Design And Control Of Self-balancing Vehicle System Based On Finite-time Stability Theory

In recent years,with the continuous development of mobile robot technology and its broad application prospect,mobile robot has become an important part of the field of robot research.As a special wheeled mobile robot,the two-wheeled self-balancing vehicle has a structure of two wheels with common axes,independent drive,and the center of gravity is located in the upper part of the whole vehicle body.It achieves the purpose of balance by controlling the positive and negative movement of the two wheels.Therefore,the two-wheeled self-balancing vehicle has higher requirements for control methods and has become an experimental platform to test the control effect of various algorithms.Two-wheeled self-balancing vehicle is a highly unstable,underactuated and strongly coupled nonlinear system,and its dynamic equation is also a multi-variable nonlinear high-order equation with uncertain parameters.Due to the particularity of its structure,it is necessary to reach the equilibrium state in a short time when it is disturbed by the outside,otherwise the body will have the risk of tipping over.As a mobile robot with special structure,it not only needs to maintain a stable posture,but also needs to reach the target position in a short time.Therefore,in the control system,aiming at the requirement of short time,the stability time is put forward as an important performance index,which indicates the speed of the system converging to the required state.In contrast to asymptotic stability,finite-time stability can ensure that the system’s stability time is bounded.For the attitude balance and dynamic position control of two-wheeled selfbalancing vehicle,the stability time,namely the convergence rate,can be used as an index to evaluate the control performance of the system.Therefore,the control research of twowheeled self-balancing vehicle based on the finite-time stability theory is of great significance.Based on the finite-time stability theory,this paper conducts a more in-depth study on the attitude balance control and dynamic position control of the two-wheeled selfbalancing vehicle.The main research contents are summarized as follows:First,this paper studies the balance principle of the two-wheeled self-balancing vehicle,and uses the dynamic method to analyze the physical equation of the twowheeled self-balancing vehicle to get its mathematical model.Then,the values of two inertial sensors,the accelerometer and the gyroscope are combined,and more accurate angle and angular velocity signals are obtained by Kalman filter.Finally,based on the above mathematical model and data information,an optimal controller(LQR)is designed to realize the attitude balance control of the two-wheeled self-balancing vehicle,and its effectiveness is verified by simulation experiments.Second,there may be unknown disturbance in the motion process of the twowheeled self-balancing vehicle,and approximation is adopted in the above modeling process.In order to solve these two problems,Active Disturbance Rejection Control is adopted to expand the state variables of the two-wheeled self-balancing vehicle to estimate the two parts,and the controller compensates the system through compensation to achieve a stable state of the system.In order to accelerate the estimation of the extended state observer,this paper improves the extended state observer(ESO),which is the core of ADRC controller.Based on the finite time control theory,this paper proposes and designs the finite-time state observer(FTESO).Combining with the designed LQR,the balance control of a two-wheeled self-balancing vehicle is realized,and its effectiveness is verified through theoretical proof and related experiments.Thirdly,as a special mobile robot,the two-wheeled self-balancing vehicle can also be the carrier of formation control.Therefore,this paper studies the problem of visual formation control of two-wheeled self-balancing vehicles.The acquisition of position information and the design of controller are the two most important problems.In this paper,April Tag is detected by the camera module to obtain the relative position information of the two-wheeled self-balancing vehicle relative to the external environment or other mobile robots.In order to reach the target position and form the desired formation in a relatively fast time,this paper adopts the sliding mode control as the formation controller.A double power reaching law is designed based on the finitetime stability theory,so that the two-wheeled self-balancing vehicles can reach a stable state in the formation control in a finite time.The effectiveness and reliability of the visual formation control method proposed in this paper are proved theoretically and experimentally.Finally,the main work of this paper and some problems in the work are summarized,and the future work is prospected.