Gait Plan In The Uneven Terrain Of The Hexapod Robot Based On Multi-dimensional Space Coupled

The hexapod robot has a redundant structure and a discrete landing point and can achieve a variety of gait patterns,which makes it has a strong ability to adapt to the terrain.Therefore,the hexapod robot is suitable for outdoor uneven terrain operations.Under the condition of uneven terrain,a gait cycle of hexapod robot consists of three processes including the fuselage motion planning,the footend drop point planning and the swing leg motion planning.These three aspects are of great significance for the realization of the stable,efficient and accurate gait of the hexapod robot in the uneven terrain.The motion planning of the hexapod robot in the process of the uneven terrain was discussed in this paper including the fuselage motion planning,the footend drop point planning and the swing leg motion planning.The main research work and results are as follows:Firstly,according to the D-H algorithm and the vector diagram method,the kinematics of the robot was modeled,including the forward kinematics,inverse kinematics and differential kinematics.Then,the workspace of the footend of the robot was simulated by Matlab.On the basis of the above problems,a local environment modeling algorithm was proposed in this paper based on multi curve fitting to solve the problem of low fitting degree of existing local environment modeling algorithms.The algorithm had the advantages of low time complexity and high accuracy.Then,based on the robot kinematics model and the local environment model,the footedn workspace of the robot was solved.Secondly,aiming at the problem that the numerical method was more complicated to solve the problem of the workspace of the fuselage,a new algorithm based on multi-dimensional space coupled was proposed.The workspace of the fuselage was obtained by coupling the subspace of the fuselage,which was not involved in the inverse kinematics of the leg.On this basis,through the analysis of the fuselage deadlock reasons,the solution of the fuselage deadlock was proposed.Then,an algorithm based on the relativity of motion to adjust the position and pose of the fuselage was presented.Based on this,the initial motion parameters of the fuselage were optimized to complete the motion planning of the hexapod robot in the uneven terrain.Thirdly,according to the existing algorithm,a new algorithm based on multiple constraints was proposed.The geometry constraints and motion constraints were coupled in this algorithm.On this basis,Motion planning of the swinging leg,including swing leg foot trajectory planning,swing leg maximum stride planning and swing leg number selection planning was introduced.Then,the initial workspace of the body in the attitude angle of 0 degrees,10 degrees and 15 degrees was simulated through the Matlab.The simulation results show that the workspace of the fuselage decreases with the increase of attitude angle.Through the joint simulation of Matlab and Adams,the accuracy of the motion planning algorithm was verified by comparing the two kinds of motion planning algorithms,such as the reachability of the foot drop,the minimum stability margin and the change of the attitude angle.The correctness of the local environment modeling algorithm was verified by comparing the environmental 3D model and Matlab.The correctness of the footholds evaluation algorithm was verified through the comparison of swinging leg stride of two kinds of foot point evaluation algorithm.By comparing the velocity and acceleration curves of the foot with different trajectories,the correctness of the motion planning of the swing leg was verified.Finally,the hexapod robot experimental platform is constructed and the gait on the uneven terrain of the robot was simulated.The experimental results show that the proposed gait planning strategy can achieve stable,efficient and accurate gait.which makes it of practical value to popularize and apply the hexapod robot in outdoor environment.