Design Method For An Adaptive Bio-inspired Foot Mechanism Based On The Tetrahedral Mast Tensegrity Structure

The stable locomotion of adaptive complex terrain of the humans and other animals is achieved through their morphology and physiological structure in nature.As the only part in contact with the ground,the foot fully demonstrates unique structural characteristics.The locomotion of the humans and other animals by the foot with flexibility and adaptability characteristic is adapted,and the energy is absorbed and released on complex terrain,while promoting the stability and suppleness of the human body.In order to make the humanoid robot's foot have a locomotion function similar to that of the human foot,according to the theories and methods of the bionics and tensegrity structures,the paper that the adaptive bio-inspired foot mechanism is designed by integrating the morphological structure of the human foot with tensegrity structures,and adaptive locomotion is realized on sloped terrain.The main research contents of the paper mainly include the following aspects:(1)Human foot locomotion mechanism and morphological structure.Based on the theories and methods of the bionics,the locomotion mechanism and morphological structure of the ankle and foot are extracted.According to the coupling relationships of the factors of the foot and calf,a musculoskeletal coupling model of the foot is established.A simplified model of the biological mapping of the human foot is established by the morphological structure of the foot is simplified.(2)The research on the theory of tensegrity structures.Through the theoretical study of a tensegrity structure,the constructional method and structural characteristics of tensegrity structures are obtained.According to the constructional method of tensegrity structures,combined with the simplified model of the foot bio-mapping,a tetrahedral mast tensegrity structure analogous to the foot,the equivalent mapping model and deformation fearures are estanlished,respectively.(3)The mechanical structural design,motion analysis and simulation of the bio-inspired foot mechanism.The configuration design of the mechanism is obtained based on bionic principles.The size parameters of the mechanism are determined based on the physiological structure size relationship of the human foot,and the physical model of the mechanism is drawn by CATIA.Combined with the characteristics of the motion of the human body,the theoretical method of mechanism motion analysis is given.The kinematic solution is analyzed using the inverse dynamics method,and the spring stiffness is matched.According to the locomotion characteristics of the human foot,the locomotion characteristics of the mechanism are matched.In the ADAMS software,the bio-inspired foot mechanism simulation model is created by defining the density,constraints,and force drives of the model.The kinematics simulation of the model is carried out by setting reasonable simulation parameters,and the main simulation results of the mechanism are compared with the theoretical calculation data to verify the validity of the proposed method and the correctness of the theoretical calculation formula.(4)Fabrication and test of the physical prototype.According to the biometric characteristics of the synovial joints of the foot,the bio-inspired joints design is designed by the elastic rope to simulate the biological characteristics of the ligaments.The physical prototype is manufactured by 3D printing technology and debugged.The shape adjustment of the prototype is realized using passive deformation.And adaptive locomotion of the mechanism is achieved on complex terrain by the physical prototype test.Through the physical prototype test,it is observed that bio-inspired foot mechanism has a good adaptability and stability,the characteristics of the locomotion is mimiceked and the adaptability is improved compared with the conventional robotic foot mechanism.Taking the human foot as a bionic model,and the configurational design of the mechanism is achieved combining with the theory of tensegrity structures for solving the problem of adaptive locomotion of the foot and ankle of the humanoid robot.