Research On Obstacle-crossing Ability And Stability Of Parallel Torso Bionic Mobile Robot “torso-bio”

As a typical representative of intelligent robots,mobile robots have been widely used in planetary surface,rough ground,underground space and other complex dangerous environments to perform inspection,transportation,operation and other tasks.At present,mobile robots have become a research hotspot of many high-tech companies and colleges and universities all over the world.Among them,wheeled robot has the highest flexibility and maneuverability;however,the ordinary wheeled robot is limited by the constraints of chassis and wheel diameter,and its ability to pass through unstructured terrain is poor.This paper tries to solve this problem from the perspective of bionics.Bionic robot is an advanced stage of robot development.The design inspiration of mobile robot can be obtained from the mobile characteristics of various organisms in nature,so that the designed mobile robot can simulate a series of excellent performances of cheetah and other organisms,such as selfadaptability,robustness,movement diversity and flexibility.The main research contents of this paper are as follows.First of all,a 2-SPR/UPR(v A)/SPS parallel mechanism with reconfigurable hinges is designed and applied to the torso of a four-wheel-foot mobile robot.Using the characteristics of reconfigurable parallel mechanism with variable configuration and variable degrees of freedom,the torso deformation of the bionic robot is realized through different driving modes,so that the four-wheel-foot mobile robot can adjust the relative movement of the front wheels and the rear wheels to generate a bionic orientation,which improves the flexibility and adaptability of the bionic mobile robot to different terrain environments.According to the bionic characteristics of its torso,this mobile robot is named “Torso-Bio”.Secondly,the screw matrix of 2-SPR/UPR(v A)/SPS parallel mechanism is established,the degrees of freedom of the mechanism in R-phase and U-phase are solved and are verified by applying G-K formula.Two sets of inverse kinematics solutions of the mechanism are obtained using closed-loop vector method.The positive solution model of the mechanism in R-phase is established using particle swarm optimization algorithm,and verified by the inverse solution.The velocity Jacobian matrix of the driving joints and the moving platform is established using finite and instantaneous screw theory.Finally,the reachable workspace in R-phase and the translational workspace in U-phase of the mechanism are obtained by jointly using Solid Works and MATLAB software,which provides theoretical support for the optimization and practical application of the mechanism.Then,a center of gravity adjustment device is designed to compensate the center of gravity of the mobile robot “Torso-Bio”,and the mathematical model of the center of gravity analysis of the robot in the process of foot movement is established.A method for calculating the stability margin of the robot based on the center of gravity analysis model is presented.Based on this method,the atlas of the stability margin varying with the center of gravity is calculated,and then an optimization scheme for the center of gravity adjustment drive based on beetle antennae search algorithm is proposed.Furthermore,the driving scheme for vertical obstacles and trench obstacles are formulated,and the kinematics and dynamics are analyzed in Solid Works and ADAMS software.The robot“Torso-Bio” can successfully cross the vertical obstacle of 2 times the wheel diameter and the trench obstacle of 0.5 times the body length,and the motor torque and centroid variation are all within a reasonable range.The static is analyzed in ANSYS software,and the positions of the mechanism with the maximum force and maximum deformation are found,which provides a basis for the material selection and reinforcement treatment of the robot components.Finally,an intelligent control system in the V-REP environment is constructed and is verified.By installing a distance sensor,the robot “Torso-Bio” can automatically adjust its orientation according to the terrain changes in the process of movement to improve the passing ability.By installing sim350 laser detection radar,the robot can detect and model the surrounding terrain in real time during the movement process,and smoothly pass through continuous complex terrains by relying on the self-adaptive deformation of its bionic torso.The parallel torso bionic mobile robot “Torso-Bio”,which integrates the bionic concept,has greatly improved the obstacle-crossing ability of wheeled robots on the basis of retaining the fast and stable advantages of wheeled robots due to the reconfigurability of its torso.It can be widely used in narrow,dangerous and complex terrain that needs to pass through flexibly and quickly.