Design And Control Of A Unicycle Self-balancing Robot

Recently,unicycle self-balancing robots have attracted much attention from domestic and foreign researchers.Unicycle self-balancing robots are a class of nonlinear,multi-coupling,nonholonomic,and underactuated systems whose modeling and controller design are an important problem in the field of robotics and automatic control.In this thesis,a unicycle self-balancing robot is built,and the corresponding dynamic model is established.Moreover,this thesis is also concerned with the problem of posture control for the unicycle robot.The main research contents are summarized as follows:(1)Realization for the unicycle self-balancing robotFirst,a unicycle self-balancing robot with inertia flywheel is designed and developed.The main work includes mechanical structure design,hardware circuit design and system software design.Specifically,mechanical structure design should ensure that the quality of the unicycle self-balancing robot is distributed evenly so as to meet the basic condition of self-balancing control.The hardware circuit design consists of circuit design and PCB design.The hardware circuit includes a microcontroller,a power module,a motor driver module,an angle sensor,a bluetooth serial communication,and so on.The system software design refers to the design of the control program for microcontrollers and the design of the control program for monitor computers.(2)Modeling for the unicycle self-balancing robotSecond,the self-balancing control principle of the unicycle self-balancing robot is illustrated.A rotating wheel enables the unicycle self-balancing robot to move forward and backward to obtain pitch(longitudinal)balance.A rotating disk is used to obtain roll(lateral)balance.Therefore,the unicycle self-balancing robot can be viewed as a mobile inverted pendulum for the pitch axis and a reaction-wheel pendulum for the roll axis.Moreover,the dynamics models for the unicycle self-balancing robot at roll and pitch axes are derived using the Lagrange equation.(3)Finite-time posture controller design for the unicycle self-balancing robotThird,a continuous finite time control strategy is proposed for the posture control of the unicycle self-balancing robot.For the balance control of the unicycle self-balancing robot,researchers usually adopt sliding mode control methods.However,sliding mode controllers have switching functions such that control signals are not continuous,which may result in a "chattering" problem.Therefore,according to the aforementioned dynamics models,two finite-time controllers are designed,which include a finite-time roll controller and a finite-time pitch controller.Furthermore,the stability on the unicycle self-balancing robot with the proposed finite-time posture control strategy is also analyzed.Finally,simulation results show that the proposed continuous finite time controllers can effectively deal with the "chattering" problem compared with sliding mode controllers.