Research On System Design And Locomotion Control Of A Bipedal Leg-wheeled Robot

As the application scenarios of mobile robots gradually expand from simplex and structured environments to complex and unstructured circumstances,the traditional bipedal or wheeled robots are difficult to handle complex tasks in such complex environments.Bipedal leg-wheeled robots are regarded as next promising generation of mobile robots due to their strong adaptability in human living and working environments,good pass ability to obstacles,fast moving speed and good flexibility on continuous flat surfaces.However,researches on bipedal leg-wheeled robots started in the late 1990 s and the system design and control theories of the robots are not mature enough,which makes bipedal leg-wheeled robots a long way to actual application.This dissertation introduces the mechatronics design,robot modeling and motion control of a bipedal leg-wheeled robot and development of the prototype.According to the functional requirements of the robot,the overall structure scheme of the bipedal leg-wheeled robot was proposed,and the kinematics model of the robot was derived based on the position constraint of the center of mass(COM).Starting from the motion requirements of the robot,the determinations of robot degree of freedom(DOF),structure configuration and overall size were analyzed.And the robot structure was determined with 6-DOFs,leg-wheel fusion figuration and proportional to human lower extremity size.Based on this robot structure,the forward and inverse kinematics model derivations for the robot was conducted with respect to constraint of robot COM,which provided available theory models for robot motion control and simulation.According to the overall structure scheme of the bipedal leg-wheeled robot,the mechanical and electronical system design of the robot was carried out.After analyzing the requirement of mechatronics system,the mechanical structure,power system and the hardware of the control system were developed in detail.And a lightweight and compact robot prototype was built.Based on the structural characteristics of the bipedal leg-wheeled robot,the control strategies for robot motion were designed,and the software of the robot system was implemented.The robot joints motion control adopts the build-in position servo mode of the joint actuators,and the wheeled motion control adopts proportional integral differential(PID)control method to design the robot balance,velocity and steering motion controller.According to the design results of robot electromechanical system and motion controllers,the software for the robot was developed.The robot can realize sensor data processing,hardware communication and motion control algorithm through the software.Simulations based on ROS-Gazebo and several experiments on the actual robot prototype were conducted to validate the feasibility of the robot mechatronics system,kinematics modeling and motion control strategies.