For the easy cleaning problems of a certain type small UAV in the take-off and landing near the flight phase, a highly precise controller of the pitch angle to prevent table wiping the scheme of double ultrasonic. Mathematical model of the UAV flight near the ground plane, combined with the actual appearance characteristics, pitch angle stability control using the double loop, using classical control design of longitudinal control law of the machine, and the use of 2 ultrasonic altimeter to precisely control the attitude and path of small UAV. Analysis results show that:the control effect is good, can satisfy the longitudinal stability and control flight near and ensure the safety of the aircraft flight.%针对某小型无人机在起飞着陆的近地飞行阶段容易擦地的问题，提出一种用双超声波高度表精确控制俯仰角防止擦地的方案。建立该无人机近地飞行时的数学模型，结合飞机实际外形特点，采用双层回路进行俯仰角稳定控制，利用经典控制设计该机的纵向控制律，并运用2个超声波高度表来精确地控制小型无人机的姿态和轨迹。分析结果表明：该方案控制效果良好，可以满足近地飞行的纵向稳定和控制，保证飞机安全飞行。
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