基于结合力模型的自适应飞机防滑刹车控制

Adaptive control for aircraft anti-skid braking system based on friction force model

飞机在起飞和着陆过程中刹车系统工作的可靠性和效率的提高,对提升整个飞行周期的安全性有着重要的意义.针对不同的跑道状况(干、湿等)、跑道材质(沥青、软土)或温度等条件下,飞机轮胎与跑道之间的结合力会存在较大差异而直接影响刹车效果甚至有效性的问题,采用与速度相关的动态LuGre摩擦力模型表示结合力,将未知的跑道状态映射到结合力模型参数,通过对模型参数进行估计,达到对跑道状态进行识别的目的.首先建立飞机机体和机轮动力学模型,使用状态观测器对结合力模型中不可测量的内部摩擦状态变量进行估计,并由自适应律获得当前跑道状态对应的模型参数,而后在线求解结合力模型的伪稳态模型得到结合系数最大值及相应的滑移率,将此滑移率作为控制系统的跟踪目标,利用反馈线性化思想构造前馈控制器进行防滑刹车控制,最后通过仿真验证控制效果.

The improvements of aircraft braking system reliability and efficiency are important for the safety promotion of a whole flight circle. The aircraft tire/runway friction force varies significantly on different types of runways （ dry and wet, etc. ）, materials （ asphalt and soft ground, etc. ） and temperatures. This af- fects the braking control efficiency and even the effectiveness. The velocity correlative dynamic LuGre friction force model was introduced to describe the friction force, which could give a projective mapping from the phys- ical unknown runway state to mathematical model with parametric uncertainties, and then the runny state could be detected through parameter estimations. Firstly, the fuselage and aircraft wheel were modeled and the state observers were employed to estimate the unmeasurable internal friction states of the friction force model. The estimates were substituted into the parameter adaptive law to obtain the current runny state. Then the online calculation of pseudo-static friction force model was applied to obtain the maximum friction coefficient and its slip rate. This slip rate was set as the tracking target for the well-designed feed-forward controller based on the feedback linearization method. At last, the simulation results were shown to prove the control effects.