Through screw theory and higher-order kinematic analysis,we found three singular configurations and seven motion branches of the mechanism,and found the switching process of the moving branches of the three configurations.We fully exploited the characteristics of the mechanism and applied them to the body of the wheel-legged robot,so as to design a new type of metamorphic folding wheel-legged robot.The robot has three configurations and six motion modes,which can realize self-amplification and contraction.It integrates multiple motion modes into one to realize the change of robot form and function.Based on Geometrical Foundations and Screw Algebra for Mechanisms and Robotics to research the metamorphic robot mode switch,determining the switch drive location distribution,motion control and coordination between the trunk and wheel leg switch.Under the help of simulation robot structure mode switching process wheel leg joint axis changes and ensure that the trunk state switch structure state rear leg part also can realize the normal work and the switch,reducing the possibility of interference when switching modes.The kinematics analysis of the robot is carried out.Compared the toe working space difference between 8R-folding metamorphic trunk and traditional rigid trunk,clarified that the introduction of metamorphic mechanism can help the wheel-legged robot to achieve a wider range of operations and improve the flexibility of work.The gait planning and stability margin under each configuration of the robot were analyzed,and the gait planning strategy under three configurations was given.Simulation experiments were carried out to analyze the motion characteristics of the robot,and the transformation rules of the centroid-position of the trunk,the leg and the torque of joints were obtained to verify the feasibility of the robot design.On this basis,the assembly and production of the prototype of the metamorphic folding wheel-legged robot was carried out,and the prototype was debugged to improve the adaptability of the robot to different working conditions of complex terrain.