Research And Realization Of Spherical Wheel Self-balancing Robot Based On Three Omni-wheel Drive

Motion control and attitude control are ubiquitous problems in Robotics.The selfbalancing robot is a special kind of robots that maintain their balance through their own movements.Different from ordinary wheeled robots,The spherical wheel selfbalancing robot(SWSR)is supported by a spherical ball and can move flexibly to any directions without changing the heading angle..It is a typical nonlinear,strong coupling and under-actuated system.The modeling,self-balancing and motion control are the key issues of the control science.The research contents of this paper are system design,dynamics modeling and balance control of SWSR.The contents include: physical system design of the robot,including the mechanical structure design of the robot,the design of the electrical and drive system,and the programming of the main controller based on the ARM;By calculating the kinetic energy and potential energy of the various parts of the robot,the three-dimensional dynamic model is established by using Lagrange equation.A double loop nonlinear PD controller is designed to achieve the two-dimensional plane motion and balancing of the robot.The co-simulation experiment environment and physics experiment were carried out to test the robustness of the robot.The key study and achievements of this paper are as follows:1)Spherical wheel self-balancing robot physical system.The mechanical structure of SWSR based on 3 omnidirectional wheel drive was designed by using Solidworks software,and the robot was completed.The electrical circuit system of the robot was built,including attitude detection system,control system,execution system,power supply system and communication system.Based on the time slice polling algorithm as the basic structure,a control program framework based on STM32 processor is set up,which allows the CPU to process different tasks in different time slices and improve the operating efficiency of the program.2)Based on the Lagrange equation,the dynamic model of the spherical wheel selfbalancing robot is established.Firstly,the robot is modeled,which can be decomposed into the fuselage,the spherical wheel and a driving wheel,then calculate the kinetic and potential of each part,a driving wheel is virtualized in each plane,the conversion relationship between virtual and actual torque moment is to decouple the robot.The establishment of the 3 dimensional mathematical model of the robot using the second type Lagrange equation.The zero input response and zero state response experiment of the robot are performed in the Matlab environment,verify the correctness and validity of the mathematical model.3)Double loop nonlinear PD control of spherical wheel self-balancing robot.Aiming at the pitch and roll direction of SWSR,a double closed-loop control structure based on non-linear PD is designed to control the robot's balance and motion.The nonlinear PD controller is designed for the yaw motion of the robot.The analysis of the experimental results shows that the controller has good effect on both balance control and displacement motion control.4)The joint simulation experiment and the physical experiment based on the spherical wheel self-balancing robot were carried out.In order to solve the problem that the mathematical model cannot really reflect the actual operation status of robots,the virtual prototype technology is applied to the robot simulation experiment.The robot virtual prototype model is established by using ADAMS.The controller of the robot is built by using MATLAB/Simulink.In the fixed-point self-balancing experiment,the robot can maintain its posture balance while keeping the robot in place.In the walking straight-line experiment,the robot can move in any direction in the two-dimensional plane while maintaining the posture balance.In the robust test experiment,the robot can resist certain external shock disturbance in the condition of maintaining the attitude balance.In physics experiments,the self-balancing experiment of the robot is carried out,and the feasibility and effectiveness of the designed control algorithm are verified.This research is supported by the Key Project of S&T Plan of Beijing Municipal Commission of Education under Grant No.KZ201610005010.The main purpose of this paper is to study the physical system structure,the establishment of the dynamic model and the motion control algorithm based on the posture balance for the spherical wheel self-balancing robot system.The achievement of this project is of certain significance to improve the design level of the spherical wheel self-balancing robot and to promote its application.