Motion Planning And Control Of Lunar Wheel-Legged Hexapod Robot

In view of the rugged lunar terrain,wheel-legged mobile system shares the advantages of wheeled mobile system and legged mobile system,and realizes the complementary advantages.It has become one of the key pre-research projects of lunar exploration in China.The lunar wheel-legged hexapod robot was taken as the research object in this paper.We designed the mechanical structure of the robot and developed its control system,carried out the research of gait design,autonomous obstacle avoidance and attitude control,so as to build the principle prototype and carry on the test verification of the motion control algorithm.Firstly,the motion control system of the lunar wheel-legged hexapod robot was conducted the overall design.The task and performance requirements were expounded in this paper,to clarify the motion function and optimization direction of the robot system.We designed the robot's mechanical structure and the structure of motion control system,respectively,so as to complete the hardware selection of the motion control system and the establishment of the principle prototype.Secondly,the forward and inverse kinematics of the robot was analyzed.The modified D-H parameter method was used to model the robot's single leg,and the forward kinematics equation was established to obtain the working space.The Newton Raphson iteration method and the inverse kinematics analysis method based on the axis invariant were used to solve the inverse kinematics problem respectively.The trajectory of robot foot was planned in Cartesian space,and the human-computer interaction interface of MATLAB GUI was designed to carry out data simulation.Thirdly,the motion behavior design was carried out.In ADAMS virtual prototype analysis software,we conducted the design of “3+3” gait,in-situ turning gait and step-crossing gait.Based on the principle of behavior control,we designed the two behaviors of “obstacle avoidance” and “trend” with the adding of “expert experience”,to realize robot autonomous obstacle avoidance;and robot inverse kinematics algorithm was used,to conduct the attitude control of the hexapod robot under the condition of slope surface.The joint space corresponding to the robot at different inclination angles is calculated,and the attitude adjustment behavior is designed so that the robot can maintain the body attitude level on the inclined slope.Finally,the motion algorithm test was carried out to be verified.The human-computer interaction interface was designed,the robot motion control software was written,and the experimental verification of “3+3” gait,in-situ turning gait,touchdown feedback and slope attitude control was carried out for the prototype principle.The test results showed that the lunar wheel-legged hexapod robot can complete the corresponding motion function by motion control algorithm.