Reasearch And Implementation Of Motion Control For Two Wheeled Self-balancing Robot

Two wheeled self-balance robot(TWSBR) is a type of mechanism robot according to the balance principle of inverted pendulum. It not only has the self-balancing robot structure and bionic characteristics, but also the design of wheel structure has the advantages of wheeled robot and practical function, and then can get more bionic learning characteristics with the development of the intelligent control technology. TWSBR can be approximately interpreted as a two wheel mobile inverted pendulum. It fits the inverted pendulum system of nonlinear, unstable and under-actuated characteristics perfectly, the complex kinematic, dynamic properties and wide application in the two wheeled robot has become a hotspot in control field. The establishment of mathematical model and different forms of locomotion control method is the important content of research in the field of control theory and robotics. So the research on TWSBR not only has the special significance of the scientific research, but also has the widespread application prospect.The overall system structure of TWSBR is designed and improved in this paper, then the corresponding mathematical model and three-dimensional simulation model are established. Based on the analysis of the dynamic characteristics of TWSBR, the motion control method is discussed, and the main contributions were as follows:First: System dynamics modeling and joint simulation analysis based on mathematical model and three dimensional modelTWSBR was abstracted as a rigid body system composed of two wheels and the main body. Under reasonable assumptions, the mathematical model of TWSBR is established by the method of Lagrange equations with the accurate system parameters which is obtained by simulation of 3D model. Through the combination of ADAMS and MATLAB simulation experiments, the mathematical model of TWSBR is analyzed and verified. Finally, the stability and controllability of TWSBR system are analyzed.Second: Motion balance control method based on cubic function PID controllerIn this paper, the motion balance of two wheeled robot is decomposed into the attitude balance control and speed control. The design philosophy of Cubic function of PID controller is recommend the mathematical properties of cubic function in the balance controller and speed controller, according to the dynamics of TWSBR and the mathematical analysis of controlled objects response in different states. With the angle of inclination of body error and robot velocity error as the input of the controller to achieve effective control of TWSBR’s angle and speed. Through contrast experiment with other control methods show that: for equilibrium attitude control problem, the control method not only can effectively increase the robot swing angle range, and has a stronger anti-interference ability, but also has the characteristics of fast response and the elimination of the oscillation near the equilibrium point, which greatly reduces the energy consumption of the system. Aiming at the problem of speed control, the control method can effectively eliminate the vibration phenomenon caused by the acceleration and deceleration time of the robot, and changes the running speed more smoothly. At the same time, the smooth running of the robot on the slope is achieved, and has a large range of stability and robustness.Third: Yaw motion control method based on double closed loop speed differential controllerAccording to the mechanical structure of TWSBR, the yaw motion control method based on double closed loop speed differential controller is designed in this paper. In this method, the output of the system is changed from the left and right wheel torque to the speed of the left and right wheel. And then according to the pre calibration of the left and right wheel speed differential value the relationship between t and robot turning radius r, which achieves precise control of yaw movement of the robot. Results show that this control method effectively compensate for the mechanical error of the system caused by the left and right wheel speed range phenomenon, greatly improves the control accuracy of the yaw motion of robot, adapts to the complex road environment, and has better stability and robustness. Robot can achieve the desired control objectives in the UMBmark and along the special line experiment.Forth: The robot behavior control method based on visual imageBased on the visual function of Kinect, the operator’s gesture is collected. The DTW algorithm is used to match the pre calibration gesture in the current operator gesture with template in database, and TWSBR is controlled by hand gesture recognition. Results show that the method can effectively control the robot in the complex illumination environment according to the requirements of operation, and recognition results meet the control requirements. The robot can realize the control function of natural gesture for TWSBR, and has good robustness and practicability.