NONLINEAR SIGHTLINE CONTROL

非线性视线控制

• 批准号: EP/D057558/1
• 负责人: David Anderson
• 金额: $ 15万
• 依托单位: University of Glasgow
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2006
• 资助国家: 英国
• 起止时间: 2006 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FD057558%2F1
• 关键词: NONLINEAR; SIGHTLINE; CONTROL

A sightline system encompasses all subsystems and algorithms necessary for accurate target tracking, pointing and stabilisation of a sensor line-of-sight. Each system integrates technologies obtained from several established research domains. The strategic intention of this research proposal is to develop sightline control as an independent, coherent research topic for the first time in the UK. The first step in achieving this objective is to apply rigorous research methodology to two of the most important sightline control problems / nonlinear nadir control and long-range imaging.The airline industry is severely hit by the economic after effects of terrorist actions (as seen post 9/11). There is therefore a need to adopt technologies that will safeguard aircraft security when operating in high-risk areas. One of the key military aircraft defence technologies identified by the U.S. Department of Homeland Security as a priority transition to the civil sector is the Directed Infra-Red Countermeasures (DIRCM) system (a technology in which the UK is a significant stakeholder). The purpose of such systems is to defend friendly aircraft against the threat posed by Man-Portable Air Defence Systems (MANPADS) / typically shoulder-launched Surface-to-Air Missiles (SAMs) / by tracking the incoming IR-guided missile and confusing the guidance mechanism through delivery of a jamming signal onto the missile seeker. However, for gimballed sightline systems, there exists a pointing angle that, were the target to pass through, infinite rate demands would be sent to one of the axes. This is known as the nadir and introduces significant additional tracking error, which is potentially disastrous for the aircraft. It is the intent of this project to investigate the applicability of several advanced control algorithms, using predictive methods, to minimising tracking error around the nadir and so improve the survivability of the aircraft.To obtain high-resolution images it is essential that sightline jitter be minimised, as jitter is often the dominant contributor to roll-off of the image modulation transfer function (MTF) at high spatial frequencies (blurs-out fine detail in the image). Jitter can be decomposed into two further sub-groups comprising sightline motion introduced by mechanical imperfections in the steering system (notably friction and vibration) and aberrations external to the system introduced by atmospheric turbulence. Control solutions for reducing mechanical jitter have been well researched, using, for example, classical control, friction estimation and robust methods, but very little nonlinear controller activity has been documented. The astronomical community has used adaptive optics for several years to correct for atmospheric distortions in the image by measuring the wavefront and using this information to control an extremely fast deformable mirror. However the complexity of such systems makes them unsuitable for deployment in an airborne environment. The alternative approach proposed here is to investigate the mapping between sightline jitter under nonlinear control and the shape of the MTF. The resulting controllers will, for the first time, be directly coupled to the quality of image obtained, which should see significant improvements in the attenuation of mechanical jitter while simultaneously taking the first steps in researching image-based atmospheric correction.

视线系统包括精确目标跟踪、指向和稳定传感器视线所需的所有子系统和算法。每个系统都集成了从几个已建立的研究领域获得的技术。这项研究计划的战略意图是在英国首次将视线控制发展为一个独立的、连贯的研究课题。实现这一目标的第一步是将严格的研究方法应用于两个最重要的视线控制问题/非线性最低点控制和远程成像。航空业受到恐怖行动的经济后果的严重打击（如9/11后所见）。因此，有必要采用在高风险地区作业时保障飞机安全的技术。美国国土安全部确定的优先向民用部门过渡的关键军用飞机防御技术之一是定向反导系统（DIRCM）系统（英国是该技术的重要利益相关者）。这种系统的目的是保护友机免受单兵携带防空系统（肩扛式导弹）（通常是肩扛式地对空导弹）的威胁，办法是跟踪来袭的红外制导导弹，并通过向导弹导引头发送干扰信号来扰乱制导机制。然而，对于万向节视线系统，存在一个指向角，如果目标穿过该指向角，无限速率需求将发送到其中一个轴。这被称为最低点，并引入了显着的额外跟踪误差，这对飞机来说可能是灾难性的。本项目的目的是研究几种先进的控制算法的适用性，使用预测方法，使最低点附近的跟踪误差最小化，从而提高飞机的生存能力。为了获得高分辨率图像，必须使视线抖动最小化，因为抖动通常是高空间频率下图像调制传递函数（MTF）滚降的主要因素（模糊图像中的精细细节）。抖动可以被分解成另外两个子组，包括由转向系统中的机械缺陷（特别是摩擦和振动）引入的视线运动和由大气湍流引入的系统外部的像差。减少机械抖动的控制解决方案已经得到了很好的研究，例如使用经典控制、摩擦估计和鲁棒方法，但很少有非线性控制器活动的记录。天文学界使用自适应光学已经有好几年了，通过测量波前来校正图像中的大气失真，并使用这些信息来控制一个非常快的变形镜。然而，这种系统的复杂性使得它们不适合在空中环境中部署。这里提出的替代方法是研究非线性控制下的视线抖动与MTF形状之间的映射。由此产生的控制器将第一次直接与所获得的图像质量相耦合，这将在机械抖动衰减方面取得显着改善，同时在研究基于图像的大气校正方面迈出第一步。

项目成果

Sightline Jitter Minimization and Shaping Using Nonlinear Friction Compensation

使用非线性摩擦补偿实现视线抖动最小化和整形

• DOI: 10.1080/15599610701548837
• 发表时间: 2007
• 期刊: International Journal of Optomechatronics
• 影响因子: 5.5
• 作者: Anderson D

Fast Model Predictive Control of the Nadir Singularity in Electro-Optic Systems

• DOI: 10.2514/1.30762
• 发表时间: 2009-04
• 期刊: Journal of Guidance Control and Dynamics
• 影响因子: 2.6
• 作者: David Anderson;Meghan McGookin;N. Brignall

Multirate and nonlinear controllers for low-cost laser tracking systems

用于低成本激光跟踪系统的多速率和非线性控制器

• 发表时间: 2007
• 作者: D Anderson

Application of MPC and sliding mode control to IFAC benchmark models

• 发表时间: 2008-09
• 作者: Meghan McGookin;David Anderson;E. McGookin