Design And Analysis Of Variable Step Quadruped Robot With Flexible Spine

Spine can increase the flexibility,stability and coordination.Currently,quadruped robots mainly use rigid torso,which is insufficient in terms of flexibility,stability and coordination.Currently,the body of quadruped robot is mainly developed with rigid structure,which is deficient in speed,stability and energy efficiency.And the flexible spine based on the principle of bionics is a new kind of structure in quadruped robot,which can improve the coordination and the stability of motion posture and play an important role in the improvement of the performance of the quadruped robots.The variable stride leg structure avoids complex gait switching and allows the robot to better adapt to different terrain conditions,thereby improving the adaptability of the quadruped robot to the unstructured environment.Therefore,breaking through the structural constraints of the quadruped robot will help to expand the application field of the quadruped robot and promote the development of the quadruped robot to practical use.Although many high-performance quadruped robots have emerged at home and abroad,there is still a gap with bionic organisms in terms of coordination,stability and adaptability to irregular terrain.Based on the full investigation of the lumbar structure and leg structure of quadruped robots,this paper combines the miniaturization,low energy consumption and high efficiency of the quadruped robot to improve the motion posture stability and irregular terrain of quadruped robots.In-depth theoretical analysis,virtual prototype simulation and prototype testing,combined with bionics theory,optimal design method and computer simulation,the key issues of the spine structure,leg structure,kinematics and dynamics of the robot are further studied,the main research contents are as follows:(1)Based on the principle of bionics,this paper analyzes the structural characteristics of biological organisms and rationally simplifies its structure without affecting its main functions.According to the design requirements of the leg structure and the waist structure,the leg structure with variable stride and the bionic flexible spine structure with omnidirectional deformation are proposed,and the overall structure of the quadruped robot is rationally laid out.(2)Based on the analysis of the characteristics of the foot end trajectory during the movement of the biological organism,the requirements for the foot end trajectory of the quadruped robot are obtained.And the trajectory of the foot end of the robot is planned.Muti-genetic algorithm and goal attainment method are combined to optimize the leg structure.to determine the length and position of the bars in the leg structure.Then according to the force of the spine in different states of the robot,the cross-sectional diameter of the intravertebral flexible body that meets the target condition is obtained.and the flexible spine is topologically optimized by Ansys Workbench to meet the lightweight design requirements.(3)On the basis of analyzing the common gait of the tetrapod,the trot gait is selected as the object of dynamic analysis,then simplifies the dynamic model under the trot gait of the quadruped robot,and then analyzes the parts of the robot.The kinetic energy,potential energy and generalized force,etc.,derive a series of known quantities.Then according to the Lagrange equation,a dynamic model of a quadruped robot with a rigid torso and a dynamic model of a quadruped robot with a flexible spine are established.(4)Based on virtual prototyping technology,simulation experiments were carried out using Adams software.The results show that the optimized foot trajectory can meet the requirements of continuous smoothing and no abrupt change of trajectory,velocity and acceleration during the movement of the robot,and achieve the goal of design;the variable stride leg structure enables the quadruped robot to adjust the stride according to different terrains,avoiding complicated gait switching,improving the adaptability to irregular terrain,and verifying the feasibility of leg structure design;the flexible spine structure can reduce the fluctuation and offset of the center of mass of the robot and the required driving torque during movement,thereby improving the stability of the robot's motion posture,the accuracy of the travel route and saving energy.A quadruped robot prototype experimental platform was built,and the foot-end trajectory tracking experiment,the motion experiment under different strides and the contrast experiment under different trunk conditions were carried out.The correctness of the foot-end trajectory and the feasibility of the variable stride leg mechanism and the flexibility of the flexible spine structure for the robot's motion posture stability and the accuracy of the walking path are verified.