Research On Motion Control Method Of Hexapod Robot Based On Whole-body Control On Complex Terrain

With the further development of human science and technology application and the exploration of nature,higher and higher requirements have been put forward for the mobile ability of robots,which requires it to be able to move autonomously in complex terrain environment.Compared with wheeled or tracked robots,legged robots have the ability to overcome obstacles and adapt to complex terrain,which can be used as a multi-degree-of-freedom mobile platform to complete mobile tasks in unstructured terrain.For the movement control problem of hexapod robot in complex environment,the highly adaptive motion planning algorithm and control method framework of hexapod robot system are studied to achieve the coordinated control of base motion and foot motion and multi-task motion planning.In this paper,the research is carried out with the progressive relationship from the configuration of the robot structure to the gait and motion planning of the hexapod robot to the overall control of the hexapod robot.The main research contents are as follows:1.For the feasible body and leg bionic configuration of the robot,the kinematics analysis of the two leg bionic configurations is carried out,and through the simulation analysis under fast motion conditions,combined with the torque and power requirements,the body configuration and leg configuration is given.Then the gait planning and slope adaptation strategies of the hexapod robot are studied.Simulation experiments show that the slope adaptation strategy can effectively improve the robot's static stability margin under sloping terrain,thereby improving the robot's stability and walking ability under sloping terrain.2.In order to improve the robot's ability to adapt to the environment and the ability to move in a complex environment,a whole-body motion planning method based on the optimal allocation algorithm of torso position and footholds is adopted.Using quadratic planning,with trunk motion stability and joint working space limitation as inequality constraints,trunk position and footholds as decision variables,and based on task priority,the optimal allocation of trunk position and footholds is realized.The simulation experiment shows that by adjusting the priority weight of the task,the task with higher priority can be executed first when the motion tasks conflict,and the coordinated movement of the trunk and the end of the swinging foot can be realized.3.In order to solve the shortcomings of large foot impact force and unable to adapt to complex terrain caused by position control of the hexapod robot,an active compliance control method for a hexapod robot based on the optimal distribution of foot force is introduced.In the supporting phase,the optimal distribution method of foot force based on the virtual model of trunk is adopted,and the virtual force of trunk centroid is distributed to the supporting foot by quadratic programming to obtain the optimal foot force.By adding a virtual model between the swing foot and the desired foot end position,the three-dimensional virtual force of the foot end is obtained,and the smooth switching between the swing phase and the support phase is realized through the state machine.The effectiveness of the control method is verified by the simulation experiments in different terrain.The robot can maintain good mobility,stability and robustness even when it suffers from unexpected disturbance on uneven terrain and slope.