Abstract

Airships are inherently sensitive to random atmospheric disturbances that could potentially make their data gathering and observation missions a formidable task. In this context robust closed loop feedback controllers are important. The present study is therefore focused on optimal feedback controller design of an indigenous domestically designed airship (DA) for added robustness against atmospheric disturbances. While the general airship six degrees of freedom (6DoF) governing equations of motion are mathematically nonlinear, one often needs to resort to local linearization methods to benefit from proven linear closed loop controller (CLC) design approaches. In this sense an optimal linear quadratic regulator/tracker (LQR/LQT) seems to be a viable alternative for DA control purposes whose implementation relies on local linearization of the 6DoF nonlinear equations around the instantaneous airship trajectory. In order to demonstrate the capabilities of the proposed CLC design against external turbulences, a random wind profile over the DA hull is assumed and the airship behavior is analyzed in regulation as well as the tracking mode. The results show that the proposed CLC design complies with the all mission requirements and adequately reduces the impact of environmental random wind fluctuations. Given the small computational time required for control gain and command determination within the LQR/LQT algorithm against the DA mission flight time, the proposed CLC can be utilized online as a feedback control strategy while the airship is performing any physical atmospheric experiment.

摘要

飞艇天生对随机的大气扰动很敏感，这可能使它们的数据收集和观测任务成为一项艰巨的任务。在这种情况下，稳健的闭环反馈控制器很重要。因此，本研究的重点是本土设计的飞艇 (DA) 的最佳反馈控制器设计，以增加对大气干扰的鲁棒性。虽然一般飞艇六自由度 (6DoF) 控制运动方程在数学上是非线性的，但通常需要借助局部线性化方法才能从经过验证的线性闭环控制器 (CLC) 设计方法中受益。从这个意义上说，最优线性二次调节器/跟踪器 (LQR/LQT) 似乎是用于 DA 控制目的的可行替代方案，其实现依赖于围绕瞬时飞艇轨迹的 6DoF 非线性方程的局部线性化。为了展示所提议的 CLC 设计对外部湍流的能力，假设 DA 船体上的随机风廓线，并在调节和跟踪模式下分析飞艇行为。结果表明，所提出的 CLC 设计符合所有任务要求，并充分降低了环境随机风波动的影响。鉴于 LQR/LQT 算法相对于 DA 任务飞行时间的控制增益和命令确定所需的少量计算时间，