| In order to increase the adaptability scene and application scope,wheel-legged robot is proposed.The wheel-legged co-driven robot can be simply controlled,but it is not reliable and can’t adapt to complex terrain.The wheel-legged independent driven robot is reliable and can adapt to complex terrain,but it can’t be simply controlled.In this thesis,by combining two kinds of single-loop closed-chain mechanism which is simply controlled and reliable,a single-loop closed-chain metamorphic mechanism with two kinds of motion forms is proposed.According to the arrangement principle of the closed-chain legged robot,a deformable wheel-legged co-driven robot is constructed.The theoretical analysis,simulations and prototype tests are carried out.Firstly,by combining Chebyshev linkage mechanism with parallel quadrilateral linkage mechanism,three kinds of single-loop closed-chain six-bar mechanisms are proposed.They are compared,and the single loop closed chain 2RP3 R mechanism is selected as the research object.The kinematics model of the mechanism is established by kinematics analysis.Based on the analysis of metamorphic principle,the structure transformation process of the mechanism is described by using the correlation matrix method,and the adjacency matrices under different isomorphisms were obtained.The modeling design is carried out to determine that it can be used as a mobile unit of wheel-legged robot.Then,using the construction method of dual-quadruped closed-chain legged robot,a deformable closed-chain wheel-legged robot which has four wheels and eight legs are constructed,and all the motion forms of the robot are determined.According to these motion forms,the design of the moving mode and the feasibility analysis of the moving mode are carried out.The wheeled mode and the legged mode are obtained.The switching strategy of the modes is formulated.The terrain adaptability of the robot is analyzed and the adaptability in different complex terrains is improved.The moving performance,statics,stability and trench-crossing process are analysis.Finally,a dynamics simulation model is established.The movement simulations of the robot are carried out,and the driving torque during ground-movement is measured.The simulations of switching process between different modes and gaits and the terrain adaptability are also carried out,and the position changes of the center of mass during switching process are measured.Based on the size data of the simulation model,the prototype is fabricated and the feasibility of the idea is verified by carrying out the ground moving tests and climbing tests in the two modes. |
