Research On Gait Generation And Leg Controlling Of A Hexapod Robot Over Unstructured Terrians

Hexapod robot has a strong ability to adapt to unstructured terrain due to theredundancy of its leg structure, characteristics of time-varying topology anddiscreteness of its footholds selection. Footholds selection, being an important partduring of the movement of hexapod robot, its reasonability is closely related to themoving stability, motion speed, and overstepping ability of the robot. Therefore,studying the gait generation of hexapod robot in unstructured terrains has greatimportant theoretical significance and practical value.In this paper, firstly the structure of the hexapod robot is described, andkinematics of swing leg and workspace of the foot-end are analyzed from theperspective of serial robot based on the theory of robotics, as well as the kinematicsof torso and torso workspace from the view of the parallel robot. Afterwards, thesimulation results of ADAMS and the computed results of MATLAB are comparedto verify the analysis of kinematics of series-parallel structure. To have themaximum flexibility in movement, the initial state of the hexapod robot isoptimized using Multi-Objective Partical Swarm Algorithm.Based on three-legged gait, the footstep of hexapod robot is planned combiningwith the known terrain information, i.e., gait generation. The small-scale fastplanning strategies is proposed to select the drop-foot point for rapidity andeffectiveness. A series of penalty functions can be generated by analyzing terrainconstraints, motion constraints of robot and stability constraints needed to beconsidered in the select of the drop-foot point. Comprehensively considering thepenalty function and using them to evaluate the foot drop point, the footholds planin this paper is transformed into an optimization problem which is solved by AntColony Algorithm. Finally, MATLAB simulation is carried out to verify theeffectiveness of the footholds plan.After fully considering the ability of robot motion and terrain constraints,hexapod robot whole-body movement is planned. In order to meet the flexibilityrequirements of the walking six-legged robot, impedance control strategy based onlocation tracking is adopted. Furthermore, the performance of the force tracking ofit is also analyzed, putting forward a more effective direct adaptive impedancecontrol. Finally, the co-simulation of MATLAB and ADAMS verifies the validity ofthe control strategy.A dynamic simulation platform based on ADAMS is established to confirm footstep plan and motion plan in unstructured terrain. To further verify the aboveplan, the physical experiment is designed and the experimental results are analyzed.Finally, a six-legged robot leg platform is built to verify the performance of forcetracking of direct adaptive impedance control.