Bionic Research In Foot Of Mechanical Leg Travelling On Sand Based On Biological Assemble Characteristics Of Ostrich Foot

As the fastest bipedal on land,african ostrich(Struthio camelus),permanently lives in the desert.Ostrich hind limb has excellent characteristics to travel on sand.Especially ostrich's foot structure plays a crucial role during the high-efficient movement on the sand.In this paper,a kind of bionic mechanical that was leg suitable for walking on sand ground was designed using bionic engineering technology,which imitated the structural characteristics of ostrich hind limb and the rigid-flexible coupling mechanism of tendon-bone synergetic locomotion.The gross sample ostrich foot were dissected and biological assemble characteristics of ostrich foot were deeply analyzed.It was studied that the morphology structure of foot bone,the characteristics of phalanx and connection mechanism of bone-tendon.Combined with the literature data,the different tendons of ostrich foot were classified,merged and optimized.These tendons were used to reconstruct ostrich foot model and bionic design.This paper presented an optimization and splicing method for complex objects using the handheld 3D laser scanner.The ostrich foot model was scanned,spliced and reconstructed.According to the ostrich foot reconstruction model and combining with the morphological structure and relative position of ostrich foot tendon-bone,the three-dimensional solid model of ostrich foot were established,which provided basis for the foot structure design of bionic mechanical leg.According to the structure characteristics of biological assemble of ostrich foot,the function of ostrich foot tendon was imitated by bionic design.The foot structure of bionic mechanical leg was designed with tendon-bone biological assemble and rigid-flexible coupling.And the key components of bionic mechanical legs were also optimized.This paper analyzed the characteristics and working principle of foot structure of the bionic mechanical leg,and explored the function to travel on sand and cushion ability of bionic mechanical leg.The flexible model of wire rope was established based on the ADAMS/Cable module.The kinematics simulation parameters of the tendon-driven foot were set up for bionic mechanical leg.The correctness of the flexible model of wire rope was verified by simulation results,and the variation of foot structure was analyzed.The action travelling on sand of foot structure of bionic mechanical leg was verified based on the ADAMS simulation analysis,which provided a reference for the processing and manufacturing of bionic mechanical leg.The optimal design and manufacture of bionic mechanical leg was completed based on the analysis of simulation results.A linear servo electric cylinder that meets the requirements was selected.The control system of linear servo electric cylinder was built to test the parameters of speed and displacement.The optimization of the T-plate and the assembly and commissioning of bionic mechanical leg were completed.The bionic mechanical leg was installed on bionic mechanical leg test platform by T plate.The related performance of bionic mechanical leg was tested.The three-dimensional motion data that bionic mechanical leg moved at low,medium and high speed on hard and sandy ground were collected and recorded by the motion capture analysis system Simi Motion.According to the processing and analysis of data,it showed that when bionic mechanical leg moved at medium and low speed,the walking speed on sand ground is higher than that on hard ground.Interestingly,the situation is just opposite when bionic mechanical leg moved at high speed.The bionic mechanical leg has better adaptability on sand ground by analyzing the angle of ankle joint and metatarsophalangeal joint,the vertical displacement of knee joint,ankle joint and metatarsophalangeal joint,and the vertical displacement and velocity of phalanges of bionic mechanical foot.According to the analysis of foot plantar pressure,when bionic mechanical leg moved on hard ground,the second toe of main toe do not touch the ground,foot plantar pressure of toenail and auxiliary toe are about twice as high as that moved on sand ground.When bionic mechanical leg moved on sand ground,the sinking depth of foot becomes shallow with speed increasing.According to the test results,bionic mechanical leg can achieve the functions on sand ground that each phalanx touching ground at the same time,leaving ground in sequence and the toenail pushing off ground.The auxiliary toe plays the supporting role.Compared with hard ground,bionic mechanical leg has better adaptability on sand ground.This study provides a new research idea for solving the existing problem that legged robots and deep space explorer walk normally on sand ground.