Research On Motion Planning Method For Quadruped Robots Walking On Unknown Rough Terrain

As one of the main forms of legged robots,the quadruped robot can adapt to the unstructured environment by its legged locomotion and has a significant advantage in rough terrain adaptability.Due to the diversity and complexity of terrain environment,it has been a difficult problem to realize the adaptive and stable walking on the quadruped robot over the rough terrain.Especially when the quadruped robot faces to completely unknown rough terrain and is unable to perceive the terrain environment,it is of great value to research the motion planning methods for the quadruped robot.In order to improve the terrain adaptability and motion stability,the research on the adaptive and stable walking over unknown rough ternain for the quadruped robot is carried out on the quadruped bionic robot platform 'Chitu'.The main research contents and achievements include the following three parts:1.Modeling of the quadruped robot.The kinematics model of the quadruped bionic robot is built by using the link-joint model.The kinematics equations are deduced based on the D-H method,and then the inverse kinematics equations are solved by a closed form solution.2.Motion planning of walk gait.For the rough terrain,walk gait is used for the motion planning of the quadruped robot.According to the characteristics of walk gait,the state machine is introduced to control the gait and the online motion planning procedure is established.A path planning method and a center of gravity trajectory planning method are proposed respectively based on the stability criterion Center of Gravity(COG)and Zero Moment Point(ZMP),which can guarantee that the body trajectory of the robot is smooth and the quadruped locomotion is stable.3.Adaptation to unknown rough terrain.For the unknown terrain,a foot trajectory planning method is proposed to ensure the quadruped robot can realize the swing leg stride effectively over unknown rough terrain.Meanwhile,according to the terrain information obtained by the perception strategy,an adaptive control method for the centroid height and the posture of the trunk is explored while the quadruped robot is walking on unknown rough terrain.Finally,the experiments are conducted on the quadruped bionic robot,which prove the validity and reliability of the proposed methods.