The Control System Design Of Self-balance Two Wheels Electric Car

The self-balance two wheels electric car is a sort of inverted pendulum systemwhich is equipped with left and right wheels and can keep balance by itself. It is abranch of two while mobile robot. Sense it came out to be used as the manned transportmeans, it has got a lot of attentions widely in the market because of its advantageswhich include small footprint, flexible mobility, zero-radius turn and simple drivingmode and so on. At the same time, this kind of car is also an mechanical and electricalintegration system including drive module, power module, sensor module, controlmodule and mechanical body and so on, which widely refer to motor driver technology,power technology, sensor technology, signal process technology, control theory andmechanical design science and so on. In one hand, because of the complexity of thetechnology, there are only a few companies have the ability to research and design thiskind of car currently. So its technology is monopolized. On the other hand, thecomplexity of system increases the manufacturing and maintenance costs of the car, andreduces the reliability of its operation.The self-balance two wheels electric car is an electrical and mechanical integrationsystem that refers to motor driver technology, sensor technology, control theory andmechanical design science. This vehicle uses left and right motors to driver left andright wheels independently through retarders. It uses the combinational mode of thegyroscope and inclinometer to measure the attitude information of the vehicle body. Ituses the concept of dynamic balance to control balance of vehicle which is appliedwidely to aerospace, rock launch and other occasions. At the same time it will providemore convenience and reduced the difficulty for control program if mechanical designincluding the position of gravity center can be efficient. This paper just discusses theelectronic control rather than mechanical design. Accordingly it indicates that it’s thebasis for motor driver and sensor technology and the core for control theory. Efficientcontrol method must have the feature that is strong robustness, not sensitive toenvironment, can restore the balance quickly after disturbance, and have sample controlstructure.The key technology of self-balance two wheels electric car is the high-performancedynamic balance control. So this paper researches self-balance control method for thetarget that is designing a kind of self-balance control system and its key modules. This system should simplify the system structure on the basis of a good dynamic balanceperformance to reduce the production and maintenance costs of the car and improve thereliability of its operation. So this paper completed the following works specifically.First, design the hardware of the important module including attitude signaldetection module, the driver and buffer module of the motor driver main circuit.Second, design the attitude detection filter algorithm based on multi-sensor signalKalman filter to suppress the temperature drift and interference of sensors.Third, build the mathematical model of the self-balance two wheels electric car.This model built by this paper is different from the traditional model. It uses thearmature current of driver motor as control volume, rather than the armature voltage. Itcan describe the nature of self-balance control which is through controlling torquecurrent directly to control balance. So this paper refers to this model as direct torquemodel. Because establish the direct torque model, the speed-sensorless balance controlmode which could simplify the system structure can be constructed. This model is thebasis of the speed-sensorless balance controller design.Fourth, design the self-balance controller. This part is the core of this paper. Itdesigns speed-sensorless variable structure balance control method. To the traditionalbalance control methods of self-balance car, it needs all states including the speed of thecar to feedback to keep a good dynamic balance performance. So it must be installedwith the speed sensor. This will increase the system complexity. This paper designs akind of speed-sensorless variable structure balance controller, which doesn’t need speedsensor and can keep a good dynamic balance performance at the same time. It based ondirect torque model and equipped the sliding mode variable structure controller as thecore. Its control objective is making the balance state of the car body recover to theequilibrium position steadily and rapidly after disturbance, and ensuring systemdynamic stable. Its advantage is it doesn’t need speed sensor comparing to thetraditional control methods to reduce the system complexity and keep a good dynamicbalance performance. Through MATLAB simulation this paper verified the feasibilityand superiority of this method with the comparative simulation studies to the traditionalcontrol methods. Finally, this paper proposed the disadvantage of this control method,which is it can’t eliminate the instability risk brought by the integral effect of the speedby itself.According to this paper, finally produced a manned physical prototype machine ofself-balance two wheels electric car which don’t be installed with speed sensor and can runs successfully. It proves the feasibility of this design by practice.