Bionic Research In Energy-saving And Vibration-reducing Mechanical Leg Based On Hind Limb Of Ostrich

Legged robot could do some dangerous work due to the better passing ability and adaptability on the unconventional ground,such as planetary surface exploration,disaster prevention,detecting the enemy’s situation,rescue,etc.The leg plays a significantly crucial role in the robot motion.Therefore,it is worthwhile to design a mechanical leg with special functions and performances.However,it is difficult to improve the characteristics of the mechanical leg by the traditional method.Bionic is becoming more and more efficient in solving some industrial problems by breaking the traditional and getting inspiration from the nature.Therefore,the performance of the mechanical leg could be sufficiently improved in energy-saving and damping.African ostrich(Struthio camelus),permanently living in the desert,is capable of remarkable speed,exceptional endurance and continuous locomotion.Such high-speed running is attributed to muscles,tendons,legs,feet,other anatomical structures and their mutual coordinations Therefore,the ostrich hindlimb was chosen as the bionic prototype and applied to the design of legged robot.Firstly,the law of ostrich locomotion was analyzed by high-speed camera and three-dimensional motion tracking analysis system.Results showed that the phalanxes of the 3rd toe successively get away from the ground in the phase of lift-off.In addition,the ostrich toes would produce the gripping and pedaling force in the entire contact process.The passive rebound characteristics of ostrich intertarsal joint were studied through experimental method.The experimental results indicated that the maximum joint angle of the intertarsal joint was 168 degrees.Moreover,When the angle of the intertarsal joint was less than 105 degrees,the passive rebound characteristics of the intertarsal joint were not obvious.The biological mechanism of ostrich was studied through the general anatomic test and related literatures.The tendons and bones of the ostrich legs have Rigid-flexible coupling characteristics.During the process of ostrich foot touchdown,tendon-bone interaction mechanism can convert the ground reaction force into huge tendon tension and bone pressure.The energy,consumed in the ground impact,can beconverted into the elastic potential energy.As a result,the energy would be released in the phase of lift-off to improve the motion efficiency.In addition,when the ostrich runs at high speed,it was found that the interaction between tendon and muscle can effectively protect the muscle from injury by the power attenuation effect of the tendon.Based on the biological mechanism and locomotion rules of ostrich,three kinds of bionic mechanical legs were designed using similarity principle and Bionic Engineering Technology.Meanwhile,the dynamic simulations of the three kinds of mechanical legs were carried out by Adams software.Through comparison and analysis,the bionic mechanical leg III was better performance than the other two mechanical legs in energy saving,so the bionic leg III is the best choice for the design of the mechanical leg.The running speed of the bionic mechanical leg III was about5.843 m/s,and the effective value of vertical acceleration was about 10.5 m/s2.The energy consumption was about 1552.23 KJ in a sports cycle,and the Co T(the cost of transport)is about 8855.2.The motion simulation analysis of the leg component of a bipedal ostrich robot is carried out so as to further study the performance of the leg III.Through the analysis of the simulation results,we can see that the effective value of the vertical acceleration of the body centroid was about 10.0 m/s2,the energy consumption was about 114.83 KJ and the Co T was about 1610.9.The kinematics and mechanics test platform of the mechanical leg was developed.The motion performance of the mechanical leg was studied by the mechanical test combined with the motion analysis system(Simi Motion),vibration measurer and the thin film pressure sensor.The experimental results showed that the mechanical leg III has realized the functions of the the mechanism of tendon-bone interaction,the mechanism of tendon-muscle interaction,the permanently elevated metatarsophalangeal joint and successively get away from the ground.Moreover,the effective acceleration value of the fuselage was about 0.5 m/s2 in the vertical direction.When the mechanical leg ran at the maximum speed,the Co T was about 3.6.