Discrete Terrain Based Gait Planning And Structure Design For Humanoid Robot

With the development of science and technology,robots have been widely used in many fields such as industrial production,aerospace,disaster relief,and housekeeping services.Conventional wheeled and tracked robots,due to their structural limitations,often require continuous support surfaces for their movements,which makes it difficult to cope with more complex unstructured terrain such as gullies and steep slopes.Compared with traditional robot configuration,legged robots only needs discrete support surface to move,so they have better terrain adaptability.However,discrete terrain has the characteristics of constantly changing height and spacing,which makes traditional gait planning methods are often difficult to apply.In this way,the gait planning and autonomous walking control method of the humanoid robot under discrete terrain are studied,and the leg structure of the robot is optimized for the needs of walking.The details are as follows:First,a gait planning method for discrete terrain is proposed.The humanoid robot is reduced to a seven-link model.The relationship between joint angle,joint torque and joint space trajectories are established,using the kinematics and dynamics of the humanoid robot seven-link model.Aiming at the characteristics of variable height and variable spacing of discrete terrain,a two-step gait planning method is proposed.According to different target step locations under the discrete terrain,polynomial planning about time is used to plan the trajectory of the robot hip joint and swinging leg ankle joint.Considering various constraints in the actual movement of the robot,an fitness function is constructed.The differential evolution algorithm is used to optimize the robot's trajectory parameters,and a gait library is established to ensure the real-time gait planning.Then,a method for autonomous walking control of discrete support surfaces is proposed.Using lidar to detect the terrain,the target step location is obtained.the target step location is substituted into the gait library and the kinematics model to obtain the joint angle.In this way,we can drive the robot to walk.The co-simulation environment was built.the modeling of humanoid robot was completed under Webots and the autonomous walking controller was written in Matlab.In this environment,the correctness of the method was verified.Finally,the motion data returned by Webots is analyzed to provide a basis for subsequent structural design.Next,the leg structure was optimized.In consideration of wide motion range and large torque output of knee joint while walking on discrete terrain,a knee joint transmission scheme combining patella-like mechanism and oscillating guided bar mechanism is proposed.The differential evolution algorithm is used to optimize the design parameters,so that the transmission mechanism can maximize the hydraulic cylinder output margin while meeting walking needs.At the same time,to deal with the problem of large joint impact when walking on discrete terrain,different working conditions are established by using solid Thinking Inspire software and the topology optimization design of the robot leg structure is carried out.Finally,the structure is lightened while ensuring the strength.Finally,the research work of this paper is summarized,and the future research work is prospected.