Configuration Design And Passibility Study Of A Multimodal Mobile Robot Based On A Transformable Wheel Rim

The use of robots to perform dangerous tasks such as disaster search and rescue,explosive ordnance disposal,can effectively reduce casualties and improve operational efficiency.The complex,versatile and unpredictable terrain of such missions imposes stringent requirements on the passibility of the robots.However,the terrain passability and structural complexity of existing mobile robots often constrain each other: the robots with simple and compcact structure usually can achieve fast and efficient locomotion but poor terrain adaptability,while the robots with excellent terrain passability robots are mostly redundant and complex in structure.Based on above background,this thesis proposes a multimodal mobile robot with a transformable wheel rim and studies its configuration and passability,aiming to provide a new design theory and implementation method for multimodal mobile robot research.The main work and innovations of the thesis are as follows:(1)Based on an integrated design idea,an innovative design scheme for a multimodal robot that combines the functions of wheels,tracks,and legs without redundancy through the transformation and reconfiguration of the rim is proposed.According to the Axiomatic Design Theory,the functional requirements of adopting a wheel,track and leg hybrid robot to achieve all-terrain passability are clearly defined.By using the Theory of the Solution of Inventive Problems,a conflict matrix between terrain passability and structural compactness of present combined compound solution is created.The method of transforming the shape of wheel rim to achieve the switch of locomotion mode is proposed,improving the passability while maintaining the compactness of the structure.(2)Proposed three principles of configuration based on rim deformation to achieve robot motion mode conversion,and completed the topological configuration innovation design of deformed parts.By analyzing the travel mechanism and conversion principle of the different modes of the robot,the construction principles of two invariants(that is,changes in the contact mode of the rubber belt,changes in the freedom of movement of the deformed parts,and the circumference of the track ring)are summarized.The topological configuration of the rim and the stretched track wheel set was analyzed and synthesized,and the wheel frame extension scheme was optimized.By comparing key indicators such as performance and structural simplification,the two ends of the wheel frame unidirectional extension were finally grounded.Configuration of the deformed part.(3)A parametric input-output model of the transformation-driven spokes is constructed,and an optimized driving scheme for rim transformation is obtained by inverse solution.A kinematic model is established to support the deformation of the rim driven by the spokes with the input of the rim transformation angle and the spoke initial angle,and the output of the spoke length and the opening angle as outputs.By analyzing the corresponding relationship between the inputs and outputs,the support spoke model is reversely solved,two methods of length telescopic spokes and angle rotation spokes are proposed,and five different types of transformation driving schemes are obtained.By comparing the transformation driving dynamic characteristics and bearing strain static characteristics of different schemes,the length telescopic spokes are finally determined as the optimal deformation driving scheme.(4)A unified pose model that describes multimodal locomotion of the robot is established,and the passability of different modes is compared in theory.By introducing the rim transformation angle as a mode selection parameter,a modeling method combining a complete constraint and a non-complete constraint is used to achieve a unified expression of the kinematic model of the robot in different motion modes.Using a unified model,the method of combining theoretical analysis and simulation verification was used to compare and study the supporting and passing performance of the two movement modes of wheel and track,and the geometrical passing performance of the three moving modes of wheel,track,and leg against different obstacles.(5)A prototype of the multimodal mobile robot based on transfromable rim is developed,and the correctness of the configuration design and passability analysis are verified through prototype tests.Based on the conclusion of the configuration design,a prototype of a multi-motion mode robot is developed.The performance of the prototype is tested through the motion mode conversion test,the passability tests of soil tank and geometric obstacle.The feasibility of the configuration design and the correctness of the theoretical analysis are verified.The multimodal mobile robot based on a transformable rim proposed in this thesis integrates the functions of wheels,tracks,and legs totether without structural redundancy,which can adopt the most suitable locomotion mode according to the variable terrains.Compared with the traditional wheels,tracks and legs hybrid multimodal robot,it has the advantages of simple and compact structure,flexible and changeable movement,fast and efficient travel,and so on.The research results of this paper provide a new design scheme and implementation method for the innovative research of multimodal robots.The robot can be used as a universal mobile platform,equipped with different task modules to perform a variety of anti-terrorism detonation,search and rescue reconnaissance tasks.