Design Of Two-wheeled Self-balance Vehicles

Two-wheeled self-balancing vehicle has become a hot spot in robot research area because they have prodigious potential and extensive prospect. Research achievements on two-wheeled self-balancing vehicles at home and abroad are reviewed and summarized, and then a prototype is designed and manufactured. There are two brushless DC hub motors equipped on both sides of the vehicle. The user, stand on the pedals of the vehicle, can steer the vehicle turning and going forward and backward by changing the gravity center of human body.The prototype consists of mechanical part and electric part. In order to modularized the electric part, the circuit is divided into main controller and motor driver, both of which are based on Cortex-M processors. The main controller measure the posture of the vehicle and calculate the required output torque of the BLDC motors on the basis of control algorithm, then the output instructions are sent to the motor drivers to drive the BLDC motors. The motor driver, verified by experiments waveforms, can achieve electronic commutation and closed-loop speed control. Proceed from safety, comfort and simple, driving and operation scheme of the vehicle is discussed. Design drawing and assembly drawing of the vehicle are given as well.Gyroscope and accelerometer are used to measure the vehicle’s posture. Gyroscope suffers drifting problem and accelerometer’s dynamic performance is poor. Therefore, none of their measuring results could be used all alone to restore the posture of the vehicle accurately. In order to meet the measuring requirement and compensate the shortage of gyroscope and accelerometer, both sensors are used to measure the posture of the vehicle and a filtering and data fusion algorithm is proposed. A testing platform is established and experiment result shows that the algorithm can accurately figure out the posture of the vehicle.The vehicle is mathematically modeled in allusion to the balancing and turning problem respectively. On the one hand, a self-adjusting parameter fuzzy control algorithm is proposed. The algorithm works out the common mode instruction of the two motors according to the pitch angle and balancing control is realized. On the other hand, a PID control algorithm is used to work out the difference mode instruction of the two motors according to the yaw angle and turning control is realized. The fuzzy controller lower the demand of the designer’s experience because it can adjust its parameters via comparing the difference between the response and given of the system and designer don’t need to select the parameters carefully. Simulation result in Simulink and experiment result in miniature prototype are given to verify the effectiveness of the fuzzy control algorithm.