基于约束跟随理论的消防无人机水枪喷嘴跟踪控制

Tracking Control of Water-jet Nozzle for Firefighting UAV Based on Constraint Following Theory

利用无人机(Unmanned Aerial Vehicle,UAV)参与灭火是解决城市高层建筑消防问题的一种有效手段.针对无人机云台运动的控制问题,提出一种基于约束跟随理论的云台水枪喷嘴跟踪控制策略.根据高层建筑实际灭火需求,设计了云台水枪喷嘴两自由度驱动结构,采用Denavit-Hartenberg(D-H)方法对云台系统进行建模并由此完成云台运动学方程的建立.根据拉格朗日方程构建云台无约束动力学模型,把云台水枪喷嘴的期望轨迹作为约束,在不引入诸如拉格朗日乘数等任何变量或伪变量的情况下,基于Udwadia-Kalaba方程得到可以满足约束跟随需要的驱动转矩解析式,实现状态连续反馈控制,以达到水枪喷嘴轨迹跟踪的目的.为了减小跟踪误差,采用Baumgarte约束违约法进行稳定性处理,并在MATLAB/Simulink环境下对其轨迹跟踪控制进行仿真.搭建以数字信号处理器(Digital Signal Processor,DSP)为控制核心的实验平台进行轨迹跟踪控制实验.仿真和实验结果表明,基于约束跟随理论的轨迹跟踪控制算法能够有效地完成跟踪任务并实现对期望轨迹的高精度跟踪.

Using unmanned aerial vehicles(UAV) is an effective means to solve firefighting problems in urban high-rise buildings.This paper proposes a control strategy based on constraint following theory for the pan/tilt waterjet nozzle tracking to solve the problem of UAV pan/tilt movement control.First,according to the actual firefighting demand in high-rise buildings,the two-degree-of-freedom driving structure of the pan/tilt water-jet nozzle is designed.Second,Denavit-Hartenberg(D-H) method is used to model the pan/tilt system,and the pan/tilt kinematics equation is established.Then the dynamic model of pan/tilt without constraints is constructed according to the Lagrangian equation.The expected trajectory of the pan/tilt water-jet nozzle is regarded as the constraint.Without introducing any variables or pseudo-variables such as the Lagrange multiplier,the analytical formula of driving torque which can meet the requirement of constraints following is obtained based on the Udwadia-Kalaba equation,and continuous state feedback control is realized,which achieves the purpose of water-jet nozzle trajectory tracking.What's more,to reduce the tracking error,the Baumgarte method is used for stability processing,and the trajectory tracking control is simulated in Matlab/Simulink environment.Finally,an experiment platform with the digital signal processor(DSP) as a control core is built to conduct the trajectory tracking control.The results show that the control algorithm based on constraint following theory could effectively complete the tracking task and achieve high-precision tracking of the desired trajectory.