| Aiming at the requirements of the carrying capacity and obstacle avoidance performance of the inspection robot,this paper systematically studies the innovative design of the topological mechanism and the optimization method of the dimensional parameters of a six-degree-of-freedom hybrid mechanism,and carries out the corresponding kinematics analysis and workspace range analysis.At the same time,the experimental verification of the relevant research content is carried out.The full text has achieved the following research results:(1)Aiming at the design goal of leg mechanism of inspection robot,according to the topological structure design theory of parallel mechanism based on position orientation characteristics,a 5-DOF parallel mechanism 5-UPU is proposed.On the premise of clear design objectives,the topological structure of each limb of the leg mechanism is synthesized,and a variety of limb structures are listed.The appropriate limb is selected and the mechanism is constructed according to the assembly geometric conditions,and the preliminary model of the leg mechanism is established.After checking the degree of freedom,judging the negative motion joint and designing the driving joint,the preliminary structural design of the mechanism is completed.(2)Aiming at the singularity problem of mechanism design,an asymmetric mechanism design method is proposed.Through the cooperation of different dynamic / static platform types,the structural dimensional parameters and limb dimensional parameters are generated.The dimensional parameters of the mechanism are optimized by two continuous dimensional synthesis,and the optimal dimensional parameter group of the mechanism under this topological structure is obtained,and the corresponding mechanism parameter model is established.According to the motion / force transmission performance analysis of the mechanism,and compared with the Stewart mechanism under the same dimensional parameters,the feasibility of the method is verified.(3)According to the actual motion characteristics of the inspection robot,a six-degree-of-freedom hybrid mechanism 5-UPU+R is constructed.Based on the design of the original parallel mechanism,an independent revolute joint is set in the center of the moving platform to construct a hybrid mechanism 5-UPU+R suitable for the leg structure.A performance index,regional transmission index,for evaluating the motion / force transmission of the mechanism is defined.Combined with the good transmission-position workspace and the generalized transmission index,the dimensional synthesis of the mechanism under the constraint condition as the leg structure is carried out.The parameter model of the leg structure is established,and the forward / inverse position analysis is carried out.Compared with the Stewart mechanism,it is verified that the hybrid mechanism 5-UPU+R has good kinematic performance as the leg structure of the inspection robot.(4)Aiming at the obstacle-crossing performance of the leg mechanism,the workspace range of the mechanism is studied under the constraint of the limb structure.Based on the conditions of revolute joint,prismatic joint constraint and limb interference in the mechanism,the actual workspace range of the mechanism is calculated,and the comparative analysis is carried out to prove that the inspection robot has better obstacle avoidance ability.In this paper,the theoretical basis of parallel mechanism design is systematically analyzed,and the design method for asymmetric parallel mechanism is established.At the same time,a leg structure suitable for inspection robot is designed,and the configuration analysis and dimensional parameter optimization of 5-UPU + R hybrid mechanism are carried out.Under the premise of ensuring the carrying capacity of the robot,the motion flexibility and obstacle avoidance ability are improved,which provides theoretical support for the design of asymmetric parallel mechanism and provides reference for the design of leg structure of wheel-leg composite inspection robot. |
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