Research On The Stability Of Non-Coaxial Two-Wheeled Self-Balancing Mobile Robot

The non-coaxial two-wheel self-balancing mobile robot is based on the gyro torque produced by synchronous precession of a pair of gyroscope rotors to achieve static or dynamic equilibrium.In the course of transporting or carrying out the task of reconnaissance,it is very easy to be knocked down by external forces and can not continue to carry out the task,so it is of great significance to improve its running stability.The stability of the robot is evaluated by its rolling angle,which is related to the control system of the steering motion and the double gyro balancing device.When the robot moves or is hit,the rolling angle is directly controlled by the gyroscope's precession,while the precession angle makes the control system collapse if it is too large;However,the robot steering motion can produce centrifugal force,which causes the robot to flip outward and may be dumped.Therefore,aiming at the problem of poor stability of the robot,based on the principle of double gyroscope balance and the mechanical analysis of steering motion,the stability of the robot is studied from mathematical modeling,control algorithm design and optimization,control system design and so on.Firstly,the influence of double gyroscope control and steering control on the stability of robot is analyzed theoretically,and the relationship between the precession angle of the gyroscope,steering angle,running speed and rolling angle of robot gyroscope is obtained.Next,a four-degree-of-freedom dynamic model for robot steering angle,rolling angle,running speed and precession angle is established by using Euler-Lagrange equation and angular momentum conservation.On this basis,the sliding mode control algorithm based on precession zero compensation and the centrifugal force compensation is designed.The stability of the robot is simulated from three aspects of self-balance,anti-jamming and steering motion in Matlab.It is proved that the designed control algorithm can guarantee the stability of the robot.The fuzzy algorithm is designed to schedule the parameters of the sliding mode algorithm and optimize the sliding mode control algorithm.Then,the function requirements of the control system are analyzed.The hardware circuit and PCB board of the control system are designed;Peripheral motors,drivers and sensors of the control system are selected;And the module program of sensor acquisition,motor control,double gyro balance device control algorithm,motion control algorithm are compiled and debugged.Finally,the robot prototype is built to experiment the stability of the robot from the self-balance,anti-interference and steering motion.The experimental results show that the optimized fuzzy sliding mode control algorithm can make the robot's rolling angle reduce from±2° to±1° at the equilibrium point;The designed control algorithm can restore the robot from the starting angle of 18° to±1° at the equilibrium point,and the precession angle is also restored to the set boundary point around 8°;The robot's rolling angle can be restored to±1° at the equilibrium point when subjected to different impact or load loading;When the robot turns to the maximum value 45° during the steering movement,the robot's rolling angle can remain around 2°.To sum up,the designed control system can guarantee the stable performance of the robot.