Analysis And Verification Of A Robot Foot With 3-UPS/S Parallel Mechanism

Due to leg-foot system,legged robot has discrete drop foot point so that legged robot has strong terrain adaptability and climbing obstacle capability.In view of the complex environmental adaptability requirements of the legged robot,the legged robot should have the ability to walk in complex terrains,and the foot is the only contact part between the robot and the ground,so it is necessary to realize the flexible and stable operation with load.At present,the foot that is relatively simple and has some shortcomings causes its performance to fail to meet high requirements and limit the development of the legged robot.Therefore,it is important to design a foot that can adapt to a variety of irregular terrains,climb hillslope and drop foot easily.It is of great value for expanding application of large heavy-duty legged robots.Firstly,from the functional requirements,a robot foot with 3-UPS/S parallel mechanism that satisfies the load capacity,self-reset and stability is proposed.Based on load requirements and walking terrain complexity,the flat footplate and the spherical joint are selected as the main structure of foot.In order to ensure that the foot is reset to the initial posture when lifting the foot,the innovative combination design of the parallel mechanism and the springs is proposed.The self-reset structure is analyzed from mobility characteristics,geometrical constraints,limb interference and self-reset performance which is decided by spring and gravity.Considering drop foot stability with various typical terrains,based on the Bekker pressure-sinkage theory,foot-terrain interaction model is built and the soil deformation calculation can be established.The influence law of the foot parameters on the soil deformation is studied,and extreme dimensions are carried out that foot can be in stable state on typical terrains.And then the relevant foot dimensions are carried out.Considering working conditions of the robot,a design scheme that foot pattern modules can adapt to a variety of terrains is proposed.The main parts are rationally designed and arranged to form the overall foot structure.Then,in order to reliability and load capacity of foot,the finite element simulation software is used to simulate the working environment,and the static and dynamic analysis of the key parts are carried out to judge that the function of each part does not damage.The dynamic analysis of the overall structure determines that the deformation and force state of foot can be in the tolerance range.Finally,the whole process of the foot is processed and conducted experiments.It verifies that the design of the foot structure can complete the adaptability,self-reset and bearing requirements.It is true that the foot structure meets the functional requirements of the robot.The research results provide certain reference for the foot design of the large heavyduty legged robot.Improving the comprehensive performance of the foot can expand the working range and application locations of the legged robot,which is of great significance to the development of the legged robot field.