| High-voltage power transmission tower is mainly distributed in the wild,where the terrain is complex and the environment is harsh.In order to ensure the safety of high-voltage power transmission tower,frequent inspections and maintenance are required.Traditionally,manual inspection is the most widely used method,with the disadvantage of being unsafe and inefficient.Therefore,the development of intelligent robots can climb along and inspect the transmission tower can not only improve the inspection efficiency,but also assist the high-voltage line inspection robot to complete the online and offline operations,which is suitable for the construction of smart power grids.In order to overcome the shortcomings of series and parallel robots,this thesis proposed a novel bipedal hybrid climbing robot,which is composed of two parallel legs and a body linkage connected the two legs.The finite element method is used to optimize the structure of the robot.Also,the dynamics model and climbing gait of the hybrid robot are studied based on virtual work principle and bionics.According to the characteristics of climbing gait,the PD controller with gravity compensation is used to reduce the joint error during movement.The feasibility of the robot is verified through simulation analysis and physical prototype experiments.The main research route and results of the thesis are as follows:(1)A novel lightweight bipedal hybrid climbing robot is designed.The robot is composed of two 3-degree of freedom parallel legs and a body linkage.Based on the typical transmission tower structure,we designed the configuration of the robot’s legs which would be able to climb along and cross obstacles on transmission tower.The body linkage and the adsorption were optimized by finite element,force balance and moment balance analysis to ensure that the robot can stably adsorb the transmission tower when carrying loads.Based on the mechanical configuration,climbing environment and bionics,the inchworm gait suitable for transmission tower climbing was proposed.Also,the motion form and switching conditions of each phase of the gait were analyzed.(2)Kinematics model and gait trajectory planning.We established the kinematics model of the robot through geometric method.The workspace of the robot was calculated,and the singular configuration in the workspace is studied based on the kinematics model.The trajectory was planned by Bezier curve and trapezoidal acceleration to improve the obstacle crossing ability and climbing efficiency.(3)According to the motion characteristics of the inchworm gait in different phases,the dynamic models of the single leg and both legs of the robot are established by the virtual work principle and the Newton-Euler equation which applied to the motion control of the flight phase and stance phase.In order to reduce the tracking error of the trajectory,the PD controller based on gravity compensation is used,and the stability of the control system is analyzed.(4)We established the virtual simulation experiment platform to verify the robot’s gait and trajectory tracking accuracy by MATLAB and Adams.The physical prototype of the hybrid robot was built based on the result of the simulation.The climbing performance of the robot was verified on the simulated environment and the actual transmission tower.The joint tracking error and torque during climbing were measured to verify the rationality of the design and gait of the robot. |
