Research On System Design And Motion Control Method Of An Electrically Driven Wheeled-bipedal Robot

With the continuous expansion of mobile robot application scenarios,traditional legged and wheeled robots cannot meet the task requirements of adapting to complex environments and moving efficiently.The wheeled-bipedal robot combines the advantages of the legged robot’s good adaptability to complex environments and the flexible movement of the wheeled robot,which is the new generation of mobile robots with great potential for development.Once the concept of wheeled-bipedal robot was launched,it developed very rapidly.A variety of such robot platforms have emerged at home and abroad,and various control algorithms of wheeled-bipedal robots have emerged one after another.The wheeled-bipedal robot is a typical underactuated system,and the dynamic and stable motion control algorithm with strong robustness is the guarantee for its flexible motion.In view of the research hotspot and according to the stable motion requirements of wheeled-bipedal robot,this paper conducts research on the design of motion control system,platform construction,robot modeling,motion planning and control algorithms.The main research contents and innovations are as follows:1.System design and prototype platform integration of the wheeled-bipedal robot.According to the flexible motion requirements of the wheeled-bipedal robot,the structural configuration,the number of degrees of freedom,the overall size and the arrangement of the joint actuators are designed.According to the control requirements of the robot,a high stability and real-time motion control system is designed.The hardware design of the motion controller,attitude information sensor and in-wheel motor driver are carried out respectively.And,the signal interaction between each actuator and the motion controller is established.Finally,the wheeled-bipedal robot physical prototype platform is integrated.2.The kinematics and dynamics model of wheeled-bipedal robot are established.The kinematics model analyzes the forward and inverse kinematics of the robot,which calculates the position coordinates of the center of mass and establishes the mapping between the trunk pose and the angles of each joint.Moreover,a single-wheel leg dynamics modeling method is proposed to describe the relationship between links’ interaction force,the torque and the joint driving torque and realizes the complete mapping of the output force of the hip joint and the joint torque,which lays the foundation for the next robot motion control.3.A motion control method based on the inverted pendulum model is designed.Firstly,on the premise that the coordinate information of center of mass of wheeled-bipedal robot is known,the wheeled-bipedal robot can be simplified as a wheeled inverted pendulum model by considering the upper part on the wheels as a whole.Secondly,based on the inverted pendulum model,the balance and speed controller,turn controller and motion control algorithm are designed.Finally,in the simulation prototype and on the prototype platform,the speed following experiment,the turn following experiment and the changing torso height experiment have been completed,which realize the omnidirectional motion of the robot.4.A motion control algorithm based on whole body planning is proposed.Based on the simplified dynamic model of the robot,we establish a Whole-body Jacobian matrix with the torso posture as the task space and propose the motion control algorithm based on whole body planning which make unified planning and control for the hip joint,knee joint and ankle joint.In the simulation environment,the continuous unilateral bridge experiment,the centrifugal force compensation turning experiment and the slope turning simulation experiment are carried out.Furthermore,the terrain adaptation experiment is designed for the prototype platform,which effectively improve the overall stability and terrain adaptability of the robot and verifies the validity of the motion control algorithm.