The Mechanism Analysis And Design Of Bionic Eight-legged Robot

With the continuous enlargement of robot's application field,eight-legged bionic robot as a more and more effective solution by assisting or replacing human work in unstructured terrain environment has getting more attention.In this paper,a kind of eight-legged bionic robot's leg mechanism and the whole machine mechanism were designed with spider as the bionic prototype,and its problem of kinematics,dynamics,stability,gait and trajectory planning were studied.The coordinate transformation method,geometric method and derivative method were used to analyze the position relationship between foot endpoint location and driver input,and the mathematical formulas of the forward and inverse position solution of single leg,joint velocity and force transfer were derived.Based on the workspace geometry,the connecting rod scale parameters of leg mechanism was optimized and choosed.The kinematic property of single leg was analyzed based on two indicators of dexterity and mechanical transmission performance.The kinematics of the whole machine and dynamic redundancy were analyzed,Using Lagrange method,the dynamic equation of the single leg,the dynamic equation of the whole machine and the dynamic constraint equation with the reaction force of foot as the generalized input were established.The installation angle and maximum step length of the mechanical leg were determined based on move mode.Analysed the stability of the robot under different moving modes and grouping modes,then the Z-shaped grouping with spider moving mode was determined as the four-legged gait of the robot,sixteen kinds of high stability six-legged gait was planed,six types of mechanical leg layout and its grouping modes was given while the leg of the robot has damaged.The influence of the robot's centroid height and slope angle on the stability of the robot was analyzed under the four-legged gait straight walking mode.According to the walking speed requirement of the robot and the workspace solution result of the leg mechanism,the foot trajectory planning was carried out,then the mathematical model of foot motion trajectory was established,the simulation of virtual prototype verified the correctness of the model and trajectory planning.The research results of this paper lay a theoretical foundation for the development and application of this kind of eight-legged bionic robot.