Research On Omnidirectional Motion Planning Of The Hexapod Walking Robot In Natural Terrians

Hexapod walking robot is a special robot with redundant drivers,multi-chain, and time-varying topology. It presents a superior mobility in naturalterrains and an outstanding failure tolerance during static stable locomotion evenwith one or more of its legs damaged. Moreover, the torso, its supporting legsand the supporting ground can form a parallel robot platform with the swing legsserving as the manipulators, capable of carrying out complicated tasks with thecoordination of its legs.However, even the best hexapod walking robot still suffers from greatlimitations, caused by low speeds, difficulty in building and complex planningalgorithms. Currently, many specialists devote themselves to the research ofmotion planning tactics of hexapod walking robot, aiming at improving itsmotion stability by means of minimizing energy consumption, improving gaitmovement, balancing feet forces and joint torques and so on. By contrast, littleresearch has been carried out on omnidirectional motion planning tactics, toensure movement efficiency and stability. Also the existing research mainlyfocuses on structured terrain, while little on natural terrains. Therefore, with thefocus on researching the omnidirectional motion planning tactics of hexapodwalking robot on natural ground, this paper can fill the gap and is of greatimportance.This paper discusses the hexapod walking robot kinematics problem andparametric modeling. With the use of screw theory and exponential productformulas, first it analyzes one foot kinematics, statics, workspace, and the robotsystem kinematics and based on this, it researches robot static equilibrium theory,quantitatively analyzed the effect of step length coefficient, the yaw angle,shape-parameter, position-parameter and other factors on the hexapod walkingrobot’s static balance to propose a universal evaluation standards on stability anddesign a configuration adjustment method taking both efficiency and stability ofmotion into consideration. Out of the stability requirements and configurationadjustment, it creates a foot-holds selection method, torso motion planningmethod and foot trajectory planning method, for hexapod walking robot during omnidirectional locomotion in natural terrain by combining the natural terrainanalysis and path planning. And it uses the inverse kinematics of the robotsystem to understand its motion planning tactics and gets the trajectory of alljoints. Integrated with all the methods used in motion planning, it designs acommon omnidirectional motion planning and simulation algorithms for hexapodwalking robot in natural terrain.According to hexapod walking robot’s kinematic simulation and dynamicsimulation results, this paper verifies the path planning method by comparingrobots’ walking paths, verifies the torso motion planning method by comparingposture curves. According to the simulation results of different structuralparameters of robots’ motion in the same terrain and same path, it verifiese thefoot-holds selection method by comparing robots’ foot-hold-triangles, verifiesthe foot trajectories planning method by comparing the joint trajectories. Bycomparing all unit optimal motion stabilization margin curves, it verifies thestability evaluation standards criteria of the robot and their motion stability.Through prototype experiment, it verifies the omnidirectional motion planningand simulation algorithms of hexapod walking robot in natural terrain.The experimental results show that this algorithm has considered both themovement efficiency and stability and can be successfully applied to anyhexapod walking robot with practical value for further research and application.