Control Research Of Air Based Anti-torqye Self-balance Unicycle Robot

Single wheel robot(SWR) is a kind of robot that imitates human being riding a unicycle, SWR is a typical under actuated, nonlinear, nonholononic, multi-coupling and static unbalance system,which has only one point contacting with the floor, compared with general wheeled robot. Its lateral and yaw direction are under actuated. The modeling and motion control of the self-balancing unicycle robot are important issues of both robotics and control science.This paper studies the anti-torque self-balance unicycle robot based on air flow. Unicycle robot based on inertia flywheel depends on the inertia wheel deceleration to provide restoring moment, cannot produce it in uniform phase. This paper uses the air flow based attitude controller to generates the anti-torque to control the lateral balancing of SWR. The restoring torque of this adjusting mechanism is positively related to the rotor speed, still can produce a torque in uniform phase. It overcomes the defect of traditional inertia flywheel. Aiming at this anti-torque SWR, the unicycle robot platform is designed, including the mechanical structure, the electronic system and the code. This paper establishes the dynamic model by the Lagrange method in the pitch and roll direction. The nonlinear PID method and Backstepping method are used to research the balance control of SWR. The key study and achievements of this paper are as follows:First: Design the platform of anti-torque SWR based on air flowThis paper designed the whole structure of anti-torque SWR. At the same time completed the electronic system including detecting system, control system and power system. The system uses ARM core board of STM32 series chips, responsible for the total balance control task. The attitude sensor is to test the real-time gesture. The actuator is a motor servo system, responsible for controlling the wheel to rotate to complete different control tasks. Designed a human-machine interface module, responsible for receiving real-time status information, and is responsible for the instruction issued.Second: The dynamic model of anti-torque SWR based on Lagrange method was established.First this paper established the mathematic model of the adjusting mechanism based on air flow, also the physical experiment which the restoring torque is positively related to the rotor speed is verified. Then the pitch direction and roll direction of the single wheel robot are decoupled. This paper used the Lagrange method to establish the dynamic model in pitch direction and roll direction and then verified the model. The model established provided a theoretical basis for the design and control of the anti-torque SWR.Third: Research on control method of anti-torque single wheel based on nonlinear PDTo the anti-torque balance of SWR control problem, this paper proposes a method based on the nonlinear PD control. The single wheel robot system is divided into the pitch direction control system and the roll direction control system. The pitch control system included motion control, pitch attitude control and motor servo control. The roll control included roll attitude control and motor servo control. The motor servo used two linear PID control to drive the wheel, and the attitude control used nonlinear PD to control the attitude balance of SWR. Through the comparison and analysis of nonlinear PD and linear PID, it is indicated that the dynamic performance of the nonlinear PD is better than that of the linear PID.Forth: Balance control based on the Backstepping control methodTo the anti-torque balance of SWR stability problem, this paper proposes a method based on the Backstepping control and design the control system. The stability of the control system was proved by Lyapunov. Build the corresponding Simulink model, conducted balance control test and the robustness tests.Simulink results demonstrate the effectiveness and the ability to effectively fight the interference of the control method.