| The study on electric anti-skid braking system adapts to the development of all-electric aircraft very well, and all-electric aircraft is aircraft's future. It will also be good to improving brake's performances and reliability, lighting weight, and so on. So the study is necessary.The composition and the principle of the electric anti-skid braking system on large civilian airplane are analyzed detailedly, base on which every composition's function is discussed, and model is set up. The actuator's composition is both analyzed and designed detailedly. Brushless DC Motor, which have a high power-weight ratio and high controllability, is chosen as the actuator's power. And it's composition and working principle are analyzed detailedly. The rotate speed adjustor with dual-closed feedback loop is designed as the control scheme.Nonlinearities effects in the electric braking system's working process are analyzed. The relation of friction coefficient and slip ratio is analyzed, so as the theory of the slip ratio's effect on friction coefficient. The relation of braking pressure and braking torque is also studied. It also studied the nonlinearities effects of torque ripple and speed detection device on the electric braking system's working process.As a new arithmetic, the pressure compensation control is designed as the control plan base on using slip ratio as the control variables. For the control system, the four actuators are divided into two groups, group A and group B. PID control is used in group A, and I/O control is used in group B. The pressure of group A is compensated immediately by group B at the pressure end directly, which is called the pressure compensation control. The pressure compensation control is used as the control algorithm. It is simulated in the Matlab and good result is presented and analyzed, which shows that the pressure compensation control is correct. |
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