动力翼伞纵向四自由度动力学仿真

在考虑载荷物和伞体相对运动的前提下,研究了动力翼伞纵向运动过程.将伞体和伞绳作为一个平面运动刚体,载荷物具有绕系挂点的摆动自由度,建立纵向四自由度动力学模型.求解翼伞从平飞至爬升状态推力阶跃操纵的动力学响应,由状态量的变化曲线得出动力操纵初期伞体失速倾覆的主要原因是迎角剧烈变化而超过失速边界.获得推力操纵值和推力增加速率所形成的操纵包线,当推力操纵幅度较小时,增加速率并无限制;当推力增加幅度较大时,增加速率的限制值随着增幅变大而减小.此外从能量角度计算了大动力快速操纵前后载荷物的机械能变化,并提出动力翼伞新的雀降操纵方式.计算表明该方法可以有效减少接地前后的能量,即可以减少接地后载荷物翻转对正面动力系统的冲击.

4-DOF longitudinal dynamic simulation of powered-parafoil

With the consideration of relative motion between payload and canopy, longitudinal dynamic of parafoil was simulated. Canopy and suspension line were regarded as a 3-DOF rigid body. Adding another degree of freedom of swing payload, a 4-DOF longitudinal dynamic model was proposed. Dynamic response was solved after step increasing of throttle which led to increasing of climbing angle. The main reason of canopy collapse that happens just after throttle up is the rapid changes of angle of attack which can be over the stall angle. Control envelope was calculated that is composed of throttle value and corresponding growing rate of throttle. Little change of power up has no limit on increasing rate, but large change does, and the limit increases with the increasing throttle value. In addition, mechanical energy change of payload before and after landing was calculated. Rapid power up control was proposed as a new flare landing method for powered-parafoil. The results of mechanical energy analysis method show that this new flare control can decrease mechanical energy at the moment of landing that means weaker shock to front power system.