Secure and Resilient Control of Constrained Cyber-Physical Systems Subject to Network Attacks

网络物理系统体现了基于网络的通信、软件、传感器和物理过程的紧密结合，有望在未来工程系统的设计和开发中发挥重要作用。旨在扰乱伊朗核浓缩厂运营的Stuxnet恶意软件，或影响乌克兰电网的Industroyer恶意软件，是影响CP的两个网络攻击例子。 研究现状表明，针对CP在攻击下的状态估计问题，已经提出了许多解决方案，但很少有人提出控制补救策略来保证受状态和输入约束的对象的安全。传统的容错和网络控制解决方案能够针对特定的物理故障和网络问题保证工厂的安全。然而，他们没有能力面对恶意的对手。另一方面，网络安全工具本身不足以应对CP，因为它们不知道网络攻击的物理影响。对于这样的推理，需要新的CPS安全和弹性方法来取代现有的方法。 该计划的长期目标是调查有希望的想法和解决方案，以便在通信通道上存在网络攻击的情况下，安全和弹性地控制受限的CP。从方法论的角度来看，将开发新的模型预测控制(MPC)方案来处理受约束的对象和攻击场景。短期内将面临不同的关键研究挑战：网络攻击的建模和表征，集合论估计工具的开发，以及能够协调检测和缓解攻击的统一控制架构的设计。 制定的控制方案将负责识别网络攻击并确保植物的弹性。只要涉及识别问题，首先将对攻击者可用的一组信息和资源进行表征，以识别攻击载体和破坏性资源。然后，开发基于水印思想的主动集论状态估计器模块，以防止不可检测的攻击。将通过求助于联网的强大的货币政策预测工具来获得物理对策。 该研究方案的主要创新方面是：联合检测和缓解网络攻击的能力，无论发生任何可接受的攻击都满足对象约束，以及由此产生的控制算法的实时可负担性。 拟议的研究结果将对能够提高未来工程系统安全性的新型控制体系结构的开发产生重大影响，这将不可避免地对加拿大经济产生广泛影响，并将改善我们的生活方式。

Cyber-physical systems (CPS) embody a tight integration between network-based communications, software, sensors and physical process and they are expected to play a significant role in the design and development of future engineering systems. The Stuxnet malware designed to disrupt the operations of an Iranian's nuclear enrichment plant or the Industroyer malware affecting the Ukrainian power grid are two examples of cyber-attacks affecting CPS. State of the art shows that many solutions have been presented for the problem of robust and resilient state estimation of CPS under attacks, but few control remediation strategies have been proposed to ensure the safety of plants subject to state and input constraints. Classical fault-tolerant and networked control solutions are capable of guaranteeing plant safety against specific physical faults and network issues. However, they are not capable of facing malicious adversary. On the other hand, cyber-security tools alone are not sufficient to deal with CPS because they are not aware of physical implications of cyber-attacks. For such reasoning, there is a need for new CPS security and resiliency methods overcoming existing approaches. The long-term objective of this program is the investigation of promising ideas and solutions for a secure and resilient control of constrained CPS in the presence of cyber-attacks on the communication channels. From a methodological perspective, novel model predictive control (MPC) schemes will be developed to deal with constrained plants and attack scenarios. Different key research challenges will be faced in the short-term: modeling and characterization of cyber-attacks, development of set-theoretic estimation tools, and design of unifying control architecture capable of detecting and mitigating attacks coordinately. The developed control schemes will be responsible for the identification of cyber-attacks and ensuring plant resiliency. As long as the problem of identification is concerned, first the set of information and resources available to the attackers will be characterized to identify attack vectors and disruptive resources. Then, active set-theoretic state estimator modules, based on watermarking ideas, will be developed to prevent undetectable attacks. Physical countermeasures will be obtained by resorting to networked robust MPC tools. The main innovative aspects of this research proposal are: capability to jointly detect and mitigate cyber-attacks, plant constraints fulfillment regardless of any admissible attack occurrence and real-time affordability of the resulting control algorithms. The outcome of the proposed research will have a significant impact on the development of novel control architectures capable of improving the security of future engineering systems which will unavoidably have a broad impact on Canadian economy and will enhance the way we will live.