Navigation and Control for Autonomous Spacecraft Proximity Operations with Uncooperative Satellites

-在轨服务的重要性**今天，卫星被用于许多不同的用途，例如遥感、全球导航和科学研究。它们还提供实时的全球通信，包括无线电、电话、互联网和电视。在诸如加拿大北部这样的偏远地区，固定电话和宽带互联网能力有限，几乎不存在，卫星电话和基于卫星的互联网连接是唯一的通信手段。最近的一项研究确定，未来10年将发射1200多颗卫星，这些卫星的制造和实施收入预计将达到1940亿美元。虽然大多数卫星不会出现重大问题，但统计数据预测，少数但数量可观的卫星将出现在轨异常或各种严重故障，给政府和私人组织造成数十亿美元的损失。许多研究表明，在轨道上使用服务航天器维修损坏或失效的卫星可以节省大量费用。**-技术挑战**在轨服务要求服务航天器执行具有挑战性的近距离操作，例如交会对接的目视检查和相对运动控制。为了使这些近距离操作可行，导航和控制能力必须比传统的单卫星任务得到改进，这意味着自主性的显著提高，以及高度精确的相对导航和轨迹控制。这些挑战在实际情况下更加复杂，因为由于机械或电气故障，或燃料耗尽，待维修的卫星可能会不合作，在某种意义上，它可能以未知的角速率旋转，没有通信能力，形状不确定，或具有未知的物理参数（质量和质量惯性矩）。此外，未建模的轨道扰动会干扰航天器的相对运动，从而影响航天器安全进行精确机动的能力。在此背景下，本研究的主要目标是开发智能导航和控制系统，使航天器能够与非合作卫星进行自主接近操作，从而推进在轨服务技术。具体而言，将提出以立体摄像机为依托的基于视觉的相对导航技术，并与创新的自适应控制理论相结合。这些系统将在现有的航天器近距离操作设施上进行实验验证，该设施由两个小型压缩空气推进航天器平台组成，可以在实验室环境中确定和控制它们的相对运动。**-结果和对加拿大的好处**该研究项目的结果将是一套指导方针和工具，使航天器设计师能够为近距离航天器开发最先进的导航和控制系统。拟议的计划将提高自主性，更安全的操作，更快的响应时间，更高的运动控制精度和增强在轨服务任务的鲁棒性。这反过来又将增加这些系统的能力，并使不合作卫星的在轨服务成为可能。鉴于加拿大对这种复杂空间业务的兴趣日益增加，这项研究将使加拿大空间组织在全球空间市场的这一利基领域处于这些技术的前沿。作为一个额外的好处，所开发的技术将应用于其他与航空航天有关的问题，包括与无人驾驶飞行器有关的问题。

- Importance of On-Orbit Servicing**Today, satellites are being used for many different applications, such as remote sensing, global navigation and scientific research. They also provide provide real-time, worldwide communication, including radio, telephone, internet, and television. In remote regions where landline telecommunication and broadband internet capabilities are limited to non-existent, such as Northern Canada, satellite phones and satellite-based internet connections are the only means of communication. A recent study determined that more than 1,200 satellites will be launched over the next 10 years, and revenues from the manufacture and implementation of these satellites is expected to reach $194 billion. While most will perform without major problems, statistics predict that a small but significant number will experience on-orbit anomalies or failures of various severity, resulting in losses of billions of dollars for governments and private organizations. As demonstrated by numerous studies, servicing damaged or failed satellites while in orbit with servicer spacecraft could achieve substantial savings.**- Technical Challenges**On-orbit servicing requires the servicer spacecraft to perform challenging proximity operations, such as visual inspection and relative motion control for rendezvous and docking. To make these proximity operations feasible, the navigation and control capabilities must be improved over traditional single-satellite missions, which means significantly increased autonomy, and highly accurate relative navigation and trajectory control. These challenges are further complicated in practical situations because, due to mechanical or electrical failures, or fuel depletion, the satellite to be serviced will likely be uncooperative, in the sense that it could be rotating at an unknown angular rate, have no communication capabilities, be of an uncertain shape, or have unknown physical parameters (mass and mass moments of inertia). Moreover, un-modeled orbital perturbations can disturb the relative motion of the spacecraft, thus impacting the capability to perform accurate maneuvers safely. **- Objectives and Proposal**In this context, the main objective of this research is to develop intelligent navigation and control systems enabling autonomous spacecraft proximity operations with uncooperative satellites, thereby advancing on-orbit servicing technologies. Specifically, vision-based relative navigation techniques relying on stereo cameras, to be merged with innovative adaptive control theories, will be proposed. These systems will be experimentally validated at the existing Spacecraft Proximity Operations facility, which consists of two small compressed air-propelled spacecraft platforms that can determine and control their relative motion in a laboratory environment.**- Outcome and Benefits to Canada **The outcome of this research program will be a set of guidelines and tools that enable spacecraft designers to develop the most advanced navigation and control systems for spacecraft in close proximity. The proposed program will lead to increased autonomy, safer operations, faster response times, higher motion control accuracy and enhanced robustness of on-orbit servicing missions. This, in turn, will increase the capabilities of these systems, and make on-orbit servicing of uncooperative satellites feasible. Given the increasing interests in such complex space operations in Canada, this research will place Canadian space organizations at the forefront of these technologies, in this niche of the global space market. As an added benefit, the techniques developed will have application to other aerospace-related problems, including those related to unmanned aerial vehicles.