Observer-Based CPS Control Under Cyber and Physical Attacks
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Solution Overview
Problem
Cyber Physical Systems (CPS) face challenges in secure control due to vulnerabilities from cyber and physical attacks, which can lead to system instability and undesired operations, especially when full state information is not available and attacks occur randomly with variable probabilities.
Innovation Solution
An observer-based controller is designed to detect attacks and adjust gains to secure physical and deception attack signals within specified thresholds, using a detector to inform the observer-based controller and estimate system states based on partial information, ensuring that physical attacks, denial of service, and deception attacks are mitigated.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional control methods are used in CPS, then the system can operate with simple control logic, but the system becomes vulnerable to cyber and physical attacks leading to instability
Solution Approach 1:
The control system dynamically adjusts the observer gain based on attack detection status. When attacks are detected, the gain is increased to enhance estimation accuracy and counteract attack effects. This dynamic adjustment allows the system to maintain stability under attacks without requiring permanently complex control structures.
Solution Approach 2:
An observer-based controller is introduced as an intermediary component between the system state and control input. This observer estimates the system state from available measurements and provides this estimation to the controller, enabling secure control without directly exposing the control system to attack vectors while maintaining reliability.
2Productivity
If full state information is available for control, then optimal control performance can be achieved, but the system requires complex sensing and information processing infrastructure
Solution Approach 1:
The observer acts as an intermediary that reconstructs full state information from partial measurements. Instead of requiring complex sensor arrays to directly measure all state variables, the observer uses available measurements combined with system dynamics models to estimate the complete state, maintaining control performance while reducing infrastructure complexity.
Solution Approach 2:
Physical measurement infrastructure is replaced with computational estimation. Rather than installing sensors to directly measure all state variables (mechanical/physical approach), the system uses computational observers to estimate states from available data, reducing hardware complexity while maintaining control performance.
3Reliability
If security protection measures are implemented in hardware and software, then the system can resist cyber attacks, but the system complexity and cost increase
Solution Approach 1:
The system implements feedback through attack detection mechanisms that monitor system behavior and provide information to the observer-based controller. When attacks are detected, the feedback loop adjusts the control strategy by modifying observer gains, providing security protection through control adaptation rather than requiring complex hardware/software security infrastructure.
Solution Approach 2:
The control system provides its own security protection through the observer-based controller that can detect and counteract attacks autonomously. Instead of requiring external security systems, the control system itself becomes security-aware and self-protecting by adjusting its behavior in response to detected attacks, reducing overall system complexity.
4Reliability
If the system operates without attack detection capabilities, then the control logic remains simple, but the system cannot respond to cyber and physical attacks
Solution Approach 1:
The observer gain is designed to be dynamic rather than fixed, capable of adjusting its characteristics based on attack detection. This dynamic property allows the system to maintain simple operation during normal conditions while automatically enhancing protection capabilities when attacks are detected, balancing complexity and reliability.
Data Source
AI summary
Methods, systems, and computer readable media to control a cyber physical system using an observer-based controller are described.